Air Quality Criteria for Particulate Matter. INSTITUTION National Air Pollution Control Administration (DHEW), Washington, D.C

DOCUMENT RESUME

ED 070 647 SE 015. 367 TITLE Air Quality Criteria for Particulate Matter. INSTITUTION National Air Pollution control Administration (DHEW), Washington, D.C. REPORT NO NAPCA-AP-49 PUB DATE Jan 69 NOTE 218p.

EDRS PRICE MF-$0.65 HC-$9.87 DESCRIPTORS *Air Pollution Control; *Environmental Criteria; Environmental Influences; *Literature Reviews; *Matter; Pollution; Quality Control; Standards ABSTRACT To assist states in developing air quality standards, this book offers a review of literature related to atmospheric particulates and the development of criteria for air quality. It not only summarizes the current scientific knowledge of particulate air pollution, but points up the major deficiencies in that knowledge and the need for further research. Focused upon is total particulate matter of the kind' normally measured by high--Volume and paper-tape sampling methods and by dustfall collection. Further, it considers the effects of particulate matter conjunction with some gaseous materials where important synergistic effects are observed. Methods of measuring the effects of particulate matter on meteorological conditions, atmospheric visibility, materials, and vegetation are documented, as well as the resulting economic loss. Public awareness of air pollution and the role of particulate matter in the odor problem are assessed. There is a chapter on the respiratory system, discussing particulate deposition therein and removal therefrom, necessary to understanding the final chapters which survey toxicological effects of particulate'matter and the epidemiological data for man and animals. A glossary of terms, lists of symbols, abbreviations, and conversion factors for various units of measurement, author index* and subject index are provided. (BL)

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AIR QUALITY CRITERIA FOR PARTICULATE MATTER

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FOR

PARTICULATE MATTER

U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE Public Health Service Consumer Protection and Environmental Health Service National Air Pollution Control Administration Washington, D.C. January 1901 National Air Pollution Control Administration Publication No. AP-49

a Preface

Air quality criteria tell us what science has broad atmospheric areas of the Nation in thus far been able to measure of the obvious which climate, meteorology, and topography, as well as the insidious effects of air pollu- all of which influence the capacity of air to tion on man and his environment. Such cri- dilute and disperse pollution, are generally teria provide the most realistic basis thatwe homogeneous. presently have for determining to what point Further, the Act requires the Secretary to the levels of pollution must be reduced if we define those geographical regions in the are to protect the public health and welfare. country where air pollution is a problem The criteria that we can issue at the pres- whether interstate or intrastate. These air ent time do not tell us all that we would like quality control regions will 1>e designated on to know. If all of man's previous experience the basis of meteorological, social, andpo- in evaluating environmental hazards pro- litical factors which suggest that agroup of vides us with a guide, it is likely that im- communities should be treated as a unit for proved knowledge will show that thereare setting limitations on concentrations of at- identifiable health and welfare hazards as- mospheric pollutants. Concurrently, the Sec- sociated with air pollution levels that were. retary is required to issue air quality criteria previously thought to be innocuous. As our for those pollutants he believes maybe harm- scientific knowledge grows, air quality cri- ful to health or welfare, and to publishre- teria will have to be reviewed and, in all lated information on the techniques which probability, revised. But the Congress has can be' employed to control the sources of made it clear that we are expected, without those pollutants. delay, to make the most effectiveuse of the Once these steps have been taken for any knowledge we now have. region, and for any pollutant or combination The Air Quality Act of 1967 requires that of pollutants, then the State or States respon- the Secretary of Health, Education, and Wel- sible for the designated region are on notice fare "...from time to time, but as soon as to develop ambient air quality standards ap- practicable, develop and issue to the States plicable to the region for the pollutants in- such criteria of air quality as in his judgment volved, and to develop plans of action for may be requisite for the protection of the implementing the standards. public health and welfare.. . . Such criteria The Department of Health, Education, and shall... reflect the latest scientific knowl- Welfare will review, evaluate and approve edge useful in indicating the kind and extent these standards and plans, and once they are of all identifiable effects on health and wel- approved, the States will be expected to take fare which may be expected from the pres- action to control pollution sources in the man- ence of an air pollution agent. ..." ner outlined in their plans. Under the Air Quality Act, the issuance of At the direction of the Secretary, the Na- air quality criteria is a vital step in a pro- tional Air Pollution Control Administration gram designer to assist the States in taking hasestablished appropriate programs to responsible technological, soicial; and politi- carry out the several Federal responsibilities cal action to protect the public from the ad- specified% the legislation. verse effects of air pollution. Air Quality Criteria for Particulate Mat-. Briefly, the Act calls for the Secretary of ter is the culmination of intensive and dedi- Health, Education, and Welfare to define the cated effort on the part of many personsso

iii many, in fact, that it is not practical to name mospheric pollution by particulate matter. all of them. These efforts, without which this document In accordance with the Air Quality Act, a could not have been completed successfully, National Air Quality Criteria Advisory Com- are acknowledged individually on the follow- mittee was established, having a member- ing pages. ship broadly representative of industry, uni- As also required by the Air Quality Act of versities, conservation interests, and all lev- 1967, appropriate Federal departments and els of government. The committee, whose agencies, also listed on the following pages, members are listed following this discussion, were consulted prior to issuing this criteria provided invaluable advice on policies and document. A Federal consultation committee, procedures under which to issue criteria, and comprising members designated by the heads provide major assistance in drafting this of seventeen departments and agencies, re- document. To facilitate the committee's work, viewed the document, and met with staff per- subcommittees were formed to provide inten- sonnel of the National Air Pollution Control sive efforts relating to specific pollutants Administration to discuss their comments. initially for particulate matter and for sul- This Administration is pleased to acknowl- fur oxides. edge the efforts of each of the persons specif- ti With the help of the Subcommittee on Par- ically named, as well as the many not named ticulate Matter, expert consultants were re- who contributed to the publication of this tained to draft portions of this document, volume. In the last analysis, however, the Na- with other segments being drafted by staff tional Air .Pollution Control Administration members of the National Air Pollution Con- is responsible for its content. trol Administration. After the initial drafting, there followed a sequence of review and revision by the subcommittee, and by the full r. committee, as well as by individual reviewers especially selected for their competence JOHN T. MIDDLETON, and expertise in the many fields of science Commissioner, National Air Pollution and technology related to the problems of at- Control Administration

iv NATIONAL AIR QUALITY CRITERIA ADVISORYCOMMITTEE

Chairman DR. JOHN T. MIDDLETON, Commissioner National Air Pollution Control Administration

Dr. Herman R. Amberg. Dr. Neil V. Hakala Manager, Manufacturing Services Dept. President Central Research Division Esso Research & Engineering Co. Crown Zellerbach Corp. Linden, N.J. Camas, Wash. Dr. Ian T. Higgins Dr. Nyle C. Brady Professor, School ofPublic.Health Director, Agricultural Experiment The University of Michigan Station Ann Arbor, Mich. Cornell University Mr. Donald A. Jensen Ithaca, N.Y. Executive Engineer Dr. Seymour Calvert Ford Motor Co. Director, Statewide Air Pollution Dearborn, Mich. Research Center Dr. Herbert E. Klarman University of California, Riverside Professor of Public Health Administration Riverside, Calif. and Political Economy Dr. Adrian Ramond Chamberlain School of Hygiene and Public Health Vice President Johns Hopkins University Colorado State University Baltimore, Md. Fort Collins, Colo. Dr. Leonard T. Kurland Professor of Epidemiology *Dr. Raymond F. Dasmann Mayo Graduate School of Medicine Senior Ecologist Head, .Medical Statistics Conservation Foundation Epidemiology and Population Genetics Washington, D.C. Section, Mayo Clinic Mr. James R. Garvey Rochester, Minn. President and Director Dr. Frederick Sargent II Bituminous Coal Research, Inc. Dean, College of Environmental Monroeville, Pa. Sciences Dr. David M. Gates University of Wisconsin Director Green Bay, Wis. Missouri Botanical Gardens Mr. William J. Stanley St. Louis, Mo. Director, Jhicago Department of Air Pollution Control * Resigned, October 14, 1968. Chicago, Ill. CONTRIBUTORS AND REVIEWERS Dr. Donald F. Adams Dr. Ellis F. Darley Head, Air Pollution Research Division Plant Pathologist College of Engineering Statewide Air Pollution Research Center Washington State University University of California at Riverside Pullman, Wash. Riverside, Calif. Dr. Mary 0. Amdur Dr. Arthur DuBois Associate Professor of Toxicology Department of Physiology Department of Physiology Graduate School of Medicine School of Public Health University of Pennsylvania Harvard University Philadelphia, Pennsylvania Boston, Mass. Dr. James G. Edinger Professor of Meteorology Dr. Rodney R. Beard University of California Executive Head, Department Los Angeles, Calif. of Preventive Medicine Stanford University Medical School Dr. Lars Friberg Palo Alto,. Calif. Chief, Department of Hygiene Karolinska Institute of Hygiene Dr. Francis E. Blacet Stockholm, Sweden Emeritus Professor of Chemistry University of California at Los Angeles Dr. Sheldon K. Friedlander Los Angeles, Calif. Professor of Chemical Engineering and Environmental Health Engineering Dr. L. J. Brasser California Institute of Technology Head, Atmospheric Pollution Division Pasadena, Calif. Research Institute for Dr. John R. Goldsmith Public Health Engineering Chief, Environmental Hazards Delft, The Netherlands Evaluation Unit Department of Public Health Dr. Leslie A. Chambers State of California Professor and Chairman Berkeley, Calif. Department of Environmental Health School of Public Health Dr. Leonard Greenburg University of Texas Professor of Preventive and Houston, Tex. Environmental Medicine Albert Einstein College of Medicine Dr. Robert Charlson New York, N.Y. Research Associate Professor of D. Alexander Goetz Atmospheric Chemistry Senior r3tr.rf Consultant Department of Civil Engineering National Center for Atmospheric University of Washington Research Seattle, Wash. Altadena, Calif. Dr. Morton Corn Dr. Paul Gross Associate Professor, Department of Director, Research Laboratory Occupational Health Industrial Hygiene Foundation of Graduate School of Public Health America, Inc. University of Pittsburgh Mellon Institute Pittsburgh, Pa. Pittsburgh, Pa. vi Dr. Harry Heimann Dr. James P. Lodge Research Associate, Department of Program Scientist, National Center Physiology for Atmospheric Research School of Public Health Boulder, Colo. Harvard University Boston, Mass. Dr. Thomas C. Lloyd, Jr. Dr. Walter W. Holland Associate Professor, Department of Professor, Department of Clinical Physiology Epidemiology and Social Medicine School of Medicine St. Thomas' Hospital Medical School Case Western Reserve University University of London Cleveland, Ohio London, England Mr. John A. Maga Mr. John H. Jacobs Executive Officer Principal Research Physicist Air Resourc,:s Board, State of Bell & Howell Research Center California (Chicago, Ill.) Sacramento, Calif. Pasadena, Calif. Dr. P. E. Joosting Dr. Roy McCauldin Medical Service Professor, Department of Environmental Research Institute for Engineering Public Health Engineering College of Engineering Delft, The Netherlands University of Florida Gainesville, Fla. Mr. Elmer R. Kaiser Senior Research Scientist Dr. Herbert C. McKee School of Engineering and Science Assistant Director, Department of New York University Chemistry and Chemical Engineering New York, N. Y. Southwest Research Institute Dr. Herbert Landesman Houston, Tex. Consulting Chemist Pasadena, Calif. Dr. Paul E. Morrow Professor of Radiatibii Biology and Dr. Phillip A. Leighton Biophysics Emeritus Professor of Chemistry School of Medicine and Dentistry Stanford University University of Rochester Palo Alto, Calif. Rochester, N. Y. Dr. Mark H. Lepper Professor of Preventive Medicine Dr. Edward D. Pa lmes University of Illinois College Professor of Environmental Medicine of Medicine Institute of Environmental Medicine Chicago, Ill. New York University Medical Center New York, N. Y. Mr. Robert H. Linnell Staff Associate, Departmental Science Dr. James N. Pi, Jr. Development Section Professor of Chiimmistry National Science Foundation University of California at Riverside Washington, D.C. Riverside, Calif. Mr. Benjamin Linsky Dr. Walter A. Quebedeaux, Jr. Professor, Department of Civil Engineering Director, Harris County Air West Virginia University and Water Pollution Control Division Morgantown, W. Va. Houston, Tex. Dr. Donald D. Reid Dr. Moyer D. Thomas Professor of Epidemiology and Director Editor. Inter-Society Committee Manual of of Department Methods for Ambient Air Sampling and Department of Medical Statistics and Analysis Epidemiology Riverside, Calif. London School of Hygiene and Tropical Medicine Dr. Amos Turk London, England Professor, Chemistry Department The City College of the City University Dr. Elmer Robinson of New York Chairman, Environmental Research New York, N. Y. Department Mr. Hans K. Ury Stanford Research Institute Special Consultant Menlo Park, Calif. Environmental Hazards Evaluation Unit California State Department of Public Health Dr. Stanley N. Rokaw Berkeley, Calif. Chief, Pulmonary Research Section Mr. Ralph C. Wands Rancho Lcs Amigos Hospital Director, Advisory Centeron Toxicology Los Angeles, Calif. National Research Council Washington, D.C. Dr. August T. Rossano Richard P. Wayne Professor, Air Resources Program Oxford University Department of Civil Engineering. London, England University of Washington Visiting Professor in Photochemistry Seattle, Wash. University of California at Riverside 'Riverside, Calif. Mr. Jean J. Schueneman Chief, Division of Air Quality Control Dr. Phillip W. West Maryland State Department of Health Professor of Chemistry Baltimore, Md. College of Chemistry and Physics Louisiana State University Baton Rouge, La. Dr. Wayne T. Sproul' Consultant in Physics Dr. Warren Winkelstein, Jr. Pasadena, Calif. Professor and Head, Division of Epidemiology Dr. Gordon H. Strom School of Public Health Department of Aeronautical University of California Engineering Berkeley, Calif. College of Engineering Dr. Harold Wolozin New York University Professor and Chairman New York, N. Y. Economics Department University of Massachusetts Dr. 0. Clifton Taylor Boston, Mass. Associate Director Mr. John E. Yocom Statewide Air Pollution Research Center Senior Research Engineer University of California at Riverside Travelers Research Center, Inc. Riverside, Calif. Hartford, Conn.

viii FEDERAL AGENCY LIAISON REPRESENTATIVES Department of Agriculture Department of the Treasury Kenneth E. Grant Gerard M. Brannon Associate Administrator Director Soil Conservation Service Office of Tax Antslysis Federal Power Commission Department of Commerce F. Stewart Brown Paul T. O'Day Chief Staff Assistant to the Secretary Bureau of Power Department of Defense General Services Administration Thomas E. Crocker Colonel Alvin F. Meyer, Jr. Chairman Director Repair and Improvement Division Environmental Pollution Control Committee Public Buildings Service Department of Housing and Urban National Aeronautics and Space Development Administration Charles M. Haar Major General R. H. Curtin, USAF (Ret.) Assistant Secretary for Metropolitan Director of Facilities Development NationcZ Science Foundation Dr. Eugene W. Bier ly Department of the Interior Program Director for Meteorology Harry Perry Division of Environmental Sciences Mineral Resources Research Advisor Post Office Department Department of Justice Louis B. Feldman Walter Kiechel, Jr. Chief Assistant Chief Transportation Equipment Branch General Litigation Section Bureau of Research and Engineering Land and Natural Resources Division Tennessee Valley Authority Dr. F. E. Gartrell Department of Labor Assistant Director of Health Dr. Leonard R. Linsenmayer Deputy Director Atomic Energy Commission Bureau of Labor Standards Dr. Martin B. Biles Director Department of Transportation Division of Operational Safety William H. Close Veterans Administration Assistant Director for Environmental Gerald M. Hollander Research Director of Architecture and Engineering Office of Noise Abatement Office of Construction AIR QUALITY CRITERIA FOR PARTICULATE MATTER

TABLE OF CONTENTS Chapter Page

Preface iii Introduction xiii 1Atmospheric Particles:Definitions, Physical Properties, Sources Concentrations 1 2Effects of Atmospheric Particulate Matter on Solar Radiation and and Climate Near the Ground 33 3Effects of Atmospheric Particulate Matter on Visibility 47 4Effects of Atmospheric Particulate Matter on Materials 63 5Economic Effects of Atmospheric Particulate Matter 77 6Effects of Atmospheric Particulate Matter on Vegetation 87 7Social Awareness of Particulate Pollution 97 8 Odors Associated with Atmospheric Particulate Matter 103 9 The Respiratory System: Deposition, Retention, and Clearance of Particulate Matter 109 10Toxicological Studies of Atmospheric Particulate Matter 127 11Epidemiological Appraisal of Atmospheric Particulate Matter 145 12 Summary and Conclusions 179

Appendices ASymbols 192 BAbbreviations 193 CConversion Factors 194 DGlossary 195 Author Index 204 Subject Index 208 Acknowledgements 211

xi INTRODUCTION

Pursuant to authority delegated to the and are used as one of several factors in de- Commissioner of the National Air Pollution signing legally enforceable pollutant emission Control Administration, Air Quality Criteria standards. for Particulate Matter is issued in accord- The particulate matter commonly found ance with Section 107b1 of the Clean Air Act dispersed in the atmosphere is composed of (42 U.S.C. 1857c-2b1). a large variety ofsubstances. Some of Air quality criteria are an expression of theseflourides, beryllium, lead, and asbes- the scientific knowledge of the relationship tos, for exampleare known to be directly between various concentrations of pollutants oxic, although not necessarily at levels rou- in the air and their adverse effects on man tinely found in the atmosphere today. There and his environment. They are issued to as- may very well be others whose toxic effects sist the States in developing air quality have not yet been recognized. To evaluate standards. Air quality criteria are descrip- fully the effects on health and welfare of the tive; that is, they describe the effects th.lt presence of each of these substances in the have been observed to occur when the am- air requires that they be given individual at- bient air level of a poliutant has reached or tention, attention as classes of similar sub- exceeded specific figures for a specific time stances, or that they be considered in con- period. In developing criteria, many factors junction with other substances where syner- have to be considered. The chemical and gistic effects may occur. Such evaluations physical characteristics of the pollutants and will be made at a later time in separate docu- the techniques available for measuring these ments. characteristics must be considered, along This document focuses on total particulate with exposure time, relative humidity, and matter of the kind normally measured by other conditions of the environment. The cri- high-volume sampling methods, by paper- teria must consider the contribution of all tape sampling methods, and by dustfall col- such variables to the effects of air pollution lection. Further, this document considers the on human health, agriculture, materials, vis- effects of particulate matter in conjunction ibility, and climate. Further, the individual with some gaseous materials, such as sulfur characteristics of the receptor must be taken dioxide, where important synergistic effects into account. Table A, which appears at the are observed. (Atmospheric sulfur oxides end of this introduction, is a listing of the are treated in detail in a companion criteria major factors that need to be considered in document: Air Quality Criteria for Sulfur developing criteria.' Oxides.) No attempt is made in this docu- Air quality standards are prescriptive. ment to set up dose-response relationships They prescribe pollutant exposures which a for specific particulate pollutants. Also, the political jurisdiction determines should not large and diverse contributions of agricul- be exceeded in a specified geographic area, tural and forest management operations to air pollution, such as insecticide spraying and slash burning, and the ingestion hazard to Calvert, S. Statement for air quality criteria hearings held by the Subcommittee on Air and Water animals and man of toxic particulate matter Pollution of the U.S. Senate Committee on Public deposited on plant materials, are treated only Works. July 30, 1968. for a few selected examples; details are be- 12 i:1 yond the scope of this document. Table A.FACTORS TO BE CONSIDERED IN Methods of measuring the effects of partic- DEVELOPING AIR QUALITY CRITERIA ulate matter on meteorological conditions? at-_ Properties of Pollution: mospheric visibility, and materials aritilocu- Concentration mented, as well as is the resulting economic Chemical composition Mineralogical structure loss. The effects of particulate matter are Adsorbed gases further considered as they relate to vegeta- Coexisting pollutants tion damage. :Public awareness of air pollu- Physical state of pollutant tion and the role of particulate matter in the Solid odor problem are assessed. There is, a chap- Liquid ter on the respiratory system,' Gaseous Rate of transfer to receptor domain late deposition therein and removal there- Measurement Methods: from, necessary to understanding of the final Hi-Vol sampler chapters which survey toxicological effects Spot-tape sampler of particulate matter and the epidemiological Duet fall bucket (rate of deposition) data for man and animals. Condensation nuclei counter Impinger (liquid filled) In general, the terminology employed fol- Cascade impactor lows usage recommended in the publications Electrostatic precipitator style guiie of the American Chemical So- Light scattering meter Chemical analysis ciety. A glossary of terms, listsof symbols and Gas analysis (non-adsorbing) abbreviations, list-Of -conversion factors for Adsorbed gas analysis various units of measurement, author index, Light scattering or attenuation and subject index are provided. . (Ringleman or visibility observation) Colored suspension The literature has been generally reviewed Nucleation of precipitation on a worldwide basis through March 1968. Stabilization of fog The results and conclusions of foreign in- Odor vestigations are evaluated for their possible Taste Exposure Parameters: application to the air pollution problem in Duration the United States. This document is not in- Concomitant conditions, such as tended as a complete, detailed literature re- Temperature view, and it does not cite every published Pressure article related to atmospheric particulates. Humidity Characteristics of Receptor: However, the literature has been reviewed Physical characteristics' thoroughly for information related to the Individual susceptibility development of criteria, and the document State of health not only summarizes the current scientific Rate and site of transfer to receptor knowledge of particulate air pollution, but Responses: Effects on health(diagnosable effects, latent points up the major deficiencies in that effects, and effects predisposing the organism knowledge and the need for furt er research. to disease) : Technological and economic aspects of air Human health Animal health pollution control are considered in compan- Plant. health ion volumes to criteria documents. The best Effects on human comfort methods available for controlling the sources Soiling of particulate air pollution, as well as the Other objectionable surface deposition costs of applying these methods, are de- Corrosion of materials Deterioration of materials scribed in: Control Techniques for Particu- Effects on atmospheric properties late Air Pollutants. Effects on radiation and temperature

13 xiv Chapter 1

ATMOSPHERIC PARTICLES: DEFINITIONS, PHYSICAL PROPERTIES, SOURCES, AND CONCENTRATIONS

14 Table of Contents Page

A. INTRODUCTION 5 B. PROPERTIES OF ATMOSPHERIC PARTICULATEMATTER Lr 8 1. Surface Properties 8 2. Motion 9 3. Optical Properties 9 C. CHEMICAL REACTIONS OF ATMOSPHERICPARTICULATE MATTER 10 D. SOURCES OF ATMOSPHERIC PARTICULATE MATTER 10 E. ATMOSPHERIC PARTICULATE MATTER IN URBANAREAS 11 1. Suspended Particulate Matter 11 2. Dustfall 16 F. SAMPLING AND ANALYSIS OF ATMOSPHERIC PARTICULATE MATT ER 17 1. Particles Larger than 10p 17 2. Particles 0.1p to 10p 19 a. Tape Samplers for Suspended Particulate Matter 20 b. High-Volume Samplers for Suspended ParticulateMatter 22 3. Particles Smaller than 0.4 23 G. SIZE, CHEMICAL COMPOSITION, AND SOURCE STRENGTHS OF 'PARTICULATE MATTER FROM SELECTED EMISSION SOURCES 23 1. Open Hearth Furnaces 23 a. Chemical Composition 23 b. Particle Size 23 2. Incineration 24 a. Chemical Composition 24 b. Particle Size 25 3. Sulfuric Acid Manufacture: Chamber Process 25 a. Chemical Composition 25 b. Particle Size 25 4. Sulfuric Acid Manufacture: Contact Process 25 a. Chemical Composition 25 b. Particle Size _4-- 25 5. Cement Plants 25 a. Chemical Composition 25 b. Particle Size 26 6. Motor Vehicles 26 a. Chemical Composition 26 b. Particle Size 26 7. Fuel Oil Combustion 26 a. Chemical Composition 26 b. Particle Size 27 8. Combustion of Coal 27 a. Chemical Composition 27 b. Particle Size 27 2 1 Page

H. SUMMARY 27 I. REFERENCES 29

List of Figures Figure 1-1Sizes of Atmospheric Particulate Matter 6 1-2Setting Velocities in Still Air at 0°C and 760 mm Pressure for Par- ticles Having a Density of 1 g/cm3 as a Function of Particle Diameter 7 1-3Log-Normal Distribution of Particles Showing Various Average 7 Diameters 1-4Particle Size Distribution of Figure 1-3, Plotted Logarithmically 7 1-5Cumulative Logprobability Curire for the Distribution of Figure1-4. 8 1-6Horizontal Elutriator Cut -off Characteristics 17 1-7Dustfall Data for Six Cities 18

List of Tables Table 1-1Emission Inventory of Particulate Material, Tons Per Year 12 1-2Suspended Particle Concentrations (Geometric Mean of Center City Station) in Urban Areas, 1961 to 1965 13 1-3Distribution of Selected Cities by Population Class and Particle Concentration, 1957 to 11967 15 1-4Distribution of Selected Nonurban Monitoring Sites by Category of Urban Proximity, 1957 to 1967 15 1-5Arithmetic Mean and Maximum Urban Particulate Concentrations in the United States, Biweekly Samplings, 1960 to 1965 16 1-6Emission Factors for Selected Categories of Uncontrolled Sources of Particulates 24

16 81+ Chapter 1 ATMOSPHERIC PARTICLES: DEFINITIONS, PHYSICAL PROPERTIES, SOURCES, AND CONCENTRATIONS

A.INTRODUCTION ambiguous. For example, "size" has been taken to mean both diameter and radius. Atmospheric particles are chemically a Again some workers interpret size to mean most diverse class of substances; they do, the physical or geometrical size, while others however, have a number of physical proper- mean some equivalent size based, for ex- ties in common, and for this reason are gen- ample, on optical laws relating the size of erally classed in a single category, sometimes aerosol particles to the measured scattering referred to as aerosols. of a light beam. In this document, "size" ordi- Some workers restrict concept of par- narily refers to particle diameter or Stokes' ticulate matter to the solid phase; this dis- diameter as defined below. tinction is, however, difficult to make in prac- Particles larger than about a micron in di- tice and is probably not proper. Others refer ameter settle in still air at velocities approxi- to airborne particles as nuclei because of mated by Stokes' Law: their role in the nucleation of condensation, especially of liquid or solid water. In this gd2 (plp2) document, the term "particle" is used to mean 18 n any dispersed matter, solid or liquid in which where the individual aggregates are larger than vis velocity in cm/sec (settling single small molecules (about 0.0002p1 in di- :velocity or terminal velocity), ameter), but smaller than about 5001L. [One gis the acceleration of gravity in micron (p.) is one-thousandth of a millimeter cm /sect, or one-millionth of a meter.] Particles in this dis particle diameter in cm, size range have a life-time in the suspended P1and are the densities of the state varying from a few seconds to several particle and of air respectively months. in g/cm2, and Many disciplines are involved in the study n is viscosity of air in poise. of particles, and each appears to have devised The expression is precisely true only for its own system of nomenclature to differenti- spheres. An upper limit to its applicability is ate classes of particles with respect to size, set by the fact that, when a certain settling physical state, origin, etc. Periodic, but rath- velocity is reached, the particle generates a er unsuccessful attempts have been made to significant "wake". A lower limit is reached resolve the confusion.1 The present document when the particles become small enough, will discuss the several classes of particles by around 1p, that air resistance is no longer specifying the size or size interval in microns continuous but is rather the result of individ- (p) and, where appropriate, the physical ual collisions with air molecules. Under these state. Figure 1-1 provides a graphic scheme conditions the particles "slip" between mole- for relating meteorologic nomenclature for cOes and the Stokes' equation underesti- aerosols to the particle sizes. Nonspherical mates their falling velocity. Correction fac- particles may be idealized as spheres which tors exist to allow for this behavior, but thy would have the same settling rate, but even need not be given here for the qualitative dis- so, size designations have frequently been cussion which follows. The approximate set-

5 1'7(I K.

Aitken NOMENCLATURE Large Giant Particles Panicles Pa ticles

i . ATOMS, MOLECULES (Not Particles) Small AIR ii Larpslons w 0 ELECTRICITY za I-11- . Ions < Z x ,x ATMOSPHERIC tu OPTICS Particles t'i 0° CO a. 2 CLOUD Active PHYSICS Condensation Nuclei AIR CHEMISTRY minas*

- , Main Aerosol

Suspended ROUTINE AIR Particulate Metter POLLUTION >MEASUREMENTS Dunhill

10-4 10.3 10.2 10 "1 100 101 102 DIAMETER,,LL FIGURE1-1. Sizes of Atmospheric Particulate Matter' (The figure shows theranges of particle size (diameter) of various types of particulate matter which are found in the earth'satmosphere.)

tling velocities in still air at 0°C and 760 mm than 1. A few quantitative examplescan be k pressure for particles having a density of 1 given:' a1psphere of lead with a density of g /cm' are: approximately 11 has a reduced sedimenta- 0.14t,8 x 10-5 cm/sec; 1p, 4 X 10-3 cm/sec; tion diameter of 3.4p; a bubble of air in water 10p, 0.3 cm/sec; 100p., 25 cm/sec; and with an outer diameter of 1p anda water 1,000p, 390 cm/sec. (See Figure 1-2.) film thickness of 0.1, and consequentlya den- In the case of a nonspherical particle, sub- sity of approximately 0.5 g/cm3hasa reduced stitution of v, g,pi, p2, and a in equation sedimentation diameter of 0.7p- Nonspherical (1-1), Stokes Law, leads to a fictitous diam- particles can also be assigneda "diameter" eter, d, which is known as the Stokes or aer- based on their settling rate. A rectangular G-IyAamic diameter. Unless otherwise stated, plate of density 1 g /cm', and dtmenzions 5 x the word "diameter," as applied to particles 5x 0.5p., has a reduced sedimentation diam- suspended in air or gas, ordinarily means eter near 2p. Stokes diameter. Some of the smallest particles may beno If the density,p, of the particles is not more than statistical aggregations of gas known, it may arbitrarily be assigneda value molecules which act as a particle at one in- of 1 g/c3 ; in this case d is no longer the stant and cease to exist at the next. Solid "Stokes diameter" but rather the "reduced particles and liquid droplets may be formed sedimentation diameter"that is, the diam- in the atmosphere by condensation ofa va- eter of a spherical particle of unit) density por. So:id particles produced by abrasion or having the same terminal fall velocity-4h still grinding are not sphercial and are called air as the particles in question. dust. The geometrical diameter of a particle will This discussion of size classes must not be smaller than the reduced sedimentation di- obscure the fact that there is a continuous ameter if the particle has a density greatier spectrum of sizes among the particles in the 6 18- 103 0.8 COUNT MODE (0.61911) 0.7 102 COUNT MEDIAN MOM ARBITRARILY SET ATONE 0.6

10 1

COUNT MEAN (1.27211) O 100 cc a. 0LL DIAMETER OF AVERAGE 104 MASS (2.056p) AREA MEDIAN (2.61411) U O 0. AREA MEAN (3.324p) 10-2 MASS MEDIAN (4.2261) i5 0.1 MASS MEAN 3 (5.37411) 104 0 2 3 4 5

PARTICLE DIAMETER, ti 1

FIGURE 1-3.Log-normal Distribution of Particles 10-5 showing Various Average Diameters.' (The graph is drawn from probability theory, assuming a count 104 100 101 102 103 104 DIAMETER OF PARTICLE, MICRONS median diameter of lib and shows the numerical values relative to that diameter of several other FIGURE 1-2.Settling Velocities in Still Air at 0° C weighted average diameters discussed in the text.) and 760 mm Pressure for Particles Having a Den- sity of 1g /cm' as a Function of Particle Diameter. (This graph shows that, for spherical particles of unit density suspended in air near sea level, Stokes law applies over a considerable range of particle z.0. sizes, where the line is straight, but that correction is required at The extremes where the line begins N to curve.) a

1 atmosphere acid.ecorresponding continuous

7 that a straight line is obtained if the distribu- the quantity (e.g., mass) lies on either side of tion is truly log normal; the best line is fitted a median diameter, while a mean value refers either by eye or mathematically. Such a plot to the diameter of particles possessing a spe- is shown in Figure 1-5, and the experimental cific weighted average of a quantity. A more points give an idea of the extent to which the extensive mathematical treatment of these size distribution of a typical industrial dust quantities is given in books by Cad le 5 and by approximates to log-normal. Drinker and Hatch.6 A distribution curve based on an exact mathematical function can be specified in B.PROPERTIES OF ATMOSPHERIC terms of two parameters. In the case of the PARTICULATE MATTER log-normal distribution, two frequently used Since particulate matter may consist of defining parameters are (1) the most proba- such a wide variety of substances, .a discus- ble size, which in this distribution is identical sion of chemical properties of the class can- with the geometric mean, M,, and (2) the not be specific. Some selected chemical prop- geometric standard deviation, ag. It can be erties of important individual species will be shown that the 50 percent point of the cumu- discussed later in connection with analytical lative graph (Figure 1-5) corresponds to methods. Biological properties are most con- veniently grouped in terms of the effects produced. Many physical properties are equally diverse. Diamond particles are harder than gypsum particles of the same size, while hardness in this sense has no meaning for liquids. Shapes are just as varied, although there is a general tendency towards spherical shape with decreasing size as surface energy (which is a minimum for spheres) predominates over crystal energy. Only three general classes of physical properties can reasonably be said to apply to all particulate matter. 0.1 1 5 10 50 These properties all involve the interface CUMULATIVE, % between the particle and its1 surroundings, and they are (1) surface FIGURE1-5. Cumulative Log-probability Curve for properties,(2) mo- the Distribution of Figure 1-4. (In a cumulative tions, and (3) optical properties. A discu'.- plot, the experimental points fall on a straight line sion of the properties of aerosols has been when the size distribution is log-normal. The 50% given by Corn,2 and it should be used to ex- point corresponds to the geometric mean, M, tend the remarks offered below. (about 111, in this case) and the ratio of the 84.1% point to this (about 22/11 or 2, in this case) is 1.Surface Properties the geometric standard deviation, a,. In practice, the experimental points usually lie near a straight Surface properties include sorption, nu- line, as shown.) cleation, adhesion, etc. Sorptive behavior can best be understood by considering the impact Ms, while the ratio of the 84.1 percent point of individual molecules on the particle sur- to the 50 percent point is fry face. If this impact is perfectly elastic and Several averages of particle size may be rebound is truly instantaneous, nothing hap- employed and these may be based on aver- pens. If, however, rebound is delayed or the ages of numbers, areas, masses, etc. Some of velocity of rebound is smaller than that of the most important averages are indicated in impact, then there will be a local accumula- Figure 1-3, and the numerical values cal- tion of the gas on or near the particle surface. culated for the distribution are given relative If the delay is great, a substantial fraction of to a count (number) median diameter of 11,.4 the surface may be covereda phenomenon The terms used are self-descriptive; half of known as adsorption. If the delay is caused 8 specifically by a chemical interaction between des are always present in the atmosphere, the surface and the gas, the process is known nucleation on them is of widespread occur- as chemisorption. Absorption refers to the rence. situation in which the gas is dissovled into The last of the surface properties of conse- fi the particle. quence is adhesion. All available evidence A vapor (i.e., a gas below its critical tem- suggests that solid particles with diameters perature), present in amounts comparable to less than lft (and liquid particles regardless its equilibrium vapor pressure, may lead to of size) always adhere when they collide a deepened sorbed layer, which then takes on with each other or with a larger surface. the character of a layer of true liquid or solid. Other factors being equal, reentrainment or If the vapor is supersaturated, a droplet or rebound becomes increasingly probable with crystal may grow by further condensation on increasing particle size.Alternatively, the the sorbed layer. The net result is nucleation, adhesive property can be considered in terms a phenomenon which deserves more consid- of the surface energy of small particles or eration. A pure vapor, free of particles, must in terms of the more complex shear forces be highly supersaturated before a condensed acting to dislodge the larger particles. phase will form from it, because an energy barrier separates the molecular from the par- 2.Motion ticulate state. Two like molecules of gas will not general- The second major class of properties com- ly stick together, and an aggregate of three mon to all particles, regardless of composi- molecules is still less likely to retain its iden- tion, is their mode of motion. Particles with tity for any length of time. A wall aggregate sizes less than 0.1tt undergo large random of molecules is therefore unstable. On the (Brownian) motions caused by collision with other hand, if a particle is split in two, energy individual molecules. Particles larger than is required to create the new surfaces, since ltt have significant settling velocities, and the combined surface area of the two frag- their motions can vary significantly from the ments is greater than that of the original motion of the air in vich they are borne. particle (surface energy increases with a de- For particles between 0.1/4 and ltt, settling crease in size). At some point, these two velocities in still air, though finite, are small trends of decreasing stability meet at a maxi- compared with air motions. Despite fairly mum which corresponds to a certain particle high concentratiors, coagulation is some- size. If a molecular aggregate can reach this what slower as compared with particles size, then the addition of a single molecule smaller than0.1p because of decreased puts it over the energy barrier and it will be- Brownian motion. Nevertheless, the oper- come more stable by collecting still more mol- ation of this mechanism, together with the ecules. Conversely, the loss of a single mole- processes which generate larger particles and cule from a nucleus 0 critical size can de- which remove particles from the air,causes stroy its stability with the probable result the whole population of particulate matter in that it will return to the molecular or gaseous the air to tend towards a constant size dis- state. tribution. The important point is that the critical Although actual settling times in the "at- particle generally contains some tens of mole- mosphere tend to differ from those computed cules which must all come together at once. from Stokes Law, because turbulence tends Unless the vapor concentration is high, this to offset gravitationalfall, the particles is an improbable event; for some substances, larger than kt or 10tt are removed to a large homogeneous nucleation may even require extent by gravity and other inertial proc- supersaturations of many hundredfold. }low:,esses. ever, a complete sorbed layer on a particle 3.Optical Properties surface behaves like a drop of the same diam- The final class of physical properties to eter as the particle, and the energy barrier to be discussed is that of the behavior ofpar- producing a droplet is avoided. Since parti- ticles towards light. This behavior is clearly 21 9 1

of importance in effects on visibility, and it tides collected on filters may, however, react is through their optical effects that particles and subsequent analysis can be very mislead- are usually perceived in the atmosphere. ing if this fact is not taken into account. Once again, particles in the size range 0.1p One of the particle-gas systems, the reac- to 1L exhibit properties showing a transition tion between sulfuric acid mist and ammonia between two extreme cases. gas, was investigated by Robbins and Cadle.8 Particles below 0.1p are sufficiently small At high humidities the reaction rate was lim- compared to the wavelength of light to obey ited by diffusion of ammonia to the mist approximately the same laws of light scatter- droplets.At low humidities the droplets ing as molecules do. This so-called Rayleigh were viscous enough to result in diffusion of scattering varies as the sixth power of the the reaction product away from the surface particle diameter and is fairly inconsequen- of the drops being the rate-determining step. tial in its effects on visibility. On the other This work shows the effect of accumulation hand, particles very much larger than 1p of reaction products, and attempts to explain are so much larger than the wavelength of the role of humidity in a gas-particle reac- visible light that they obey the same laws tion. as macroscopic objects, intercepting or scat- Goetz and Pueschelreported a study tering light roughly in proportion to their which fully reveals the complexity of even cross-sectional area. Particles in the inter- a simplified model of the photochemical air mediate size range obey complex scattering pollution found in Los Angeles. The one laws set forth by Mie; r these laws are be- clear relationship is that the amount of re- yond the scope of the present discussion. Be- action product deposited on nuclei supplied cause the particle dimensions are of the same from the gas phase is proportional to the order of magnitude as the wavelength of visi- surface area of the nuclei. The humidity ef- ble radiation, interference phenomena play fectis complex and depends upon the a complicating role, and a given scattering amounts and the order bt.asidition of the behavior may correspond to several particle other substances present. The obvious re- sizes.Unfortunately, this is precisely the actants (olefins, nitrogen dioxide, and sul- size range which is most effective is light fur dioxide) differ in action as well. Amounts scattering and thus most needful of study. of sulfur dioxide of the order of 2 ppm A more complete discussion of optical effects depressaerosolformation, while larger is given in Chapter 3. amounts (15-16 ppm) increase it. Nitrogen dioxide is more effective if mixed with nuclei C. CHEMICAL REACTIONS OF before mixing with the olefin. ATMOSPHERIC PARTICULATE Interactions between sulfur dioxide and MATTER metal oxide aerosols have recently been stud- In view of the diverse chemical composi- ied by Smith et al." at ambient conditions of tions of particles, it is not possible to make temperature and humidity. In measurements general statements about the chemical reac- that included an adsorption isotherm for sul- tions of particulate atmospheric pollutants, fur dioxide on dispersed particles, preferen- and the following discussion refers to some tial chemisorption on iron oxide and alumi- specific reaction systems that have been num oxide aerosols was observed at low studied. Both particle-gas and particle-par- sulfur dioxide concentrations (up to 2 ppm) ticle reactions can occur, but the latter class followed by multilayered physical adsorption has been studied to an even lesser extent at higher concentrations. than the former. Such particle-particle reactions shout,d certainly occur in the size D. SOURCES OF ATMOSPHERICr..4 range below 0.1,L where collision between PARTICULATE MATTER particles is frequent,but, in particles large In a broad sense, particles in the abno,q- enough to be readily studied,' collisionsare phere are produced by two mechanisms: relatively infrequent in the atmosphere be- those in the size range below 1ig arise prin- cause of low concentrations. Samples of par- cipally by condensation, while larger par- 10 tides result from comminution, although salt will be found in particles of this size. there is considerable overlap. For example, The finer process dusts (ash, etc.) also fall Preining et al." showed the presence of into this category.In short, atmospheric many particles smaller than 1p in the spray particles in the 1-p to 10-p range tend to have from a nebulizer, while the formation of very a composition characteristic of local sources small drops during the rupture of bubbles and soil. has been demonstrated." Dry grinding proc- As mentioned before, it is difficult to form esses are rarely efficient in producing par- small particles by size reduction. The class ticle sizes below a few microns because of of particles between 0.1p and 1p compared the rapid increase in energy necessary to with the larger particles therefore tends to produce the additional surface. contain increasing amounts of condensation Combustion is complex in that it may pro- products. Products of combustion begin to duce four distinct types of particles. These predominate together with photochemical may arise in the following ways: aerosols. Particles below 0.1p have not been 1. The heat may vaporize material which charaderized chemically but the increase subsequently condenses to yield parti- over the natural level, characteristic of cities, cles in the size range between 0.1p and seems to be entirely the result of combustion. 1p, Table 111 shows typical particulate emis- 2. the energy available produces particles sion source data.Section G-1 gives some of very small size (below 0.1p) ; these typical analytical data on particulate matter particles may be of short life as a result by industry source. of their being unstable molecular clusters, E. ATMOSPHERIC PARTICULATE MITER IN URBAN AREAS 3. mechanical processes may reduce either fuel or ash to particle sizes larger than . 1.Suspended Particulate Matter 1p and may entrain it, The fraction of aerosol mass in the par- 4. if the fuel is itself an aerosol during ticles below 0.1p is small and concentrations combustion, a very fine ash may escape are normally reported in number per unit directly, and volume. Even the cleanest air rarely contains 5. partial combustion of fossil fuels may fewer than some hundreds of particles per result in soot formation. cubic centimeter, and the particle count in Particles larger than 10p frequently re- very polluted urban air " may reach 103/cma. sult from mechanical processes such as wind The bulk of current data on suspended erosion, grinding, spraying, etc., although particles generally does not discriminate on raindrops, snowflakes, hailstones, or sleet the basis of size. Most data come from the are obviously not produced in this way. National Air Surveillance Network (former- The sources of dust are usually apparent. ly the National Air Sampling Network.l 13 For example, a dustfall sample nearly always Blifford 20 has applied factorial analysis to contains particles of local soil. Another large these data to show relationships among in- fraction will be materials dropped on the dividual pollutantspecies.Average sus- ground and pulverized by vehicles, pedestri- pended particle mass concentrations range ans or wind action. Although actual soot from about -10 pg/m3 in remote nonurban flocs are increasingly absent as better home areas to about 60 pg/m3 in near urban loca- heating is used, there may be partially burnt tions. In urban areas, averages range from trash from inefficient incinerators. Finally, 60 pg/m3 to 220 pg/m3, depending on the size the process dust characteristic of local in- of the city and its industrial activity. In dustry will be present. In urban locations heavily polluted areas, values of up to 2000 particles between 1p. and 10µ generally re- items have been recorded. flect industrial and combustion processes Table 1-2 lists the average suspended par- with some local soil also present. In mari- ticle concentrations for a number of stand- time locations, the bulk of the airborne sea ard metropolitan statistical areas through- . silo,. 11 Table 1-1.-EMISSION INVENTORY OF PARTICULATE MATERIAL, TONSPER YEAR.

Metropolitan Area New York- Source Class New Jersey 1$ Washington 14 St. Louis 15 Los Angeles IS 1966 1966-66 1963 1966 Tons Percent Tons Percent Tons Percent Tons Percent

Fire! combustion 184,410 68.1 19,280 56.4 86,800 68.9 8,680 18.8 Power generation 40,042 17.8 9,912 28.622,400 16.2 4,826 10.6 Coal 81,722 18.7 22,400 16.2 Anthracite 47 Bituminous 81,676 13.7 9,890 28.4 Fuel Oil 7,698 3.8 22 0.1 Distillate 19 0.1 Residual 7,698 3.8 Natural Gas 727 68 Industrial 88,599 14.5 851 1.089,000 26.6 780 1.6 Coal 28,442 10.5 186 0.4 87,990 25.8 Anthracite 8,022 8.6 Bituminous 16,420 6.7 186 0.4 Fuel Oil 9,669 4.1 182 0.5 688 0.5 Distillate 1,479 0.6 28 0.1 Residual 8,090 8.6 169 0.5 Natural *Gas 688 84 0.1 428 0.8 Domestic 41,078 17.8 8,166 9.1 19,900 18.5 2,425 6.6 Coal 17,767 7.7 786 2.1 18,873 12.8 Anthracite_ 16,561 7.2 686 2.0 Bituminous 1,206 0.6 60 0.1 Fuel Oil 21,680 9.8 1,889 6.8 671 0.6 Distillate 16,826 6.6 1,164 3.3 Residual 6,264 2.7. 686 2.0 Natural Gas 1,726 0.7 692 1.7 864. 0.2 Commercial and Government 19,696 8.6 5,851 16.8 5,600 8.7Included with Coal 8,189 8.6 8,891 11.2 6,460 3.7 domestic Anthracite 4,482 1.9 163 0.4 Bituminous 8,707 1.6 3,788 10.7 Fuel Oil 10,894 4.7 1,814 6.2 84 Distillate 8,281 1.4 661 1.9 Residual 7,618 3.8 1,168 8.8 Natural Gas 668 146 0.4 27 Refuse disposal 41,784 18.0 8,165 28.4 15,800 10.7 865 0.8 Incinerator 1,700 1.2 865 0.8 Open burning 14,100 9.6 Transportation 86,245 (16.2 6,246 18.0 7,100 4.8 21,586 47.0 Motor Vehicles 88,761 14.6 6,678 16.3. 4,700 8.2 17,155 87.5 Gasoline 22,680 9.8 4,081 11.6 4,100 2.8 16,426 86.9 Diesel 11,181 4.8 1,64'i 4.7 600 0.4 780 1.6 Aircraft 410 1.2 211 0.1. 4,016 8.8 Shipping 1,484 0.6 670 0.6 865 b 0.8 Railroads 167 0.5 1,500 1.0 Industrial Process 19,914 8.6 1,110 8.2 87,600 26.4 18,866 88.6 Aaphalt Batching 198 0.1 365 0.8 Asphalt Roofing NA 1,095 2.4 'ent Plants 8,600 2.4No plants ChMical Plants NA 2,920 6.8 Coffee Processing 88 Not reported Coke Plant Not reported Not reported 78 No plants Glass and Frit. Not reported Not reported'' NA 780 1.6 Grain Industry 6,696 4.5 Not reported flee footnotes at end of table. 12 Table 1-1 (continued).-EMISSION INVENTORY OF PARTICULATEMATERIAL, TONS PER YEAR.

Metropolitan Area New York- Source Class New Jersey 11 Washington u St. Louis 15 Los Angeles 16 1966 1965-66 1963 1966 Tons Percent Tons Percent Tons Percent Tons Percent

Metals 12,433 8.3 2,920 6.4 Ferrous 12,392 8.3 1,460 3.2 Nonferrous 41 1,460 8.2 Solvent Uses NA 6,470 11.9 Sulfuric Acid Mfg 192 0.1Not reported Superphosphate Mfg 43 0.2No plants Other 14,063 9'. 6 366 0.8

Total 231,308 100.0.34,790 100.1147,400 100.0 44,346 100.0

Both aircraft and shipping. Includes chemical plant emissions of solvents. Both shipping and railroads. NA Not available.

Table 1-2.-SUSPENDED PARTICLE CONCENTRATIONS (GEOMETRIC MEAN.OF CENTER CITY STA- TION) IN URBAN AREAS, 1961 TO 1965.

Total Benzene-soluble Standard metropolitan statistical area suspended particles organic particles pg/m, Rank pg/m Rank

Chattanooga 180 1 14.6 2 Chicago-Gary-Hammond-East Chicago 177 2 9.6 19.6 Philadelphia 170 3 10.7 12.6 St. Louis 168 4 12.8 4 Canton 166 6 12.7 6 Pittsburgh 163 6 10.7 12.6 Indianapolis 168 7 12.6 6 Wilmington 154 8 10.2 16 Louisville 162 9 9.6.. 18 Youngstown 148 10 10.5 14 Denver 147 11 11.7 8.6 Los Angeles-Long Beach 146.6 12 16.6 1 Detroit 148 13 8.4 28 Baltimore 141 . 14.6 11.0 10 '' Birmingham 141 14.6 10.9 11 Kansas City 140 16.6 8.9 28 York 140 16.5 8.1 84 New York-Jersey City-Newark-Passaic-Patterson-Clifton 186 18 10.1 16 Akron 184 20 8.8 30.6 Boston 184 20 11.7 8.6 Cleveland 184 20 .8.8 80.6 Cincinnati 188 22.6 8.8 26 Milwaukee 188 22.6 7.4 42 Grand Rapids 181 24 7.2 44.6 Nashville 128 26 11.9 7 Syracuse 127 26 9.3 28 Buffalo. 126 27.6 6.0 66 Reading 126 27.6 8.8 26 Dayton 128 29 7.6 40.6 Allentown-Bethlehem-Easton 120.6 80 6.8 60 Columbus 118 81.6 7.6 40.6 Memphis 118 31.6 7.6 89

13 -.1.111-

Table 1-2 (continued). - SUSPENDED. PARTICLE CONCENTRATIONS (GEOMETRIC MEAN OF CENTER CITY STATION) IN URBAN AREAS, 1961 TO 1965.

Total Benzene-soluble Standard metropolitan statistical area suspended particles organic particles Pg/M 1 Rank 14g/m1 Rank

Portland (Oreg.) 108 34 9.5 19.5 Providence 108 34 17.7 38 Lancaster 108 34 6.8 50 San Jose 105 36.5 14.0 3 Toledo 105 36.5 5.6 58 Hartford 104 38.5 7.1 46 Washington 104 38.5 9.4 21 Rochester 103 40 6.1 55 Utica-Rome 102 41 7.0 47 Houston 101 42 6.8 50 Dallas 99 43 8.8 25 Atlanta 98 44.5 7.8 36 5 Richmond 98 44.5 8.3 30 5 New Haven 97 46 7.3 43 Wichita 96 47 5.2 60 Bridgeport 93 50 7.2 - 44 5 Flint 93 50 5.3 59 Fort Worth 93 50 7.8 36.5 New Orleans 93 50 9.7 17 Worcester 93 50 8.2 33 Albany-Schenectady-Troy 91.5 53 6.6 52 Minneapolis-St. Paul 90 54 6.5 53 San Diego 8E" 55 8.5 27 San Francisco-Oaldand EO 56 8.0 35 Seattle 77 57 8.3 30.5 Springfield-Holyoke 70 58 7.0 47.5 Greensboro-High Point 60 59 6.3 54 Miami 58 60 5.7 57

out the United States. For the most part, concentrationfor theperiod 1958-1967, measurements were taken at a single sam- while Table 1-4 shows the frequency distri- pling station in the downtown area of the bution of particle concentration in nonurban city. areas for the same period. Based on ten years of sampling at ap- Particle concentrations in air have both proximately 370 sites, the highest seasonal diurnal and annual (seasonal) cycles which average will exceed the annual mean by 15 for most cities are generally predictable in to 20 percent.Seasonal averages for the shape. A city with cold winters will experi- high 2 percent of the sites exceeded the an- ence a seasonal maximum in midwinter as nual mean by 50 percent and the lowest 2 a result of increased fuel use for space heat- percent exceeded the annual mean by about ing. A daily maximum in the morning, 5 percent.Individual 24-hour maximum probably between 6 and 8 o'clock, usually re- sample concentrations vary widely from the lates to a combination of meteorological fac- annual mean, and on the average this vari- tors and an increase in the strength of ation is from 280 to 300 percent. Variations sources of particulates, including the auto- as high as 700 percent of the annual mean mobile traffic. are found for the high two percent of the A reflection of the effect of the strength of samples. Sunday and holiday data are us- various sources can also be seen in the pre- ually 15 to 20 percent below weekday con- viously mentioned lower weekend and holi- centrations. Table 1-3 shows the relation day versus weekday concentrations.

of population class of urban areas to particle . In cities where photochemical pollution

14: Vi7 Table 1-3. DISTRIBUTION OF SELECTED CITIES BY POPULATION CLASS AND PARTICLE CONCENTRATION, 1957 TO 1967. (Avg. particle concentration pg/ms)

40 60 80 100 120 140160 180 Total Total Population class <40to to to to to to to to>200 cities cities 59 79 99 119 189 159 179 199 in tablein U.S.A.

>8 million 1 1 2 2 1-8 million 2 1 3 3 0.7-1 million 1 2 4 400-700,000 4 5 6 1 1 1 18 19 100-400,000 8 7 80 24 17 12 3 2 1 99 100 50-100,000 2 20 28 16 12 6 5 1 3 93 180 26-50,000 5 24 12 12 10 2 1 2 8 71 10-25,000 7 18 19 9 5 2 8 1 64 5,458 <10,000 1 5 7 15 11 2 1 2 44

Total urban 1 22 77 108 79 52 81 16 8 7 401

Incorporated and unincorporated areas with population over 2,500.

Table 1-4.DISTRIBUTION OF SELECTED NON- to samples taken in the center-city commer- URBAN MONITORING SITES BY CATEGORY cial district. This portion of the community OF URBAN PROXIMITY, 1957 TO 1967.n will generally not show annual average concentrations as high as those found in various Average particle industrial areas; however, they are among Category concentrations, agfins Total the higher area concentrations in a com- <2020-8940-5960-79 munity. Annual concentrations in nearby suburban residential areas generally will be Near urban 1 8 1 5 about one-half of that found in center city. Intermediate b 5 6 11 Particulateairpollutionisnot only Remote 4 5 9 source- and location-dependent but is also Total a function of meteorological factors causing nonurban 4 11 9 1 25 a variation in the natural ventilation of a community. Air pollution episodes are char- Near urbanalthough located in unsettled areas, acterized by minimum natural ventilation, pollutant levels at these stations clearly indicate in- and particulate concentrations at such times fluence from nearby urban areas. All of these stations are located near the northeast coast "population cor- may rise dramatically as indicated by the ridor." following examples: during the November- b Intermediatedistant from large urban centers, December, 1962,episode in the Eastern some saricultural activity, pollutant levels suggest that United States, particulate concentrations in some influence from human activity is possible. Remoteminimum of human activity, negligible several communities rose to two-to-three agriculture, sites are frequently in state or national times normal; " during the Thanksgiving forest preserve or park areas. 1966 episode, again in the Eastern United States, particulate concentrations increased predominates, the maximum in concentra- by about a factor of two over mean autumn tion of particles in the range from 0.1p to 1i4 levels. In fact, maximum citywide average may come around noon, after the sun has concentrations in Philadelphia, Worcester, had an opportunity to cause photochemical and Boston exceeded maximum concentra- reaction. Under these conditions, the highest tions recorded for an autumn period since concentration of particles below 0.1p will 1961 at the National Air Surveillance Net-' come earlier, and there may be no clear trend work (NASN) stations." for larger particles. Table 1-5 gives concentrations of certain The above concentrations generally relate specific contaminants found in total sus-

15 Table. 1-5. ARITHMETIC MEAN AND MAXIMUM URBAN PARTICULATE CONCENTRATIONSIN THE UNITED STATES, BIWEEKLYY SAMPLINGS,. 1960 TO 1965.21

Concentrations pg/ms Pollutant ;. Number of stations Arith. average Maximum

Suspended particulates 291105 1254 Fractions: Benzene-soluble organics 218 6.8 (b) Nitrates 96 2.6 39.7 Sulfates 96 10.6 101.2 Ammonium 56 1.3 75.5 Antimony_ 35 0.001 0.160 Arsenic 133 0.02 (b) Beryllium 100<0.0005 0.010 Bismuth 35<0.0005 0.064 Cadmium 35 0.002 0.420 Chromium 103 0.015 0.330 Cobalt 35<0.0005 0.060 Copper 103 0.09 10.00 Iron 104 1.58 22.00 Lead 104 0.79 8.60 Manganese 108 0.10 9.98 Molybdenum 35<0.005 0.78 Nickel 103 0.034 0.460 Tin 85 0.02 0.50 Titanium 104 0.04 1.10 Vanadium 99 0.050 2.200 Zinc 99 0.67 58.00 Gross beta radioactivity 323 (0.8 pci/ms) (12.4 pCi /m')

Arithmetic averages are presented to permit comparable expression of averages derived from quarterlycom- posite samples; as such they are not directly comparable to geometric means calculated for previous years' data. The geometric mean for all urban stations during 1964-65 was 90 pg/ms, for the nonurban stations, 28 pg/ms. b No individual sample analyses performed. pended particulate matter. Certain sub-frac- erable and the current trend is clearly in tional contaminants found in total particu- their favor. Typical values for cities are lates may be related to community param- 0.35 to 3.5 mg /cm= -month (10 to 100 tons/ eters; for example, average ambient vana- mile'- month), While values approaching 70 dium concentrations correlate well with the mg /cm -month (2000 tons/mile2-month) have kind of residual oil used, iron and manganese been measured nearespeciallyoffensive correlate and are attributed to their joint sources. emission from ferromanganese blast fur-. naces, and annual gasoline sales correspond A search for scientific interpretations or with the average lead fraction of suspended correlations of dustfall data has been unsuc- particulates.Similarly,sulfates correlate cessful. There is no question that, within a with particulates in those communities which given city, dustfall tends to increase with derive large amounts of energy from the the intensity of human activity.Further- higher sulfurous fuels." more, dusifall measurements are certainly valuable in obtaining evidence against major 2.Dustfall sources of dust. However, trying to extract Dustfall is the usual index of particles in detailed information from small fluctuations the size range greater. than 10p, and it has in dustfall appears to be an exercise in fu- mainly been reported in short tonsper tility. Dustfall is complex, being affected by square mile per month, arrived at by extra- the, number of unvegetated vacant lots, ve- polation from a jar a few inches in diam- hicular traffic, uncontrolled heavy industry, eter to a square mile. Metric units are pref- and wind velocity. Dustiness of the environ-

16 t

ment is an obvious nuisance and a compo- amount of smaller particles. During an in- nent of the economic cost of pollution. vestigation of atmospheric protein, a small cyclone separator was used ahead of a high- F.SAMPLING AND ANALYSIS OF volume sampler. Particles exhausted through ATMOSPHERIC PARTICULATE the cyclone outlet were collected on a filter of MATTER the high-volume sampler. The samples col- I.Particles Larger Than 10p lected on the filter of the combination unit Particles larger than 10p exist in the at- averaged about one-half the weight of those mosphere in very low numerical concentra- collected at the same time on the filter of a tions.The high concentrations that are high-volume sampler with no cyclone at- sometimes found in ducts or in work spaces tached. are the province of industrial hygiene and A few studies 32-34 have used long horizon- are not considered here. tal tunnels as fractional elutriators to deter- Since the largest particles have appre- mine particle size distributions. The elutria- ciable settling velocities and impact readily tor acts as a prefilter for the removal of at low velocities, they are usually determined larger-sized particles in a manner similar to gravimetrically following collection by depo- the cyclone high-volume sampler combina- sition in a dustfall jar." Although a cylin- tion. Both the cyclone and the elutriator, op- drical jar .might be expected to collect the erating on aerodynamic principles, have a equivalent of the dust content of an air col- graded selectivity (Figure 1-6) rather than umn of its own diameter extending to the a sharp cut-off point at a specific particle size. top of the atmosphere, in fact the aerody- The size range of the particles which pene- namic effects of the jar edges, of the mount-. trate the elutriator but are retained on the ing brackets for the jar, and of adjacent filter at the outlet duct depends on the air- structures tend to complicate the collection flow rate through the system (Figure 1-6). pattern. Only relative significance may be Other methods for the selective removal of attached to the resulting data, and only then larger (nonrespirable) particles have been if conditions are carefully standardized."-2 described by Lippmann and Harris 38 and by (There is a legend of a city which decreased Roesler." its reported dustfall by half in a single year The first stag 3 of most cascade impactors 38 by changing the height of its dustfall jars collects particles larger than about 5 to 10p. from 8 to 20 feet above ground level.) There Since, except in very dusty atmospheres, the is no definitive study of the effect on meas- mass mean diameter' is smaller than this, col- ured dustfall of the height of the collector lections on the first stage will be meager un- above ground. less the sampling time is set specifically to Gruber " has successfully used an adhesive coating on the outside of cylindrical con- tainers to ascertain the wind direction corresponding to maximum dust content of the air. This often permits identification of major dust sources. Evaluation is visual. Euro- pean practice favors flat adhesive surfaces placed horizontally as dust collectors." The advantages are not apparent, and analogous studies using greased microscope slides for pollen collection have shown them to be highly variable in collection efficiency." 2 3 4 Cyclonic collectors have been employed in AERODYNAMIC SIZE. p combination with high-volume samplers for FIGURE1-0. Horizontal Elutriator Cut-off Charac- the selective sampling of particles." While teristics.' (This graph shows that the elutriator collects all particles larger than 314 diameter such collectors can remove virtually all parti- when operated at 10 cfm, but at 50 cfm some par- 'des above 511, they also remove a significant ticles as large as 7µ diameter escape.) Ati.1 17 give ample material. Adhesion of such large scribed can, unless carefully chosen, inter- particles is poor (Section B-1), so an ad- fere severely with characterization of the hesive may be necessary to avoid bounce-off particles. The standard techniques used to or reentrainment. analyze dustfall samples generally reveal A variation is a single-stage impactor with which elements are somewhere in the sample size discrimination developed by Dessens." without giving any informationas to which He used a coarse slit followed by a shaped particles contain which elementsor what channel to induce turbulent deposition of compounds these elements represent. Never- particles along a microscope slide witha theless, such general chemical composition size gradation from larger to smaller. data are often helpful. One simple type of It appears, therefore, that no presently chemical characterization which gives this used technique for the concentration meas- sort of information for particles larger than urement of particles larger than about 10µ is 10p, is morphological identification under the superior to a properly installed dustfall jar; microscope. Although this may be applied to this method is also the least expensive. How- smaller particles as well, it is most effective ever, the jar lacks time resolution since it in the largest size range. McCrone 4° has must usually be exposed for two weeks toa published a photomicrographic atlas of dust month to obtain a significant sample. Dust- components which should permit recognition fall jars should be more widely standardized, of up to 90 percent of the particles above 10µ and more study is needed of alternative in a typical urban sample. In the hands ofan means of sampling the largest particles in the experienced microscopist, this technique is atmosphere. Chapter 11 shows some correla- one of the most potent tools in dust analysis. tions of health effects with air pollution,us- X-ray diffraction techniques will identify ing dustfall as an index of air pollution. chemical compounds present rather than Any collection technique can providea merely the elements. sample for subsequent analysis, although the Dustf all levels have decreased in most adhesives used in many of the methods de- cities(Figure 1-7) and there is a trend 10

250 g 200 6 150 4 100 ****....0".0, so *".....4%. 2 ''TAPITTSBURGH T7:.-----__ PHILADELPHIA "'" eft. 4".".. CINCINNATI -. am. Mu, ems ""44416. 0 ....Alb.- "Lt. 1950 1955 1960 1965 FIGURE 1-7.Dustfall.Data for Six Cities. (This graph is from a U.S. Government publication,butthe original source of the data is unknown.)

18 ve toward abandoning routine dustfall measure- particle source, is very nearly a linear func- ments, as they may no longer be indicative of tion of mass concentration. A disadvantage pollution levels. This viewpoint is defensible, of the method is that a constant particle-size although, since excessive dustfall is one of distribution and composition must be as- the most noticeable nuisances consequent sumed. upon air pollution, there is public pressure to Other light-scattering instruments include abate high dust emissions (Chapter 7). totalforward-scattering and right-angle- scattering photometers as well as instru- 2.Particles 0.1tt to 10/4 ments which count and size individual parti- A single group of sampling and analysis cles.49 The latter consist of: methods generally serves for the size range 1. A sampling system which dilutes the from 0.1t to 10 &. This size range includes sample stream with purified air until both the bulk of the particulate mass. and a only one particle at a time is likely to large fraction of the numbers. The prepon- be in the sensitive portion of the de- derant optical effects also arise from parti- vice, cles in this portion of the size spectrum, and most of the estimation methods not involving 2. a light source and optics to illuminate collection are optical. Collection and analysis a small volume (a few mm3 at most) techniques in this size range have been- re- at a defined angle, viewed by Lodge " 42 and discussed in two 3. a phototube (usually a multiplier) chapters of the 1968 treatise, Air Pollution, sensitive enough to detect the indi- edited by Stern.49 44 vidual flashes of light as particles The simplest o.-.' Pl technique involves use pass the illuminated volume, and of a photometer vIdoped in its present form 4. a pulse height analyzer and counting by Volz 45 for determining air turbidity. A electronics. simple photocell is pointed at the sun through A number of other principles for size an- a series of small apertures and a glass filter alysis of particles without collection were peaking at a wavelength of 500 ,z. An attached surveyed during World War H and the im- sight and spirit level allow measurement of mediate postwar years, but none seem to sun angle, which corrects the reading for air have warranted commercial exploitation ex- layer thickness along the path between the cept one device to measure mobility in an instrument and the sun. A nomogram may electric field. This latter technique is more then be used to obtain the turbidity coeiffi- applicable to smaller particles and will be cient. Greater accuracy, if warranted, may discussed in that connection(see Section be achieved by using a computer; a simple G-3). program has been developed for the calcula- Cascade impactors 39 have been found to tion." McCormick'; found that turbidity be useful devices for simultaneously collect- measurements from the bottom and from ing and clasilfying particles throughout most the top of a high building gave, by difference, of this size range, thereby yielding consider- a reasonable estimate of the concentration of able information 99-33 on the urban aerosol the intervening particulate matter. This is size distribution of selected chemical com- the cheapest and simplest technique, although ponents including sulfate, lead, and other it cannot measure continuously nor can it be metals. Similar information has been ob- used at night or during cloudy weather. tained by use of a helical-channel centri- Next in complexity is the "nephelmneter" fuge 54-55 as a classifier. described by Charlson." This device meas- Goetz " has described a single-stage mov- ures light scattered by particles suspended in Eng-slide impactor with some novel features. a defined volume of air. It is illOminated by a It is part of a system which includes mirror- flash tube placed so that nearly the total solid surfaced collecting slides and incident dark- angle from full forward to direct back-scat- field microphotometry which is particularly tering occurs. Integral scattering is recorded well adapted to physical characterization of and, in the absence of a powerful nearby particles from roughly 0.21.4 to 2tt. Informa-

. 19 tion on coalescence tendency and heat lability methods have been studied. The visual color is easily obtained. of the spots may be compared with a stand- Spurny 58 has studied the application of ard gray scale. The reflectance may be meas- recently developed filter material to particle ured pintom :;.:ically. The transmittance of research. The filter is a plane film of polycar- light through both filter and deposit may be bonate which is exposed to fission fragments compared with transmittance through a clean and then treated to remove the radiation portion of the filter. Visual and reflectance damage. A number of pore sizes are avail- measurements determine the blackness of the able; the pores are uniform, straight, and cir- deposit, while transmittance measures a cular in cross section. The plane upper sur- function of all partfeles collected, and under face is ideal for both optical and electron mi- some circumstances measurements made by croscopy ( the latter after replication), and the two techniques may not be identical. For the filtration characteristics are excellent. example, a gram of magnesium oxide smoke The uniformity of the material commends its collected in a single spot would not be visibly use for gravimetric purposes and for "smoke gray and might even increase reflectance, but shade" determination. The only evident dis- would transmit no light at all. Urban particu- advantage at the moment is its price. late matter is not, however, pure magnesium Frank and Lodge 59 have described the use oxide, and, in fact, the three measures (vis- of electron microscopy for morphological ual, reflectance, and transmittance) gener- identification of several species of particles ally correlate fairly well in the short run. smaller than 1p. Although the technique is Over longer periods, the introduction of new not so broadly applicable as is optical mi- sources and the removal of old ones may be croscopy of dusts, it may permit some an- expected to change the cemposition of the alyses, including the identification of sulfuric particles enough to cause divergence of the acid droplets below 1p. different techniques. For example, if a resi- In view of the extensive literature involv- dential area abruptly converts from coal ing filter tape and high-volume samplers, heating to gas, the virtual disappearance of some further discussion of these devices is in soot will have an enormous effect on reflect- order, especially since air quality criteria ance which may not appear so strikingly in must ultimately relate to accurate measure- transmittance. ments. Both samplers are inexpensive and Transmittance is by no means a unique durable, and both provide data which have function of the total concentration of partic- stringent limitations that are not always ulate matter. Stalker et al." compared trans- understood. mittance and particle concentrations in different parts of Nashville, Tennessee. The a. Tape Samplers for Suspended Particulate slopes of the regression lines varied by a fac- Matter tor greater than three, and at some locations The tape sampler most widely used in the 1:0 correlations appeared to exist between the United States has been the AISI (American two measurements. Iron and Steel Institute) sampler developed Additional complications arise in three by Hemeon and his colleagues.6° Other ver- ways. First, none of the methods of measure- sions exist, but all are alike in function. A ment exhibit a linear relationship between series of portions of filter paper, usually suc- the quantity determined and the number of cessive areas of a paper tape, are positioned particles collected. Reflectance changes will so as to be clamped between an intake tube depend on whether later deposits are re- and a vacuum connection. Air is drawn tained on the surface of, or penetrate deeply through the filter for a selected time, usually into, the layers first deposited. Measurements one to four hours, and a new portion of tape of transmittance are similarly dependent on is then moved into position and sampling is whether an added increment simply adds resumed. thickness to the collected deposit or fills pores The fundamental basis of evaluating sam- and gaps, thus increasing the bulk density ples is optical, although a few nonoptical but not the thickness of the layer.

20 Second, the rate of sampling is not con- total particle concentration in the air but to stant but depends on the amount of material the concentration of "dark suspended mat- already collected and the structure of the ter" resulting primarily from combustion. deposit." Hence the assumption of a constant The darkness of the stain, as measured by a sampling rate will be seriously in error, es- reflectometer, is converted to surface concen- pecially for heavy deposits. Averaging initial tration of smoke by means of a calibration and final sampling rates, or recording the curve. The derived surface concentration is sampling rate continuously, represent im- then translated into an ambient concentra- provements at the cost of greatly increased tion using the relationship: attention to the instrument, or of increased SA complexity and expense. C= (1-2) Third, reflectance methods lose all discrim- V ination beyond a certain deposit density. where C = the concentration of smoke in the Once the filter is covered with particulate air (µg /m3), matter, only the exposed. surface of the de- S = the derived surface concentration posit affects the reflectance; the reflectance (pg/cm3), then become a measure of the composition, A = the area of the filter stain (cm2), but not the amount of material collected. This and problem is recognized, but not solved, in a V = the volume of air sampled (m3). proposed European standard method." Experimental work on the form of the Transmittance, which is most widely,meas- calibration curve for deriving surface con- ured in the United States, is normally concentrations has been carried out in France, verted into units of coh's per thousand linear the Netherlands, and the United Kingdom. feet of air passing through the filter. Coh Working Party on Methods of Measur- stands for "coefficient of haze." A coh unit is ing Air Pollution and Survey Techniques of defined as that quantity of light-scattering the Organization for Economic Cooperation solids (on the filter) which produces an opti- and Development has proposed a Standard cal density equivalent of 0.01 when measured International Calibration Curve (the mean by light transmission. Optical density is de- of the curves developed in the three countries fined as the common (decadic) logarithm of listed above) as well as a standard sampling the opacity (inverse of fractional transmis- and measurement procedure." sion). Thus if one-fifth of the incident light The use of the conversion curves to make is transmitted through the paper, as com- international comparisons is potentially dan- pared with clean paper, the opacity is five. gerous. The method has the disadvantage of A coh measurement is routinely reduced to credibility; that is, it is too easy to overlook coh per 1,000 linear feet of air passing the arbitrary nature of the units, and to be- through the filter tape by dividing the unre- lieve that actual airborne particle concen- duced coh value by the number of thousands trations have been measured. This is of con- of feet actually drawn in the test. cern for those areas of the United States for For reflectance, a RUDS test is made by which air quality standards already exist; in measuring the percentage reflectance of the most cases the standards include separate filter tape and similarly reducing the meas- values for "airborne particulate matter" ex- urement to 1,000 linear feet of air. Reflect- pressed in gravimetric units, and for "atmos- ance of clean paper tape is the reference pheric soiling" determined by transmittance standard, set at 100 on the reflectometer. or reflectance measurements on deposits of RUDS is an acronym for "reflectance unit of the sort described here. dirt shade." For. many purposes, theInternational Reflectance measurements are used in vari- Standard Calibration Curve will be found in- ous European countries for calculating am- convenient. It is the empirical product of a bient air concentrations of "smoke" or "dark complex physical phenomenon (light absorp- suspended matter." The darkness of the tion and scattering) and an arbitrary instru- filter stain is not considered proportional to ment response: The curve is not a !33 21 matical one, and hence computer reduction of thetic organic fiber. Since the fibers are sub- data is made awkward. stantially less than 1K in diameter, these fil- Still other conversion formulae have been ters are highly efficient despite their open suggested by Kemeny " in South Africa, by structure and consequent low resistance to Ellison 68- in England, and by Sullivan 66 in airflow. Samples are normally collected for Australia. These workers, following Clark," 24 hours and sampling rates are measured at have attempted to convert their readings the beginning and end of the period. mathematically into units of milligrams per Since the filters are weighed before use, it cubic meter of "smoke" in the air. As Sander- is possible to determine the weight of col- son and Katz 68 have correctly stated, "There lected material if one standardizes the weigh- is considerable doubt whether a truly satis- ing conditions, optimally at 25°C and at rela- factory expression exists for the translation tive humidities below 50 percent. Thereafter, of optical density readings into units related samples may be extracted, heated,or in- to smoke and haze concentrations." The re- cinerated, and determination can be made of sults of Stalker et aL," previously mentioned, organic content, carbon, minerals or any suggest that this may be an understatement. other .suitable and/or interesting fraction, The method yields only an index of and not a element, or substance. The collected sample measurement of absolute concentrations of is the particulate content of approximately suspended particulate matter. 2,000 m3 of air, and is large enough for Notwithstanding its limitations, the tape nearly any sort of analysis, although care sampler is cheap, simple, and rugged, and it must be used in interpreting the data. There will certainly continue to be used. It should, area few studies on interactions between col- however, be used with the knowledge that its lected species, loss through volatilization, and measurements, in whitever units, are arbi- similar problems. The performance charac- trary and .artificial and without absolute teristics of high-volume samplers today are meaning. Their relative values can be useful quite well understood, thot/Eik reactions on if the samplers, as well as their locations, sampler filters are not. their installation, and the technique ofmeas- Many analyses are plagued by the lack of a urement, are rigorously standardized. Fur- universally applicable filter material. Glass thermore, it must be kept in mind that long- fiber filters are convenient for determining term trends may reflect changes in com- total particle concentration. However, the position as well as in amount of airborne very fine glass fibers are water and acid sol- particles. uble, and the glasscontainssignificant amounts of a large number of metals, as well b. High-Volume Samplers for Suspended as sulfate, silicate, and other anions. ,Hence Particulate Matter inorganic analyses are performed over a The.original high-volume sampler con- background from the filter which. is by no sisted of the motor and blower of a tank-type means constant. Polystyrene fiber filters can vacuum cleaner, suitably enclosed and fitted be made extremely low in inorganic content, with a holder for flat filter paper in place of ,but are virtually useless for organic analysis. a dust bag. Present versions are more re- Membrane filters .are very useful in special fined, but little different in. concept. The use applications, e.g., when alkaline metals are to of a blower necessitates a filter of large areas be determined. and low air resistance, and also makes the Suspended particle concentrations, deter- sampling rate very dependent on the mass of mined by high-volume samplers in urban material collected. areas, are shown in Table 1-2. The column Current samplers 30 are generally exposed listing "Benzene soluble organic particles" is inside a case which places the filter surface a measure of the organic particulate matter horizontal, facing upward, under a roof in the total sample. Much of this material is which keeps out rain and snow, and generally derived from the incomplete combustion of prevents collection of particles larger than fuels. The data on organics may be further about 1001A. Filters are felts of glass or syn- analyzed for polycyclic aromatic hydrocarbon 22 Yr

content; a possible significance of these com- The electron microscopic methods of Frank pounds in carcinogenesis is discused in Chap- and Lodge," and the earlier work of Tufts ter 10. and Lodge," provide some insight into the chemical composition of the particles, al- 3.Particles Smaller Than 0.1p though even in the most favorable cases, the authors were able to account for the com- Several techniques have been used sys- position of less than half of the particles tematically for the characterization of parti- seen. cles smaller than 0.1p.. 1. Saturation of the air and subsequent G. rapid expansion to cause a high su- SIZE, CHEMICAL COMPOSITION, AND persaturation: the resulting droplet SOURCE STRENGTHS OF PARTICULATE count is assumed equal to the total MATTER FROM SELECTED EMISSION particle concentration. Successively SOURCES smaller degrees of supersaturation A listing of source strengths is given in presumably activate only larger parti- Table 1-6. Composition of particles and, cles to act as nuclei. Size spectra may where available, data on particle size distri- be generated in this way, although the bution from various sources follow. results do not necessarily agree with those of other methods. Most of the 1.Open-Hearth Furnaces available data were obtained by this technique." a. Chemical Composition 2. Passage of the air through a long Analysis" of particulate emissions froma narrow channel: The smallest parti- 200-ton oxygen-lanced open-hearth furnace, cles will be removed most rapidly by a composite sample for all process stages, in- diffusion, and the extend of the ef- dicates the following chemical composition: fect can be calculated." Differential condensation nuclei counts after dif- Compound Percent ferent diffusion lengths permit deter- Fe203 89.1 mination of a size spectrum. Fe0 1.9 3. Measurement ofthe mobilityof Si02 0.9 charged particles in an electric field: A103 0.5 It is necessary to assume or to com: Mn0 0.6 pute the efficiency of electrical charg- Alkalis 1.4 ing of these smallest particles to de- P205 0.5 rive numbers and effective sizes. Orr S 0.4 and his coworkers " used this method Fluorides may be present in open-hearth fur- to study changes in the size of hygro- nace particulate emissions if fluorspar fluxes scopic particles with relative humid- or fluoride-containing ores are used. 'While ity, and 'Whitby 72 has set up a facility fluoride emissions are generally insignificant, for obtaining count-size distributions problems have been reported in the vicinity of particles in air, using a series ofof at least one plant which uses fluorspar instruments with overlapping ranges. fluxes and one which uses an ore witha high 4. Electron microscopic techniques have fluoride content." been used to obtain particle countsas well as' information on the size and b. Particle Size Morphology of these small particles. By number, the majority of particles emit- Of these methods only the electrical mobil- ted by an open-hearth furnaceare below ity separator has been used 71 for chemical 0.1A in diameter." Size analysis " ofa com- characterization of particles below 0.1p, but posite sample over the entire hearth little analytical information is now available. cated the following distribution:

28 Diameter Weight percent cinerators in Los Angeles " indicated 20 per- (1z) less than stated size cent by weight of the discharge to be con- 2 20 densable and approximately 5 to 15 percent 5 46 of the condensate to be sulfuric acid. The 10 68 remaining 80 percent was particulate mat- 20 85 ter containing silicon, lead, aluminum, cal- 40 93 cium, iron, and traces of other eliments. 2.Incineration Particulate samples from the stack effluent a. Chemical Composition of municipal incinerators in Milwaukee," Analysis of emissions from municipal in- asked and subjected to spectographic and

Table 1-6.EMISSION FACTORS FOR SELECTED CATEGORIES OF UNCONTROLLED SOURCES OF *- PARTICULATES.

Emission source Emission factor

Natural gas combustion: Power plants 15 lb/million ft' of gas burned Industrial boilers 18 lb/million ft' of gas burned . Domestic and commercial furnaces 19 lb/million fts of gas burned Distillate oil combustion: Industrial and commercial furnaces 15 lb/thousand gallons of oil burned Domestic furnaces 8'lb/thousand gallons of oil burned Residual oil combustion: Power plants 10 lb/thousand gallons of oil burned Industrial and commercial furnaces 23 lb/thousand gallons of oil burned Coal combustion: Cyclone furnaces 2X (ash percent) lb/ton of coal burned Other pulverized coal-fired furnaces 13-17X (ash percent) lb/ton of coal burned Spreader stokers 13X (Ltsh percent) lb/ton of coal burned Other stokers 2-5X (ash percent) lb/ton of coal burned Incineration: Municipal incinerator (multiple chamber) 17 lb/ton of refuse burned Commercial incinerator (multiple chamber) 3 lb/ton of refuse burned Commercial incinerator (single chamber) 10 lb/ton of refuse burned Flue-fed incinerator 28 lb/ton of refuse burned Domestic incinerator (gas-fired) 15 lb/ton of refuse burned Open burning of municipal refuse 16 lb/ton of refuse burned Motor vehicles: Gasoline-powered engines 12 lb/thotisand gallons of gasoline burned Diesel-powered engines 110 lb/thousand gallons of diesel fuel burned Grey iron cupola furnaces 17.4 lb/ton of metal charged Cement manufacturing 38 lb/barrel of cement produced Kraft pulp mills: Smelt tank 20 lb/ton of dried pulp produced Lime kiln 94 lb/ton of dried pulp produced Recovery furnaces b 150 lb/ton of dried pulp produced Sulfuric acid manufacturing 0.3-7.5 lb. acid mist/ton of acid produced Steel manufacturing: Open-hearth furnaces 1.5-20 lb/ton of steel produced Electric arc furnaces 15 lb/ton of metal charged

a For more detailed data, consult "Control Techniques for Particulate Air Pollutants," U.S. Department of Health, Education, and Welfare, Dec. 1968 b With primary stack gas scrubber 24 wet chemistry analysis, had the following Diameter Weight percent composition: (p) less than stated size 5 6.0 SPECTOGRAPHIC ANALYSIS 10 20.5 Elements reported in percent of (felted material 20 47.2 Element Percent 30 68.7 Calcium 10 + 44 89.2 Silicon 5 + Sodium 1-10 3.Sulfuric Acid Manufacture: Chamber Nickel 1-10 Process Aluminum 1-10 a. Chemical Composition Zinc 1-10 Magnesium 1-10 Acid mist emissions contain sulfuric acid Titanium 0.5-5.0 and dissolved nitrogen oxides. The nitrogen Iron oxides constitute approximately 10 percent 0.5-5.0 by weight of total acid mist emissions. Barium 0.1-1.0 Small amounts (less than 1 percent) of man- b. Particle Size ganese, chromium, copper, vanadium, tin, sil- The weight percentage of acid mist par- ver, boron, beryllium, and lead were present. ticles less than 3p in diameter found in samples from two chamber acid plants, one using WET CHEMICAL ANALYSIS molten dark sulfur and one using solid sul- Percent fur, were 10.1 percent and 3.5 percent re- Phosphorus 1.46 spectively. Silicate Phosphates 0.88 4.Sulfuric Acid Manufacture: Contact Nitrates 0.62 Process " Sulfates 5.0 a. Chemical Composition. Chlorides 0.02 Discharge gases contain sulfuric acid mist Analysis of fly ash collected at three New as well as unabsorbed sulfur trioxide, which York Te incinerators and of that.emitted from converts to acid mist upon reaching the at- their stacks showed the following chemical mosphere. Trace amounts of nitrogen ox- composition: ides may arise if the fuel used in the proc- Weight percent ess contains nitrogenous matter. Collected Emitted Silicon as Si02 49.5. 36.3 b. Particle Size Aluminum as ,A1208 22.9 25.7 In plants where particle size has been de- Iron as Fe208- 6.3 7.1 termined, the weight percentage of particles Calcium as Ca0 8.8 8.8 3p or less in diameter leaving the absorber Magnesium as Mg0 .2.2 2.8 unit ahead of any mist recovery equipment Sodium as Na20 6.0 10.4 ranged from 7.5 percent to 95 percent. The Potassium as K205 mean percentage was 63.5. Titanium as TiO2 1.3 0.9 When oleum is produced, the proportion Sulfur as SO8 3.0 8.0 of acid mist particles smaller than 3p in di- b. Particle Size ameter increases. In one plant, the percent- Analysis of the, particulate emissions from age rose from 9.5 percent to 54 percent. the Los Angeles municipal incinerators indicated 30 percent (by weight) of the par- 5.Cement Plants ticles were less than 5p in diameter. Particle a. Chemical Composition size analysis of the samples collected at the Chemical analysis of the raw kiln feed Milwaukee ?8 incinerators showed the fol- dust and the kiln dust from the precipitator lowing distribution: outlet of portland cement plants in the Le-

25 high Valley, Pennsylvania, region showed 2PbC1Br and 2NH4C1. PbC1Br. Particulates the following composition: discharged through the blowby consist almost entirely of unchanged lubricating oil." Weight percent b. Particle Size Raw kiln Dust from feed dust precipitator Analysis" of diluted exhaust from automo- Compound* (Average foroutlet (Average biles operated at crusing conditions showed three types of three of cement) samples) a particle concentration of 40 to 52pg per Ca0 40.9 liter of exhaust. From 62 to 80 percent of the CaCO3 75.9 particulate mass consisted of particles with SiO, 13.4 18.8 aerodynamic diameters below 2µ at unit den- A1203 3.7 7.1 sity. The lead content of particulate emis- Fe20, 2.1 9.6 sions averaged about 40 percent and ap- Mg0 2.5 peared to be independent of particle size. Na20 1.1 Measurements 84 with undiluted auto exhaust K20 7.3 indicate that about 90 percent by weight of Mn0 0.2 exhaust lead is contained in particles with TiO2 0.1 diameters below 0.5p. CuO Trace 7.Fuel Oil Combustion Ignition Loss.... 12.7 a. Chemical Composition No determination of sulfur made. The probable constituents 85 of fly ash from oil combustion have been identified as A1203, b.. Particle Size Al2( SO4)8, CaO, CaSO4, Fe208, Fe2(SO4)8, Examples of the distribution of particle MgO, MgSO4, NiO, NiSO4 Si02, Na2SO4, sizes in cement plant raw kiln feed and kiln NaHSO4, Na2S207, V203, V20V205, ZnO, emissions are indicated below: ZnSO4, Na2CV205, 2Na20 .V205, 3Na20205, 2NiO.V205, 3NiO.V205, Fe202705, Fe20 Raw kiln feed Kiln emissions Diameter weight percent weight percent 2V202, Na20V204.5V202 and 5Na2O204 (u) less than stated sizeless than stated size 11V202. Ref. 81 Ref. 81as Ref. 1 Analysis " of fly 'ash ,from a plant using 60 81.4 97-100 residual oil .produced Cite; following percent- 50 73.1 95-100 age composition: 40 63.8 96.5 85-95 Test A Test B 30 53..3 Total :AidsTotal solids 92.9 70-90 from burn- from burn- 20 41.5 84.6 50-70. ing PS 400 ing 4° API 10 23.5 56.3 oil (Col- oil (Col- 30-55 lected in a lected in a 5 10.8 15.5 20-40 Element laboratory glass 2.5 Electrical filter sock 10-35 `precipitatorat 300°F) Average of two samples at 230°F) (Weight (Weight percent) percent) 6.Motor Vehicles Carbon 58.1° 18.1 a. Chemical Composition Ether Soluble 2.3 4.4 Ash (900°C) 17.4 51.2 Particles contained in vehicle exhaust in- Sulfates as SO2 clude lead compounds, carbon particles, motor 17.5 25.0 (Including H2SO4) oil, and nonvolatile reaction products formed Iron as Fe202 3.1 3.7 from motor oil in the combustion zone.' The Nickel as Ni0 reaction products include high molecular 1.8 13.2 weight olefins, carbonyl compounds (alde- Vanadium as V203 .2.5 4.7 Silicon as Si02 0.6 9.7 hydes and ketoneS), and free acids. Lead Aluminum as A1203 particles in the exhaustare principally in the 1.6 14.9 Sodium as Na20 0.9 3.0 from of PbC1Br, the wand /3 forms of NII4C1. a May include some hydrogen '26 Less than 1 percent of the following ele- found in four investigations, each of which ments or compounds was present: Cl, NO3, reports wide ranges also. Cr02, Co20v BaO, MgO, PbO, CaO, CuO, Percentage Ti02, MoO2, B208, Mn02, ZnO, P202, SrO, Compound of fly ash TiO. Carbon, C 0.37-36.2 Iron (as Fe03 or Fe,04) 2.0 -26.8 b. Particle Size Magnesium (as Mg0) 0.06- 4.77 A literature survey 81 of the size distribu- Calcium (as Ca0) 0.12-14.73 tion of particles emitted by large oil-burning Aluminum (as A1203) 9.81-58.4 units gave the following results: Sulfur (as SO,) 0.12-24.33 Titanium (as TiO2) 0- 2.8 SIZE DISTRIBUTION Carbonate (as CO3) 0- 2.6 (Percent by number) Silicon (as Si02) 17.3 -63.6 Phosphorus (as P202) OA to 11, /A to 2p, 2p, to Sp 5 + p, Largest size 0.07-47.2 Potassium ( as K20) 2.8 - 3.0 48.4 28.8 16.7 6.1 15p. Sodium (as Na20) 0.2 - 0.9 64.2 18.8 10.0 7.0 15p. Undetermined 0.08-18.9 93.5 .3.2 2.0 1.3 20p. a Ignition loss 94.8 2.2 1.5 1.0 20p. b. Particle Size One reference indicated 47 percent, by weight, was less than 3p. diameter. Estimated particle size distributions " for four broadclassificationsof combustion 8.Combustion of Coal88 equipment are listed below. All distributions represent the size of the particles leaving the a. Chemical Composition boiler or furnace before any control equip- The following ranges in chemical composi- ment. The distributions reported for all four tion were indicated by analysis of fly ash equipment classifications ranged widely; emissions from a variety of coal combustion those shown 'in the table are considered units. The figures are the extreme values "typical." WEIGHT PERCENT LESS THAN STATED SIZE Spreader Stoker-Fired Particle Size Pulverized Fuel Cyclone Stoker-Fired (Other-than (p.) Fired Furnace Furnace Furnace Spreader) 10 30 76. 10 7 20 50 83 20 15 40 70 90 37 26 60 80 ..92 47 36 80 85 94 54 43 100 90 95 60 50 200 96 97 66 H. SUMMARY vidual aggregates are larger than single Aerodispersed solid and liquid particles molecules (about 0.00020; but smaller than constitute a significant fraction of the pollut- about 500/. diameter; ants found in urban atmospheres. Such par- Atmospheric particles have size-dependent ticulate matter vary greatly in chemicalcom- dynamic, optical,, and electrical properties, position and consist of multirnolecular assem- and are characterized by such surface activi- blies that may, range in complexity from salt ties as sorption, nucleation, and adhesion. crystals and acid droplets to heterogeneous Particles, in the size range below 0.1p. dis- liquid and solid aggregates and living cells. play a behavior similar to that- of molecules In this document, a particle is any dispersed and are :characterized by large. random mo- matter, solid or liquid, in which the indi- tions caused by collisions with gas molecules. 09, 27 In addition, they frequently collide with each Dustfa ll measurements provide a rough other and form larger aggregates. Particles index of those particles which readily settle larger than 1p have significant settling veloci- out of the air. Typical values encountered in ties; their motions deviate from the motion urban areas range from 0.35 mg/cm2-month of the air in which they are borne, and their to 3.5 mg/cm2-month (10 tons/mi2-month to rates of coagulation into larger aggregates 100 tons/mi2-month) while values approach- are low. The aerodynamic behavior of parti- ing 70 mg/cm2-month (2000 tons/mi2-month) cles with diameters from 0.1p to 1/A, is transi- have been measured close to very severe tional between these two regimes. Particles sources. Levels of dustfall have apparently larger than 10p have rapid settling velocities declined in cities, and dustfall measurement and therefore remain in the air for relatively is probably not useful as an index of overall short durations. The size range between 0.1p particulate levels. Nevertheless, dustfall it- and 10p accounts for the bulk of the particu- self constitutes a nuisance, and its measure- late mass in the atmosphere. ment provides some indication o1 urban Particles below 0.1p obey the same laws of dirtiness. light scattering as molecules do and their ef- A number of methods are available to fects on visibility are inconsequential. Parti- measure the mass concentration of suspended cles very much larger than 1/A, obey the same particles. Optical techniques, such as the sun optical laws as macroscopic objects, inter- photometer, the integrating nephelometer, cepting or scattering light roughly in propor- and light-scattering counters, provide an in- tion to their cross-sectional area. Particles dication of particle concentrations in the size between 0.1p and a few microns obey the very range from 0.1p to 10p. Two of the most com- complex scattering laws set forth by Mie. mon instruments for measuring mass con- This is the particle size range that is most ef- centrations are spot samplers and high-vol- fective in scattering light. (See Chapter 3.) ume samplers. In the former, air is drawn Particles in the atmosphere can be said to through an exposed portion of a paper tape; originate by two types of mechanism. Small then the tape is moved to expose another particles in the size range below 1p, arise prin- spot. The spots that result on the tape are cipallyby condensation and combustion, evaluated optically by measuring their light while the larger particles with the exception reflectance or transmittance. Although the of rain, snow, hail, and sleet, result from spot sampler is cheap, simple, and rugged, its comminution. Although the chemical compo- use is better suited to the determination of sition of particles below 0.1p diameter has relative rather than absolute mass concen- not been widely studied, the increase over trations. High-volume samplers employ a natural levels of particles in this size range blower which "sends air through a special seems to be entirely due to combustion. Com- filter over a specified time period. By weigh- bustion products and photochemical aerosols ing the material collected by the filter, the makeup a large fraction of the particles in mass concentration can be readily deter- the range of 0.1-1.& to 1-p, diameter. Particles mined; chemical analyses also can be carried between 1/A, and 10µ generally include local out. High-volume sampling is the method of soil, fine dusts emitted by industry and, at choice for measuring particulate levels. As maritime locations, airborne sea salt. Indus- with any other point-sampling method, the trial sources of particulate matter include location of the sampling instrument is very municipal incineration, cement plants, steel critical, and data for an entire city should not mills, sulfuric acid manufacturing, industrial be based on a single sample located at a furnaces, kraft pulp mills, and others. Parti- single place. cles larger than 101..i, diameter frequently re- Most of the data on suspended particulates sult from mechanical processes such as high, come from the National Air Surveillance Net- way construction, wind erosion, grinding, work (NASN), which employs the high-vol- spraying, etc., and include material that is tune sampler. NASN currently consists of dropped on the ground and pulverized by ve- about 200 urban and 30 nonurban stations, hicles and pedestrians. and it is supplemented by State and local 28 40 networks. Based on these data, annual geo- tion in Environmental Science and Technology.) metric mean concentrations of suspended 11. Preining, 0., Sheesley, D., and Djordjevic, N. "The Size Distribution of Aerosols Produced by particulate matter range from 60 pg/m3 to Air Blast Nebulization." J. Colloid Interface Sci., about 200 pg/m3 in urban areas. The maxi- Vol. 23, pp. 458-561, 1967. mum average concentrations for 24-hour 12. Day, J. A. "Small Droplets from Rupturing Air- periods is about 3 times the annual mean Bubble Films." J. Rech. Atmospheriques, Vol. 1, with values of 7 times the mean occurring in pp. 191-196, 1963. about 2 percent of the communities. In gen- 13. "New York-New Jersey Air Pollution Abate- ment Activity, Phase IIParticulate Matter." eral, mean particulate concentrations corre- U.S. Dept. of Health, Education, and Welfare, late with urban population class, but there is National Center for Air Pollution Control, Cin- a wide range of concentrations within each cinnati, Ohio, December 1967. urban population class, and many smaller 14. "Washington, D.C. Metropolitan Area Air Pol- communities have higher concentrations than lution Abatement Activity." U.S. Dept. of Health, Education, and Welfare, National Center for Air larger ones. In nonurban areas, typical geo- Pollution Control, Cincinnati, Ohio, 1967. metric mean concentrations range between 15. Venezia, R. and Ozolins, G. "Air Pollutant Emis- 10 pg/m3 and 60 pg/m3. sion Inventory. Interstate Air Pollution Study, Phase II Project Report." U.S. Dept. of Health, I.REFERENCES Education, and Welfare, National Center for Air 1. Kreichelt, T. E., Kemnitz, D. A., and Cuffe, S. T. 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Air Pollution Control (Presented at the National Incinerator Con- Assoc., Vol. 10, pp. 303-306, 1960. ference, American Society of Mechanical Engi- 63. "Methods of Measuring Air Pollution. Report of neers, New York, May 20-24, 1966.) the Working Party on Methods of Measuring 79. Kaiser, E. R. "Refuse Composition and Flue Gas Air Pollution and Survey Techniques." Organi- Analyses from Municipal Incinerators." Proc. zation for Economic Cooperation and Develop- Natl. Incinerator Conf., American Society of Me- ment, Paris, France, 1964, 94 pp. chanical Engineers, 1964. pp. 35-51. 64. Kemeny, E. "The Determination of Gravimetric 80. "Atmospheric Emissions from SulfuricAcid Pollution Concentrations by Means of Filter Manufacturing Processes. A Cooperative Study Paper." J. Air Pollution Control Assoc., Vol. 12,. pp. 278-281, 1962. Project of the Manufacturing Chemists' Associa- 65. Ellison, J. M. "Die Schlitzung der Konzentration tion, Inc." U.S. -Dept. of Health, Education, and teilchenformiger Welfare, Div. of Air Pollution, Cincinnati, Ohio, Luftverunreinigungendurch PHS-Pub-999-AP-13, 1965. Bestimmung des Verschmutzungsgrades von Fil- tertapieren." Staub, Vol. 28, pp. 240-246, 1968. 81. Doherty, R. E. "Current Status and Future Pros- 66. Sullivan, J. L. "The Calibration of Smoke Den- pects, Cement Mill Air Pollution Control." Proc. sity." J. Air Pollution Control Assoc., Vol. 12, Natl. Conf. Air Pollution,Washington,' D.C., pp. 474-478, 1962. 1966, pp. 242-249. 67. Clark, J. G. "Calibration of Dr. Owen's Appara- 82. "Motor Vehicles, Air Pollution, and Health. A tus, for the Estimation of Suspended Solid Pollu- report of the Surgeon General to the U.S. Con- tion in the Atmosphere. Report on Observations gress." U.S. Dept. of Health, Education, and in the Year 1966-67." Advisory Committee on Welfare, National Center for Air Pollution Con- Air Pollution. trol, Washington, D.C. 1962. 68. Sanderson, H. P. and Katz, M. "The Optical 83. Mueller, P. K., Helwig, H. L., Alcocer, A. E., Evaluation of Smokes or Particulate Matter Col- Gong, W. K., and Jones E. E. "Concentration of lected on Filter Paper." J. Air Pollution Con- Fine Particles and Lead in Car Exhaust." Amer- trol Assoc., Vol. 13, pp. 476-482, 1963. ican Society for Testing and Materials, Spec. 69. Rich, T. A., Pollak, L. W., and Metnieks, A. L. Tech. Pub. 352,1964, pp. 60-73. "Estimation of Average Size of Submicron Par- 84.Lee, R. E., Jr., Patterson, R. K., Crider, W. L., ticles from the Number of All and Uncharged and Wagman, J. "Concentration and Particle Particles." Geofis. Pura Appl., Vol. 44, pp. 233- Size Distribution of Particulate Emissions in 241,1959.. Auto Exhaust." 1968. (Manuscript in Prepara- 70. Megaw, W. J. "Recent Research on Small Ions tion). andAitken.Nuclei." J. Rech. Atmospheriques, 85. Bowden, A. T., Draper, P., and Rowling, H. "The Vol. 2, pp.. 53-68, 1966. Problem of Fuel Oil Deposition in Open Cycle 71. Orr, C., Hurd, F. K., Hendrix, W. P., and Junge, Gas Turbines." Am. Inst. Mech. Engrs. Proc., C. E. "The Behavior of Condensation Nuclei Vol. 167, pp. 291-300, 1953. under Changing Humidities." J. Meteorol., Vol. 86. MacPhee, R. D., Taylor, J. R. and Chaney, A. L. 15, pp. 240-242, 1958. "Some Data on Particles from Fuel Oil Burn- ., ing." Air Pollution Control District, Air Analysis nati, Ohio, PHS-Pub-999-AP-2, November 1962. Division, Los Angeles, California, Analysis Paper 88. Smith, W. S. and, Gruber, C. W. "Atmospheric 7, November 18, 1957. Emissions from Coal Combustion. An Inventory 87. Smith, W. S. "Atmospheric Emissions from Fuel Guide." U.S. Dept of Health, Education, and Oil Combustion." U.S. Dept of Health, Educa- Welfare, Div. of Air Pollution, Cincinnati, Ohio, tion, and Welfare, Div. of Air Pollution, Cincin- PHS-Pub-999-AP-24, April 1966. Chapter 2

EFFECTS OF ATMOSPHERIC PARTICULATE MATTER ON SOLAR RADIATION AND CLIMATE NEAR THE GROUND Table of Contents Page A. INTRODUCTION 35 B. EFFECTS OF PARTICULATE MATTER IN THE ATMOSPHERE ON VISIBLEMADIATION 35 C. EFFECTS OF PARTICULATE MATTER IN THE ATMOSPHERE ON TOTAL SOLAR RADIATION 38 1. Physical Factors 38 2. Seasonal Variations 39 3. Weekly Variations 39 4. Other Variations 40 D. INFLUENCE ON PRECIPITATION 40 E. RELATION TO WORLDWIDE CLIMATE CHANGE 42 F. SUMMARY 43 G. REFERENCES 44 List of Figures Figure 2-1Relation of Solar Transmissivity to Height Above Ground in "Pol- luted" and "Clean" Areas 36 2-2Annual Variation of the Ratio of Illumination Levels in Central Lon- don and at Kew (*), and of Concentration of Particulate matter at kew (o) 37 2-3Causes of Cyclical Diurnal Smoke Variations 41 2-4Yearly Cycle (Averaged Over Six Years) of Deposited Pollutants 41 2-5Precipitation Values at Selected Indiana Stations and Smoke-Haze Days at Chicago 42 List of Tables Table 2-1Approximate Association Between Atmospheric Aerosol Concentra- tions and Relative Solar Radiation Levels 39 2-2Loss of Sun's Radiation in Three European Cities Over That in the Adjacent Country 40 2-3 Mean Number of Condensation Nuclei for Various Ranges of Dust Concentrations in City Air 40

84 Chapter 2 . EFFECTS OF ATMOSPHERIC PARTICULATE MATTER ON ,SOLAR RADIATION AND CLIMATE NEAR THE GROUND

A. INTRODUCTION come massive enough to fall from the base of the cloud as rain. Particles in the atmosphere play several Another kind of particle is required to roles in the behavior and determination of stimulate the rapid transformation of cloud the weather. Among the most obvious is the droplets into precipitation in supercooled effect they have on the radiation from the (subfreezing) parts of clouds. Such particles sun: They scatter the light to greater or lesser are termed freezing nuclei. Without these, extents in different wavelength regions, de- the water droplets would not freeze except pending on their size, character, and concen- at temperatures below 40°C. Once frozen, tration, and thus provide- the sky with its small ice particles grow rapidly at the ex- variable hues, its colorful dawns and sunsets, pense of the surrounding water droplets and and also dense hazes and dark urban palls. begin to fall as snow. They may later melt to More subtle changes are occasioned by parti- become rain. Dramatic changes in cloud cles when they reduce the amount of solar en- structure have been achieved by seeding su- ergy that reaches the ground. persaturated clouds with appropriate freez- Particles play a less advertised but very ing nuclei. There is evidence, discussed below, essential role in the formation of clouds. that some observed changes in precipitation Without them, liquid water clouds could not patterns in a few sections of the country can form except at supersaturations of several be ascribed to the inadvertent seeding of hundred percent. However, the sort of parti- clouds by industrial contaminants. cles required (called condensation nuclei) are Finally, tentative as our current informa- provided in overabundance by natural proc- tion and understanding may be, the long- esses. Only to the extent that higher-than- range potential effect of adding more and normal nuclei concentrations can affect the more particles to the atmosphere cannot be cloud-forming process, does man's introduc- ignored. As more is learned about the general tion of additional particulate material into circulation of the atmosphere and the deli- the atmosphere produce changes in observed cate balance betireen incoming and outgoing cloud structure and occurrence. radiation (the "throttle on the atmospheric The kinds of particles which cause precipi- engine"), it seems increasingly possible that tation from clouds, in contrast to those neces- small changes such as those occasioned by in- sary for cloud formation, are frequently in creasing particle loads in the atmosphere short supply in the atmosphere. In warm may produce very long-term meteorological (above freezing) clouds, the requirement is effects. a wide distribution of condensation nuclei, some .of which are giant hygroscopic nuclei B.EFFECTS OF PARTICULATE MATTER larger than 1/L. These "giants" promote the IN THE ATMOSPHERE ON VISIBLE rapid growth of cloud droplets by producing RADIATION some droplets large enough to fall with re- Stable particles of negligible fall velocity spect to the others. These grow rapidly by are probably the most common and persistent sweeping up smaller drops and very soon be- air pollutants. Their optical effects in produc-

35 9/27/61 AO 10/10/61 10/ 6/61 W E. 300 X 10/12/61 12/10/10/61 6/61 100 0 2 3 6 7 4 5 FIGURE 2-1. Relation of Solar Transmissivity to Height Above Ground in "Polluted" and "Clean" Areas. (This figure illustrates the effect of the attenuation of solar radiation reaching the ground.) e ) TRANSMISSIVITY (1/10) pollution on ing haziness, atmospheric turbidity, and a VISIBLE RADIATION reduction of visibility which hampers the LONDON/KEW safe operation of aircraft and motor vehicles, are well known. (See Chapter 3.) The solar JAN. radiation transmissivity /1o[A] where FEB. MAR. M. IN is the intensity of the normal-incidence solar radiation and Io [A] is the extra-terres- APR. trial value at this wavelength) varies with height and is strongly influenced by the dust MAY loading in the lower atmosphere.' Figure 2-1 JUNE illustrates the relation. of transmissivity at JULY A =5000 A to height in the atmosphere above AUG. an urban area under varying conditions of SEPT. particulate loading. In the case of heavily polluted air, thii radiation may be reduced by OCT. more than one-half in the lowest 300 meters NOV. of the atmosphere. There is also an increased DOC. attenuation of visible radiation near the JAN. I4 ground in clean airbut,the amount is small UI b PARTICULATE LOADING by comparison (Figure 2-1). AT KEW, mg/m3 It is well known that the reduction or attenuation of visible radiation in industrial- FIGURE 2-2. Annual Variation of the Ratio of Visi- ized urban areas, and the attendant gloom ble Radiation Levels in Central London and at caused by excessive concentrations of sus- Kew (), and of Concentration of Particulate pended particles in the air, create a need Matter at Kew (o) '(This figure indicates the for additional artificial illumination in of- relative attenuation of light at two sites in a large fices, factories, and homes, and produces city.) added economic stresses. This is particularly true in winter, when the days are shorter tensity of the direct sunlight so much that and the particulate content of the urban one can look directly at the sun without eye air is greater because of greater combustion strain or injury.In other words, haze in of fuels. Data given by *Shepherd I illustrate the atmosphere due to suspended particles some relationship, shown in Figure 2-2, be- scatters the light from the sun, making it tween particle concentrations and relative appear dim. visible radiation levels in London during Scattering of the sunlight by the particles summer and winter months. Daylight illumi- makes the air seem "turbid," and an optical nation was measured at two sites, one in cen- device called the Volz sun photometer has tral London, the other in Kew Observatory, a `been devised to measure this "turbidity" slightly less heavily polluted area 13 miles quantitatively .4 Starting with equations 3-2 WSW of the first site. As another example, in Chapter 3 (Lambert's Law), one calcu- the average loss of sunlight in the city of lates from the readings of this instrument Leningrad compared to the countryside was a "turbidity coefficient," B, related to the estimated to be 40 percent over the period of extinction coefficient b in equation 3-2, Chap- a 'year; in winter the loss was estimated to ter 3, or more specifically to b..t defined reach 70 percent in the city, while in summer there. The relationship between B and b the loss was about 10 percent.' is outlined by McCormick and Baulch, who Haze in the atmosphere due to forest fires, found that in a city B, the value of B meas- dust storms, or smoke from other sources, ured by the Volz instrument at a height of may become so concentrated at times that z meters above the ground, is related to B0, the sun appears red in the sky despite the the .value of B measured near ground level, absence of clouds. Just after sunrise or just by the equation before sunset, the haze may reduce the in- B.= BA-0.00346z (2-1).

37 From scattering theory, McCormick and ter vapor and ozone is negligible in the visible Baulch estimate that at any height, z, up to wavelength region usually studied.6. 7' 11 200 meters above the ground, the number of The scattering of light by aerosol particles particles per cubic meter, n' (z), in the rain ambient air is a complicatedprocess. Fart dius range between 0.714 and 114 is given by of the incident light is transmitted, part is n' (z ) =17.3 x 10°B.e-0.003460 (2_2) reflected in all directions either at the front Both of these equations are rough approxi- surface of the particle or at an internal dis- mations for light-wind, clear-sky conditions continuity, and part is absorbed. The trans- in a city during moderate to heavy pollu- mission factor for scattering isa function tion situations.In terms of mass loading of the wavelength of the incident light and near the ground, [m' (o)], the physical qualities of the scatteringme- dium. In simple cases where the form, size, rre(o)103130 (itgm-3) (2-3) and composition of !the scattering particles are known, the factor can be derived on a C.EFFECTS OF PARTICULATE MATTER theoretical basis and is known as "Mie" scat- IN THE ATMOSPHERE ON TOTAL tering. Chapter 3 provides a more extended SOLAR RADIATION discussion. . Landsberg 5 reports that cities in general Diffuse radiation is an important factor receive 15 percent to 20 percent less insola- in the amount of heat and light received at tion (on a horizontal surface) than do their any given location.3.1° The intensity and rural environs.Insolation, as used here, spectral distribution of direct sunlight and means the total solar radiation received at scattered daylight, and the varation of in- the earth's surface per unit area per unit tensity with time of diy, season, latitude, time. This discussion considers the part that altitude, and atmospheric conditions suchas airborne particles take in the diminution of turbidity, are important because they affect insolation received by cities. photosynthesis in plants and the distribution of plants and animals on earth, the 1.Physical Factors weathering of natural and man-madema- terials, climate, and illumination for human The attenuation of solar radiation through activity.° The percentage of direct solarra- the atmosphere is caused by a number of diation which will remain after its attenua- physical factors: 2.0-10 tion by smoke and other atmosphericcon- 1. Scattering of radiation, known as tituents depends both on the atmospheric Rayleigh scattering, by the air mole- tu bidity caused by the smoke, and on the cules, such as N2 and 0,, and par- altitudeof the sun above the horizon, as well ticles in size ranges less than the as on the Other Jactorsi° previously noted. wavelength of the solar radiation Except in casetof heavy particulate pollu- (the scattering coefficient is inversely tion of the atmospheie,.such as may occur Iroportional to the fourth power of in large urban centers Or heavy industry the wavelength of the incident ra- areas, it appears that the effect of turbidity diation; hence the short wavelength is to scatter radiation out of the direct solar radiation is scattered most, so that beam and to add an almost equal amount of the sky appears to be blue) radiation to the diffuse beam arriving from 2. Selective absorption by the gaseous the rest of the sky by forward-scattering. constituents of the atmosphere such In cases of heavy particle concentrations, as ozone and C0, and by water va- however, the loss from the direct solar beam por; and greatly exceeds the gain in the downward scattered beam, the difference being hist, to 3. Scattering and absorption by atmos- back-scattering off the top of the pollution pheric dusts and particulate matter layer and to absorption within the polluted of size greater than in (a). layer or column. The attenuation of solar radiation bywa- Studies indicate a fair approximation of 88 the association between atmospheric aerosol 3. the size distribution of the particles; concentration and relative solar radiation 4. relative humidity, which, in the case levels, as shown in Table 2-1. of hygroscopic aerosols, may alter the effective absorptivity and reflec- Table 2-1.APPROXIMATE ASSOCIATION BE. tivity of the particles; and TWEEN ATMOSPHERIC AEROSOL CONCEN- TRATIONS AND RELATIVE SOLAR RADIA- 5. temperature of the air and ground TION LEVELS. (on which the intensity of the terrestrial radiation depends). Solar radiation, percent of Aerosol concentration, value for 100p18 m-3 2.Seasonal Variations pg m-3 Total Ultraviolet The concentration of suspended particulate matter which ranges from less than 60 50 105 104 pg/m3 to 1700 pg/m3 in various American 100 100 100 cities shows a notable annual variation. 200 95 92 400 90 '7'7 Autumn and winter particulate levels are in- variably highest, and summer levels lowest. The weakening of radiation caused by smoke The reduction in ultraviolet light reaching is less during the summer when the sun is the surface may be as important as the at- high than in the winter.This would be tenuation of other, longer wave, components true even if there were the same degree of of solar radiation. Available data are sparse pollution in the air. The losses in intensity but one study 12 indicates that ultraviolet in- of direct total solar radiation during its pas- tensity decreased by about 7.5 percent for sage through an atmosphere polluted by each 100 pg/m-3 increase in aerosol con smoke may become as high as one-third in tent of the atmosphere with an average de- the summer and two-thirds in the winter.' ficiency of over 20 percent in the city as com- Landsberg has summarized the radiation pared with its environs in winter. Some loss data compiled by Steinhauser 13 for three studies suggest that a 5 percent reduction Central European citiesFrankfurt, Leip- in total solar radiation resulting from smoke zig, Viennaand their adjacent rural areas; almost completely eliminates the ultraviolet for the four seasons of the year. There are component.3.12Even ina comparatively contrasts in loss of solar radiation between clean atmosphere, the effective' ultraviolet spring or summer and Winter, as will be drops to very low values when the sun's elevation is below 30 degrees.'' seen in Tabr2-2. Steinhauser and co- workers 13 also reported that Vienna, receives The net influence of atmospheric turbidity a lesser total radiation than the nearby coun- on surface temperature is uncertain, but for tryside:in winter 85 percent of the total typical turbidity indices in the United States, solar radiation of suburban Hoche Warte, it is likely to be small. The effect on solar in spring 92 percent, in summer 92 percent, radiation (warming in the upper region of and in autumn 87 percent. ". 13 The' absorp- the pollution layer due to extinction by the tion is strongest in the short (ultraviolet) upper region) tends to be compensated by wavelengths.", ". 13' 14 the effect on radiation returning to space This annual cycle is observed to be a func- from the earth's surface and atmosphere. tion of latitude, dependent on the changing The extent to which the solar radiation effect midday sun angle. The scattered radiation prevails over the terrestrial radiation effect, during the summer months (May-August) or vice versa, is dependent on a number of may amount to approximately 60 percent to factors which include: . 65 percent of the direct radiation at 60° lati- A 1. the time of day and year (on which tude and to about 45 percent at 40° latitude. the intensity of solar radiation is itself dependent) ; 3.Weekly Variations 2. the total mass and vertical distribu- In addition to the seasonal and diurnal tion of the particles; variations or patterns of total solar radia- 51 39 tion in urban communities, a weekly cycle showed the marked diminution in dust and of intensity of total solar radiation has been smoke levels resulting from the falling off observed,22-22 which is related to the weekly in the amount of manufacturing during this cycle of industrial and commercial activity. period. In general, the total solar radiation received is inversely related to the concentration of D. INFLUENCE ON PRECIPITATION smoke and suspended particles; thus solar radiation measurements may be used, in the There is evidence that some of the parti- absence of clouds, as a crude index of par- cles introduced into the atmosphere by man's ticulate air pollution. activities can act as nuclei in processes which affect the formation of clouds and precipi- Table 2-2.LOSS OF SUN'S RADIATION IN tation. THREE EUROPEAN CITIES OVER THAT IN Condensation nuclei inthe size range THE ADJACENT COUNTRY.' greater than 11& are often made up of hygro- Solar Elevation scopic particles. 2° Because of their affinity for water, these particles play an important role in the transformation and condensation Season 10° 20° 30° 45° . of water vapor into liquid water droplets or PercentPercentPercentPercent solid ice particles, and are of vital impor- Winter 36 26 21 tance in the formation of fog, clouds, and Spring 29 20 15 11 rain. Combustion products of man's indus- Summer 29 21 18 14 try and technology, as well as volcanic erup- Autumn 34 23 19. 16 tions and ocean sprayf are significant sources r of these nuclei. A parallelism exists between Mat:eer " studied the total solar and sky the concentration of dust and that of conden- radiation patterns in metropolitan Toronto sation nuclei in city air. (See Table 2-3.) from October 1937 to 1960 and compared the radiation received on Sundays to the aver- Table 2-3.MEAN NUMBER OF CONDENSATION age of the weekday radiation readings at NUCLEI FOR VARIOUS RANGES OF DUST the same central site. The average radiation CONCENTRATIONS IN CITY AIR."' on Sundays for this period was 313.8 lang- Number of Mean number of leys (1 langley= 1 g cal/cm2) while the dust particles condensation nuclei mean per cm' per cm' for the weekday radiation was 305.2 lang- <500 189,000 leys, a difference of 8.6 langleysor 2.8 per- 500-999 211,000 cent. The probability of obtaining sucha >999 223,000 difference by chance was less than 0.5per- cent. Thus, while a real difference in radia- A pronounced parallelism can also be tion exists between Sundays and weekdays, found with respect to diurnal and annual the magnitude is rather small. variations in the contents of atmospheric dust and nuclei."12-22The excess production 4.Other Variations of condensation nuclei in the air over cities Hand 18 has noted that the average daily is a long established fact,'.20, 23and has been solar,radiation in various cities was signifi- reaffirmed with many amplifying circum- cantly higher over the entire year 1932 than stances."23 Evidence has been presented over the prior year. The largest increase in that giant nuclei, which may initiate thecoa- solar radiation was found to be in New York lescence process, are more abundant in in- City ( +21.9 percent), while Pittsburgh and dustrial areas than elsewhere." Washington showed yearly increases of 6.2 The diurnal, weekly, and yearly cycles of percent and 8 percent respectively. The busi- both suspended and dustfall particleconcen- ness depression was probably a major factor trations, correspond closely to man's pattern in this increase.Records for New York, of activities and combustion requirements. Chicago, and Pittsburgh for theyear 1932 There are usually two diurnal peaks (see 40 Figure 2-8), greater midweek concentrations jacent countryside and the variations of par- compared to Sundays, and greater mean con- ticle concentrations in the atmosphere.22-24 centrations in winter than in summer (see The influence of cities on precipitation is Figure 2-4)." complex; however, there is a general tend- A correlation has been found between pat- ency for urban factors to increase precipita- terns of precipitation over cities and the ad- tion." These factors, not necessarily in order of importance, are: 1. water vapor addition from combustion sources and processes; a! INIFFItIENT SMOKE' FROM NEIGHBORING OMBUSTION DISTRICTS 2. thermal updrafts from local heating; FFECT SMOKE 3. updrafts from increased friction tur- CONCENTRATION bulence; 4. added condensation nuclei leading to S more ready cloud formation; and, ::1I° 4, EFFECT OF 5. added nuclei which may act as freez- Ve TURBULENCE ing nuclei for super-cooled cloud particles. ,,,;;;,,Y% COAL CONSUMPTION' "4444; Landsberg 23 cites as evidence the gradual 0 1 L I A increase .o '2 4 6 810 12 14 16 18 20 22 24 ofrainfall which followed the CLOCK TIME growth of Tulsa, Oklahoma, from a village to a city in five decades and the concomitant FIGURE2-3. Causes of Cyclical Diurnal Smoke Vari- increase in particle concentrations. A study ations.° (This figure shows causes of changes in by Kline and Brier25in metropolitan Wash- the diurnal airborne particulate concentration in an urban location.) ington, D.C., indicates that there is a considerably higher level of freezing nuclei in the metropolitan area than there is in the adjacent countryside. Ashworth24first suggested the correlation between the weekly cycle of smoke in industrial areas and that of precipitation. Fred- erick," in a more recent analysis, showed a definite minimum Sunday rainfall for a ten- year period in Louisville, Pittsburgh, and Buffalo.". 28Precipitation occurred in these less often on Sundays than on other days of the week, and the average rainfall was less forSundays than for weekdays. A strong city influence is also suggested in the snow patterns in Toronto.27 An interesting and significant increase in precipitation has been observed at La Porte,

ci >- Indiana, since 1925. La Porte is 30 miles W U,1 U W u. a§ z zato 0 2 0 east of the largecomplex of heavy indus- triesinthe metropolitan Chicago area. Changnon 28 compared precipitation at La FIGURE2-4. Yearly Cycle (Averaged Over Six Porte, Valparaiso, and South Bend, Indiana, Years) of Deposited Pollutants. (This figure illus- with a five-year moving average of the num- trates the variation of amount of pollutants deposited at Leicester town hall averaged over the ber of smoky and hazy days in Chicago (Fig- six years ending March 1939, and shows the ure 2-5). The temporal distribution of the greater mean concentration in winter as compared smoke-haze days after 1980 is rather similar with summer.) to the La Porte curve. A notable increase in it 41 smoke-haze days began in 1935,becoming He found that smoke from steel furnaceswas more marked after 1940, coincident with the a prolific source of freezing nuclei, increas- sharp increase in the La Porteprecipitation ing counts by a factor of 50over those in curve. The reduction in the frequency of nearby clean air. He concluded that there smoke-haze days after the peak reachedin should be increased rainfall downwind of 1947 also generally matches thedecline of such installations. the La Porte curve since 1947.28 Stout " has shown that the shape of the E.RELATION TO WORLDWIDE time - series curve for. La Porte precipitation CLIMATIC CHANGE also generally matcheda time-series curve Theoretical considerations and empirical for annual steel production in theChicago evidence indicate that atmospheric turbidity, industrial complex. Between 1905 and1965, itself a function of aerosol concentration,is peaks in steel production, which occurred an important factor in the heat balance of when production in most other industries the earth-atmosphere system. Theobserved was also high, were all associated with high increase in turbidity over the past few points in the La. Porte precipitation dec- curve. ades may play a role in the reporteddecrease The effect of industrial pollutionon pre- in worldwide air temperature since1940 by cipitation has also been studied by Telford." increasing the planetary albedo.7. al 300

CHICAGO SMOKE HAZE LA PORTE, DAYS 270 0 1800 -,0 6

I- < N 240 1400 x 0 z

0 2 (I) 210 1 000 OBSERVER CHANGES AT LA PORTE 0LL i so 600 2

SOUTH BEND 150 200 . / " .00 1 1 1 0 1910 1920 1930 1940 1950 1950 ENDING YEAR OF 5-YEAR MOVING AVERAGE FIOURE2-6. Precipitation Values at Selected Indiana Stations and SmokeHaze Days at Chicago.(This figure shows the way in which precipitation trendsat La Porte follow the haze changes in Chicago. plotted as five-year moving averages.) The results are

42 Angstrom estimated roughly that a change the increased population and urbanization of in the albedo from 0.40 to 0.41 corresponds the District since the turn of the century. to a change in the mean temperature of the A significant remainder, however, as judged earth-atmospheric system of close to 1° C." by the Davos increase, may be indicative of Humphreys 33 made similar calculations with a much more general buildup of atmospheric roughly the same results, and also showed aerosol. that the interception of outgoing radiation When the above facts are put together, by fine atmospheric dusts is wholly negligible they indicate that for Washington, D.C., dur- in comparison with the interception of in- ing the period 1903 to 1966, there has been coming solar radiation. .Temporal and spa- a possible decrease of nearly 3 percent in tial changes in the atmospheric turbidity of the total available solar energy at ground 100 percent, corresponding to albedo changes level and a possible increase in the average of 10 percent to 15.percent, from one day annualnumber ofaerosolparticlesof to the next or from one locality to another, 2.8 x 107cm2. The net effect of this apparent are very commonplace." Even though these secular increase in turbidity (which from figures may well overestimate the actual the Davos, Switzerland, and other evidence" changes brought about in atmospheric tem- appears likely to be worldwide) is probably peratures, the course of atmospheric turbid- to increase the mean albedo of the planet ity over the earth is an important climatic and reduce the mean temperature of the factor. earth-atmosphere system. There are data available 3'. " from which The increaseinatmospheric turbidity the trend in turbidity during the past cen- consequent upon volcanic eruptions may tury can be estimated. Angstrom gave 0.098 have temporary effects on atmospheric tem- as the value of the mean annual turbidity at peratures.Mitchell 3"concluded that tem- Washington, D.C.(1903 to1907) ," and peratures over large areas of the world may 0.024 as the value at the Davos Observatory, be depressed by 0.5° F or more in the first Switzerland (1914' to 1926). The values for or second year following an unusually violent Washington Were determined from data on eruption.However, McCormick and Lud- solar transmission (by wavelength) pub-wig 3' suggest that the effects of man's pol- lished by the Smithsonian Institution; those lution of his environment are increasing for Davos were from data attributed to Lind- steadily along with the world population. holm on dust absorption.In 1962, deter- The emission of long-lived particles, keeping minations of the atmospheric turbidity were pace with the accelerated worldwide produc- begun at the Continuous Air Monitoring tion of CO.,, may well be leading to the de- Program station 31' 33 of the. Public Health crease in world air temperature in spite of Service, near the Smithsonian Institution; the apparent buildup of CO:.'" the mean annual turbidity, recorded for 1962 to 1966 was 0.154,33 a 57 percent increase F.SUMMARY over the 1.903 to 1907 values. From 1957 Atmospheric particles scatter and absorb to 1959, determinations of atmospheric tur- light from the sun, thus reducing the visible bidity were again made for Davos by Valko 33 radiation available to cities and the solar and were given as 0.043, a 70 percent in- radiation that reaches the earth. The gloom crease. due to reduced illumination in urban areas When the scattering theory with a Junge creates a need for artificial lighting in offices, distribution of particle size* is used, the factories, and homes and produces related values of turbidity change imply an increase economic stresses. The average year-round in the average annual number of aerosol par- illumination(i.e., the portion of the spec- ticles, in the range of 0.1.A to 1A radius, of trum that is visible to the eye) may be re- 2.8 x 107cm2 and 0.95 X 107/cm2 over Wash- duced by one-third or more in some cities. ington and Davos respectively, during the Daylight illumination in the center of Lon- periods shown. Nearly two-thirds of the don, for example, was found to be 20 per- Washington increase might be attributed to cent less than that found at a slightly less-

48 polluted part of the city quite near the center. in the delicate heat balance of the earth- Part of the sunlight reaching the earth atmosphere system, thus altering worldwide comes from the direct beam and part from climatic conditions. The rise in atmospheric that scattered from the rest of the sky. The turbidity increases the planetary reflectivity, total solar energy reaching the earth is the or albedo, and reduces the solar energy avail- sum of both the direct and the scattered ra- able to maintain surface temperatures. This diation.In general, cities receive 15 per- phenomenon may be responsible for the recent to 20 percent less total solar radiation ported decrease in worldwide temperature than do rural environments, although the net since the 1940's. Comparisons at different reduction may be considerably greater under sites over the world covering periods as long some circumstances.For a typical urban as fifty years suggest that a general world- area in the United States, with a geometric wide rise in turbidity may be taking place. mean annual concentration of roughly 100 This may well be indicative of a gradual pg/m3, the total sunlight is reduced approxi- buildup of worldwide background levels of mately 5 percent for every doubling of par- suspended particulates. The increasing lev- ticle concentration. This effect is more pro- els of atmospheric carbon dioxide resulting nounced on the ultraviolet portions of the from man's combustion of fuels probably spectrum. exerts an opposite effect on worldwide tem- Diurnal, weekly, and yearly cycles of both peratures, but the emission of long-lived par- suspended particulates and dustfall particles ticles to the air may gradually depress world correspond closely to man's pattern of activi- air temperature despite the. apparent build- ties and his combustion requirements. There up of carbon dioxide. are usually two daily peaks, greater midweek Some of the particles introduced into the concentrations compared with Sundays, and atmosphere by man's activities also can af- greater mean concentrations in autumn and fect the weather by serving as condensation winter than in spring and summer. The sea- nuclei that influence the formation of clouds, sonal variations are due largely to the use rain, and snow. The large airborne particles of coal and heavy fuel oil for heating pur- generated in metropolitan areas serve as a poses. Solar radiation attenuation patterns base for the condensation of moisture and also show weekly and seasonal variations. _lead to the rapid formation of rain droplets On weekdays, the attenuation isslightly or ice crystals.Patterns of precipitation more than on Sundays, and the losses in in- over cities and the adjacent countryside have tensity of the direct beam during its passage shown a correlation with particle concentra- through an atmosphere polluted by smoke tions in the atmosphere. Some cities display may become as high as one-third in the sum- a definite minimum rainfall on Sundays, mer and two-thirds in the winter. Even vari- when particulate levels are usually lowest, ations from year to year have been noted; and records over several decades reveal that for example, levels of total solar radiation rainfall levels may increase with the con- measured in various cities were significantly comitant rise in particulate levels that gen- higher in 1932 than in the prior year, un- erally accompanies urban growth. In addi- doubtedly because of the decline in manu- tion, long-term changes in the frequency of facturing and industrial activity brought smoke-haze days in one city may affect rain- about by the depression. Reductions in the fall levels in a nearby downwind city. intensity. of solar radiation or changes in its Thus airborne particles can, through a spectral distribution have significance for number of mechanisms, influence man's sur- the photosynthesis of vegetation, the distri- roundings, and have considerable impact on bution of plants and animals on the earth, weather and climatic conditions. the weathering of natural and manmade materials, and man's aesthetic enjoyment and G.REFERENCES It physical well-being. 1. Sheppard, P. A. "The Effect of Pollution on The increased emission of fine particles Radiation in the Atmosphere." Intern. J. Air into the atmosphere also may cause changes Pollution, Vol. 1, pp. 81-43, 1958. 44 2. McCormick, R. A. and Baulch, D. M. "The Vari- 17. Mateer, C. L. "Note on the Effect of the Weekly ation with Height of the Dust Loading over a Cycle of Air Pollution on Solar Radiation at City as Determined from the Atmospheric Tur- Toronto." Intern. J. Air Water Pollution, Vol. bidity." J. Air Pollution Control Assoc., Vol. 12, 4, pp. 52-54, 1961. pp. 492-496, 1962. 18. Hand, I.F."SolarRadiation Measurements 3. Sheleikhovskii,G.V."Smoke Pollutionof During December 1932." Monthly Weather Rev., Towns." Akademiya Kammunal'nogo Khzyaistva Vol. 60, pp. 256-257, 1932. im. K. D. Pamfilova. [Academy of Municipal 19. Neuberger, II. "Condensation Nuclei: Their Sig- Economy im. K. D. Pamfilova.] Izdatel'stvo Min- nificance in Atmospheric Pollution." Mech. Eng., isterstva Kommunal'nogo Khozyaistva RSFSR, Vol. 70, pp. 221-225, 1948. Moskva-Leningrad. 1949. (Translatedfrom 20. Landsberg, H. "Atmospheric Condensation Nu- Russian and published for the National Science clei." Erg. Kosm. Physik., Vol. 3, pp. 155-252, Foundation, Washington,.D.C. by the Israel Pro- 1938. gramforScientifictranslations,Jerusalem, 21. Giner, R. and Hess, V. F. "Studie uber die Ver- 1961.) teilung der Aerosole in der Luft von Innsbruk 4. Volz, F."Photometer mit Selen-Photoelement und Umgebung." Gerlands Beitr. Geophys., Vol. zur spektralen Messung der Sonnenstrahlung 50, pp. 22-43, 1937. und zur Bestimmung der Wellenlangenabhangig- XT. Georgii, H. W. "Probleme und Stand der Erfor- keit der Dunsttrubung." Arch. Meterol. Geophys. schung des Atmospharischen Aerosols."Ber. Bioklimatol., Ser. B, Vol. 10, pp 100-131, 1959. Deutsche Wetterdienste., Vol. 7, pp. 44-52, 1959. 5. Landsberg, H. "Physical Climatology." 2nd edi- 23. Landsberg, H."City AirBetter or Worse." tion, Gray, DuBois, Pennsylvania, 1958, pp. 317 - In: Air Over Cities Symposium, U.S. Dept. of 326. Health, Education, and Welfare, Robert A. Taft 6. Angstrom, A. K. "On the Atmospheric Trans- Sanitary Engineering Center, Cincinnati, Ohio, mission of Sun Radiation II." Geograph. Ann. Technical Report A62-5, 1962, pp. 1-22. (Stockholm), Vol. 12, pp. 139-159, 1930. 24. Ashworth, J. R. "The Inil.ence of Smoke and 7. McCormick, . R. A."Atmospheric Turbidity." Hot Gases from Factory Chimneys on Rainfall." Preprint.(Presented at the 60th Annual Meet- Quart. J. Roy. Meteorol. Soc., Vol. 55, pp. 341- ing, Air Pollution Control Association, Cleve- 350, 1929. land, Ohio, June 11-16, 1967.) 25. Kline, D. B. and Brier, G. W. "Some Experi- 8. Stagg, J. M. "Solar Radiation of Kew Observa- ences on the Measurement of Natural Ice Nu- tory." Air Ministry, Meteorological Office, Lon- clei." Monthly Weather Rev., Vol. 89, pp. 263- don, Geophysical Memoirs 86, 1950. 272, 1961. 9. Gates, D. M. "Spectral Distribution of Solar 26. Frederick, R. H. Personal communication. U.S. Radiation at the Earth's Surface." Science, Vol. Weather Bureau. 151, pp. 523-529, 1966. 27. Potter, J. G. "Chan.ges in Seasonal Snowfall in 10. Robinson, N. "Solar Radiation." Elsevier, Am- Cities." Canadian Geographer, Vol. 5, pp. 37-42, sterdam, London and New York, 1966. 1961. 11. Angstrom, A. K. "On the Atmospheric Trans- 28. Changnon, S. A. Jr."The La Porte Weather mission of Sun Radiation and Dust in the Air." Anomaly, Fact or Fiction." Bull. Am. Meteorol. Geograph. Ann. (Stockholm), Vol. 11, pp. 156- Soc., Vol. 49, pp. 4-11, 1968. 166, 1929. 29. Stout, G. E. "Some Observations of Cloud Ini- 12. Shrader, J. H., Coblentz, M. H., and Korff, F. A. tiation in Industrial Areas." In: Air Over Cities "Effect of Atmospheric Pollution upon Incidence Symposium, U.S. Dept. of Health, Education, of SolarUltravioletLight." Am. J.Public and Welfare, Robert A. Taft Sanitary Engineer- Health, Vol. 19, pp. 717-724, 1929. ing Center, Cincinnati, Ohio, Technical Report 13. Steinhauser, F., Eckel, 0., and Sauberer, F. A62-5, 1962, pp. 147-153. "Klima und Bioklima von Wien." Wetter und 30. Telford, J. W. "Freezing Nuclei from Industrial Leben, Vol. 7, 1955, 120 pp. Processes." J. Meteorol., Vol. 17, pp. 676-679, 14. Kenrick, G. W. and Ortiz, H. "Measurements 1960. of Ultra-Violet Solar Radiation in Puerto Rico." 31. McCormick, R. A. and Ludwig, J. H. "Climate Trans. Am. Geophy. Union, 19th, 1938, pp. 138- Modification by Atmospheric Aerosols." Science, 140. Vol. 156, pp. 1358-1359, 1967. 15. Meetham, 'A.R."Atmospheric Pollutionin 32. Angstrom, A. K. "Atmospheric Turbidity, Glo- Leicester. A Scientific Survey." Dept. of Scien- bal Illuminators and Planetary Albedo of the tific and Industrial Research, London, Atmos- Earth." Tellus, Vol. 14, pp. 435-450, 1962. pheric Pollution Research Technical Paper 1, 33. Humphreys, W. J."Volcanic Dust and Other 1945. Factors in the Production of Climatic Changes 16. Meetham, A. R."Atmospheric Pollution:Its and their Possible Relation to Ice Ages." Bull. Origin and Prevention." Pergamon Press, New Mount. Weather Observatory, Vol. 6, pp. 1-34, York, 1961. 4 1914. ( 57 45 It

34. Peterson, J. T. and Bryson, R. A. "Atmospheric Meteorol. Geophys. Bioldimatol., Ser. B, Vol. 11, Aerosols: Increased Concentrations During the pp. 143-210, 1961. Last Decade."Science, Vol. 162, pp. 120-121, 37. Mitchell, J. M., Jr. "Recent Secular Changes in 1968. Global Temperatures."Ann. N.Y. Acad. Sci., 35. "Atmospheric Turbidity Report." U.S. Dept. of Vol. 95, pp. 235-250,1961. Health, Education, and Welfare, National Cen- 38. "Restoring the Quality of Our Environment." ter for Air Pollution Control, Cincinnati, Ohio. Report of the Environmental Pollution Panel, (Quarterly) President's Science Advisory Committee, The 36. Valko, P."Untersuchung Uber die vertikale White House, Washington, D.C., November 1965, Triibungsschichtung der AtmosphUre."Arch. pp. 111-131.

.5S 46 Chapter 3

EFFECTS OF ATMOSPHERIC PARTICULATE MATTER ON VISIBILITY

u- Table of Contents Pogo A. INTRODUCTION 51 B. IMPORTANCE OF ATMOSPHERIC AEROSOLS TO THE GEN- ERAL OPTICAL PROBLEM 51 C. PHYSICAL RELATIONSHIPS BETWEEN VISIBILITY AND PAR- TICLE CONCENTRATION 52 D. COMPLICATIONS AND LIMITATIONS IN THE VISIBILITY PROBLEM 53 1. Smoke Plumes 53 2. Natural Aerosols and Hazes 53 3. Fogs 54 E. THE LOW-HUMIDITY, WELL-AGED HAZE 54 1. Size Distribution 54 2. Mie Solutions 54 3. Dependence of Extinction of Particle Size for the Atmospheric Case, 4. The Mass-Light Scattering Relationship 55 F. DETERMINATION OF WELL-DEFINED CASES OF MASS- VISIBILITY RELATIONSHIPS 58 G. METHODS FOR DETERMINING LIGHT SCATTERING COEFI- CIENT-MASS CONCENTRATION RELATIONSHIP 59 H. SUMMARY 60 I. REFERENCES 61 List of Figures Figure 3-1Four TypiCal Measured Size Distributions of Atmospheric Suspended Particles Together with the Corresponding Visibilities 54 3-2The Relation of Scattering Cross-Section to Particle Size for Parti- cles of Three Different Refractive Indices 55 3-3Cross Section Curve for Typical Atmospheric Size Distribution, . .... 55 3-4The Dependence of Scattering Coefficient (nr!) on Volume of Aero- sol Particles (1.0/cm3) Calculated from Measured Size Distributions 56 3-5Measured Dependence of Mass of Aerosol Particles per Volume (4/ m3) on the Light Scattering Coefficient (mr-I) in Seattle, November- December 196i3 56 3-6Histogram of Equivalent Visual Range-Mass Concentration Product at Several Locations 57 3-7Relation Between Visual Range and the Mass Concentration 57 3-8Three Horizontal Profiles through the City of Seattle Taken under Differing Meteorological Conditions 59

48 60 List of Tables Table Page 3-1Relation Between Equivalent Visual Range andParticle Concentra- tion 57 3-2 The Relative Humidity at which Phase ChangeOccurs in Some De- liquescent Aerosols 59

tws Chapter 3

EFFECTS OF ATMOSPHERIC PARTICULATE MATTERON VISIBILITY

A.INTRODUCTION trends of both increasing and decreasing One of the dramatic effects of air pollu- amounts of smoke or other atmospheric aero- tion is a degradation of the visibility. Visi- sol. Robinson 2 also discussed the use ofme- bility in the atmosphere is reduced by two teorologicalvisibilityrecordsandtheir optical effects which air molecules and aero- interpretation. Both Holzworth 1 and Robin- sol particles have upon visible radiation. One son = demonstrated that visibility degrada- is the attenuation by the molecules and par- tion can be associated with air pollution. ticles of the light, passing from object to ob- Neither, however, developed the sort ofcor- server. It is the result both of absorption relation between mass of suspended particu- of light and of the scattering of light out of late matter per volume of air and visibility the incident beam. The light received from that is needed for air quality criteria. Rob- the object and that received from its back- inson indicated doubt in the existence ofa ground are diminished by this attenuation, generallyapplicablerelationship between and the difference between the two (con- massconcentrationandvisibility.This trast) is consequently diminished with the doubt was based on experimental resultsas result that the eye's ability to distinguish the well as on the complexity of the problem. object from its background is reduced. The Recentexperimental and theoreticalad- other optical effect that degrades the contrast vances make possible some useful conchi- between object and background is the illumi- sions, and this chapter will definea simple nation of the intervening air which results relationship between .mass of suspendedpar- when sunlight is scattered into the line of tic/e9 and visibility,specify the circum- sight by the molecules and particles in the stances under which it can be expected to be line of sight.It is a common observation reliable, and describe the conditions which that darkobjects become progressively are too complex for this simple treatment. lighter in shade as they become more distant. In the United States, the words visibility The most distant mountain that one can dis- and visual range are usually usedsynony- tinguish typically is almost as lightor bright mously to mean the distance at which it is as its sky background. just possible to perceive an object against In those cases where a clear-cut relation- the horizon sky.Middleton 3 reports that ship can be shown to exist between visibility the originator of both terms intended that and the mass of suspended particlesper vol- only visual range be considered as a distance, ume of air (mass concentration), it is pos- while visibility should convey amore quali- sible to use some of the meteorological visi- tative judgment about the clearness ofsee- bility records t) infer the amount of pollu- ing. In this chapter, however, the terms visi- tion in past years as well as to study trends. bility and visual range will be used inter- In fact, many such studies have been made changeably to mean a distance. even without a substantive knowledge of the relationship. Holzworth 1 used existing visi- B.IMPORTANCE OF ATMOSPHERIC bility data both as an indication of the AEROSOLS TO THE GENERAL amount of pollution for comparison of an OPTICAL PROBLEM

,fs urban (Columbus, Ohio) area with a rural Decreased visibility obviously interferes area, and for the qualitative inference of with certain important human activities,

51 62' such as the safe operation of aircraft and crement of path dx. The relationship be- automobiles and the enjoyment of scenic tween intensity and distance is: vistas. The effect of decreased visibility on dI the large-scale operations of commercial air- = b dx (3-1) craft in metropolitan areas is a problem of I growing concern. The Federal Air Regula- or, in integrated form, tionsof 19674(paragraphs 91.105 and 91.107) prescribe limitations on aircraft op- I= Ioe-bx (3-2) eration that become increasingly severe as where b is the extinction coefficient assumed visibility decreases below five miles. Most re- to be constant over x, and I. represents the strictions are invoked when the visibility is intensity of light at x = 0. below three miles. In areas with a high den- The extinction coefficient, b, is the sum of sity of aircraft traffic, visibilities much below four terms: five miles tend to slow down operations by maintaining larger separations between air- 1. the scattering coefficient of the air molecules, b craft. Even though most commercial air- Rayleigh " planes always fly under Instrument Flight 2. the scattering coefficient of particles or Rules rather than Visual Flight Rules, good aerosol, b .visibility increases both the safety and per- scat 3. the light absorption by gases, b mitted traffic density. Light airplane opera- abs -gas' tions are limited even more severely when and, visibility is less than three miles, because of 4. the light absorption by the aerosol, b their limited 'instrument flight capability. abs-aerosol. A 1963 report by the Civil Aeronautics Of these four, the scattering due to aerosol Board to the Committee on Public Works, is usually assumed to dominate in haze.= The U.S. Senate,r states that records of both au- process of scattering amounts to the removal tomobile and aircraft accidents show cases of light from the original beam and its redis- where poor visibility due to smoke and air tribution in different directions. Scattering pollution was an important causal factor. thus differs from absorption in which the Evidence presented at Federal air pollution light energy is lost to the absorber; in scatter- abatement conferences 6'shows the existing, the light energy is only spatially redis- ence of air pollution that curtails visibility, tributed. Nonetheless, this removal of light endangering the safety of people traveling from the beam (or line of viewing) does re- by both land and air, and in addition, causing sult in extinction. It suffices to state only the inconvenience and economic loss to the pub- final result in equation 3-2 for the usual lic and to transportation companies due to assumption of 2% contrast threshold for an disruption of traffic schedules. "average" human eye.2.8 L =3.9 C.PHYSICAL RELATIONSHIPS v b BETWEEN VISIBILITY AND scat (3-3) PARTICLE CONCENTRATION Here, L, is the visual range in meters and b is, as before, the extinction coefficient per Many deriyations of visibility theory have meter along the path of sight for the case of been published. Although Robinson's 2 ap- a black object. If b is determined at a point proach is directed towards the air pollution without knowledge of the entire sight path, problem, Middleton's 3 book presents a more then L, is "equivalent visual range," i.e., the complete view of the problem of atmospheric distance one could see if the extinction coeffi- clarity. cient were constant along the sight path. A For the simplest case of attenuation of a discussion of the dependence of extinction light beam along its path, the intensity, I, coefficient on the amount of atmospheric decreases by an increment dI over the in- aerosol follows in Section F.

52 "Visual quality" as perceived by even the of the plume is pertinent to the eventual air well-trained observer is not so easily describ- composition, even though appearance may be ed. Among the complications is the fact that aesthetically objectionable. particles responsible for urban haze scatter Secondly, although many meteorological more light in a direction close to that of the mixing equations have been proposed, they original beam (so-called forward-scatter) cannot describe individual eddies of smoke as and less light in a backward direction. Thus, the plume disintegratesmThe equationswere the same haze may appear to be much more meant for describing averages and not an dense when looking toward the sun and less instantaneous property such as the extinction dense when looking away from the sun. of light in some particular eddy of smoke as Besides this directional factor, there is also determined by eye, perhaps with the aid of a a wavelength (or color) dependence. Ang- Ringelmann Chart. strom,9 Junge,9 and others have shown that Because of these probleMs, the topics of the extinction coefficient of hazes in general plumes and plume optics are discussed only is inversely proportional to a power of wave- briefly in this chapter, and the presentation length: is concerned primarily with the aerosolpro- b = 1 duced after the initial meteorological mixing Aa (3-4) of the plume has occurred. The reader is referred for further information on plumeop- where a has measured values of around 1.0 to tics to the study by Conner and Hodkinson." 1.5. This relation indicates that blue light (of The Ringelmann number may provide an shorter wavelengths) will be scattered to a objective measurement of public sentiment greater degree than red light(of longer regarding the disagreeable appearance of wavelengths). It is for this reason that thd smoke plumes, although aesthetic aspectsare sun's disc, when observed througha haze that difficult to quantify.-Robinson 2 shows the as- is dense enough to permit such viewing,ap- sumptions and size distribution information pears red, orange or even brown though light that are necessary for relating plume opacity absorption is not necessarily occurring. to the aerosol content of smoke. The difficulties inherent in visual evalua- D. COMPLICATIONS AND LIMITATIONS tion of smoke plumes do not eliminate the IN THE VISIBILITY PROBLEM possibility of using such observationsas an 1.Smoke Plumes aid in controlling air pollution. In principle, the Ringelmann Chart should be useful in Conner and Hodkinson," in tests on the estimating the obscuring of vision by plumes optical properties of well-controlled experi- and in setting limits to control the visibility mental smoke, found that visual effects are degradation downwind from a source ofpar not inherent properties of the plumes but ticulate matter. In practice, however, the vary with the background of the plume and problem is extremely complex and requires with illuminating and viewing conditions. extensive study to develop better techniques Variation was much greater with white for measuring the contribution of individual plumes than with black. Tests conducted with plumes to visibility problems. trained smoke inspectors showed that their evaluations of non-black smoke plumes were 2.Natural Aerosols and Hazes significantly influenced by these variations. The general problem of natural particu- At least two real difficulties exist in making --late matterfrom whateversourcemust any generalizations about visual aspects of be considered. The oceans produce salt parti- smoke plumes. First, it is not possible to de- cles, tiees produce terpenes thatmay result termine the mass emitted per unit time from inorganic particles,"forestfires make a smokestack solely, on the basis of visually smoke, and so on. Man has little hope of con- perceived light scatter or absorption. The trolling the quality of air that enters the mass per unit time emitted from the stack urban areas from uninhabited lands. None- and not the appearance or optical properties theless, these low-humidity aerosols some- s4 63 times cause dramatic reduction in the visual Z. 34 m i l e s has low w i n d weed- range. In order to properly evaluate the im- high pressure over area. Seattle portance of natural aerosols, the visibility 45 miles hue deep low pressure < wee southwest of erns Sunk of the air mass should be determined before ). 1 it enters a populated area. 67 mileemin showeis and cumulus N clouds tops now moo foe. z Suttee 3.Fogs z 1040 miles (omen) high pressure When the relative humidity exceeds 'ap- over wee. Washington seacoast proximately 70 percent, many types of parti- 0: 104 W cles exhibit deliquescent behavior and grow o. into fog droplets. Natural particles such as 8 sodium chloride from the sea as well as many 103

products of human activity can thus act as c.) condensation nuclei (Chapter 2). The property of deliquescence and the relative humid- o.< 102 ity at which rapid and large change in parti- 0LL cle size occurs are both very dependent on CC sot" 101 the chemical composition and original size 2 of the particles. As a result, unless the chem- z ical composition as a function of particle size I rIitt11_ I I II 'isLI is known for the aerosol, very little can be .01 0.1 1.0 said about the relationship between visibil- PARTICLE RADIUS.p ity in even "thin" fog and the amount of FIGURE3-1. Four Typical Measured Size Distribu- material present as pollutant." tions of Atmospheric Suspended Particles To- Because little deliquescence occurs below gether with the Corresponding Visibilities." (The 70 percent relative humidity, the relation- figure shows that aerosols in the lowest region of ships to be presented here will be limited to the atmosphere (the troposphere) tend always to the range of humidity from 0 percent to 70 have similar size distributions.) percent. In cases of higher humidity, it is possible to decrease the relative humidity of sible to relate the optical properties of the the air by heating it for optical evaluation haze to the amount or mass concentration of of the amount of particulate matter, as de- material present. This generalization may scribed by Charlson et al." This humidity not apply to freshly-formed smoke. Brief limitation has already been adopted in Cal- guidelines for determining when the size ifornia." distributionhas become sufficiently well- defined will be .given later. E. THE LOW-HUMIDITY, WELL-AGED 2. HAZE The Solutions As mentioned earlier, another important 1.Size Distribution assumption which is usually made is that, of Recent advances in both theory and .tech- the four extinction components, light scatter- nology have resulted in a simplification of ing by aerosols dominates. Current research the description of well-aged aerosols. Junge,9 indicates that this is probably a justifiable Friedlander," Whitby," and others 17 have assumption." Figure 3-2 shows typical scat- shown that aerosols in the lowest region of tering cross sections for green light as a the atmosphere (troposphere),whether over function of particle size for aerosol particles urban areas or not, tend to have similar size important in haze, computed via the theory distributions. Figure 3-1 shows several typi- of Gustav Mie." For some particle sizes, dif- cal size distributions to illustrate this fea- ferences in the scattering coefficient of a fac- ture. tor of three exist between the two refractive If it is assumed that this recurring size indices which 'span the realistic range for distribution exists in general, then it is pos- the atmospheric case. However, Pueschel and

54 0r

.0 aq

cc z

0 cc -110.7

cc O LL zi-

LL LL Q1 0 PARTICLE RADIUS, # tt O FIGURE 3-2. The Relation of Scattering Cross-Sec- z tion to Particle Size for Particles of Three Dif- rc ferent Refractive Indices." (The figure shows that t-8,0 the scattering cross-section of atmospheric par- o 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 ticks varies roughly as the cube of their radius PARTICLE RADIUS,(p) within the range 0.1i to 1.0g. The range of refractive indices, 1.33 to 1.6, for which the propor- FIGURE 3-3. Cross Section Curve for a Typical At- tionality holds includes most materials found in mospheric Size Distribution." (The figure shows atmospheric aerosols.) the particle size dependence of atmospheric extinction obtained by breaking down the data of Figures 3-1 and 3-2 into 0.01p,-radius intervals, No1119 conclude that the extinction coefficient to yield the extinction coefficient of each radius of aerosols in the troposphere is nearly inde- interval.) pendent of the refractive index of the particles if the size distribution is close to those extinction coefficient, due to scatter, b.t, is described in Figure 3-1. obtained.

3.Dependence of. Extinction on Particle 1. The Mass-Light Scattering Relationship Size for the Atmospheric Case It is also possible to calculate the volume If the data in Figures 3-1 and 3-2 are of particulate matter per unit volume of air broken down into narrow radius intervals (i.e., in cubic microns of aerosol per cubic (eg., 0.04),and a calculation performed to centimeter of air). The familiar quantity of yield the extinction coefficient for each ra- areosol mass concentration (a/m9) is pro- dius interval, the particle size dependence of portional to this volume ratio via the particle atmospheric extinction of green light is re- density. Figure 3-4 shows the calculated rela- vealed. Figure 3-3 shows the results for a tionship of aerosol volume (10/cm9) to scat- typical size distribution of spherical parti- tering coefficient per meter. (for green light cles having a refractive index of 1Z. [5500A] and for a refractive index of 1.6) In general, this procedure shows that a based on 82 individual measured size distri- narrow range of particle sizes, usually from butions. Sixteen of.these size distributions 0.1p to 1p radius controls the extinction coef- used in Figure 3-4 were measured in Seattle ficient and therefore the visibility: If the under varying meteorological conditions. The, values of the extinction coefficient for each remaining 16 were obtained in the Austrian radius interval are thin- mmuned, the total.Alps under conditions where, presumably,

55 1000 1000

SEATTLE, WASHINGTON .*f/A E 300 300

Z. % 100 0)100 M 0 0 I= 8 > 30 4C 30 0 Icc 8 0 KALKALPEN, AUSTRIA ice 10 00 10 0Z 0 c.) 0 0 3 03 cc I 11121211 I 21121211 I atoms, 4C 1.0 I1121121 a I 1 1.0 2111w1 2 mitatt 0.1 0.3 1.0 3 10 30 x10'4 0.1 0.3 1.0 3 10 30 x10-4 LIGHT SCATTERING COEFFICIENT bsctim LIGHT SCATTERING COEFFICIENT bscatim FIGURE 3-4. The Dependence of Scattering Coeffi- FIGURE3-5. Measured Dependence of Mass of Aero- cient(m-')on Volume ofAerosolParticles sol Particles per Volume (pg/m) on the Light (iNcne) Calculated from Measured Size Distri- Scattering Coefficient (m-1) in Seattle, November- butions." (The solid circles are based on Seattle, December 1966." Washington, data and the open circles on Kalkal- pen, Austria, data.) 3-5 plotted in a different fashion to illustrate their distribution." From equations 3-3 and only natural aerosol was present. The im- 3-5, the product of equivalent visual range plication of these calculations is that the and mass concentration (L, x cone) can be volume, and thus the mass concentration of obtained. well-aged aerosol, is approximately proportional to the light scattering coefficient for Since atmospheric aerosols originating naturally 3.9 or as the result of man's activity." L,= (3-3) It follows, therefore, that even though the bscat aerosol mass is distributed over perhaps two multiplying both sides of the uation by or three decades of size, and light scatter is concentration gives caused by particles of one narrow size range, 3.9 X cone a proportionality can exist between the num- L, X cone (3-3a) ber of particles scattering light and the total bacat mass concentration of particles. Constant The units on both sides of this equationare shape of the size distribution here implies mass per area (e.g., pg/m2). If we use the that for all radius intervals, the number of particular proportionality in equation 3-5, particles in an interval is proportional to the then: number in. the corresponding interval in a L. X conc=4.2 x 101 tig/m2= 1.2 g/m2.(3-6) reference size distribution. This product has a simple physical signifi- Figure 3-5 shows data obtained by an in- cance: it is the mass of material in a column tegrating nephelometer 13 for a wavelength of length L, and one square meter in cross of 5000. A confirming this calculated depend- section. In other words, it is the amount of ence. The relationship can be summarized as material per square meter between the ob- follows: . server and a point at the limit of visibility. mass (aims) ze 3 X 102 beat /m. (3-5) Each point of Figure 3-5 can be used.to form this number since each pair of values of mass Figure 3-6 shows data like those of Figure concentration and scattering' coefficient can

56 A. All 238 cases. 35, 100

30. *v, E 25. 3 5 20 0

15 10

11 0 MASS CONCENTRATION, icis / m3 rr FIGURE 3-7.Relation Between Visual Range and B. New York City, 62 cases. Mass Concentration." (This figure shows the in- cc10. verse proportionality between visual range and tu co -mass concentration described by equations 3-7 and 2 5, 3-8.)

0 C. San Jose, California, Equation 3-5 can also be rewritten to include 48 cases. these upper and lower limits: rtwa mass (tig/m2)= (3:::°) x102 b.t/m (3-8) 10.1 D. Seattle, Washington Area. 45 cases Data in essential agreement with this result 5. have also been obtained recently by visual 0 methods in Oakland, California." As the E. Seattle, Washington, high 10 volume air sampler date, data indicate that equation 3-8 is applicable 83 cases. in a wide variety of cases," and because these locations seem to include a wide variety ofair pollution character, it is anticipated 00 4 0.8 1.6k 2.4 3.2 that this generalization may be useful in Ly x MASS, grams / m2 many urban areas. The relationship is shown in Figure 3-7 and Table 3-1.22 However, ex- FIGURE 3-6. Histogram of Equivalent Visual Range- perimental verification of the mass-light ex- Mass Concentration Product at Several Loca- tinction relationship is desirable for each tions? (The figure shows the number of cases location in question. with a given range of values of the product of mass and equivalent visual range for data at vari- Table 3-1.-RELATION BETWEEN EQUIVALENT ous locations studied. This product represent's' the VISUAL RANGE AND PARTICLE CONCENTRA- mass required to determine the visibility in a col- TION:" ume one square meter in cross section along the light path.) ScatteringEquivalent Equivalent Mass coefficient visual visual be used to obtain a different proportionality concentra- due to aerosol, range, range, of the sort shown in equation 3-5. Figure 3-6 tion pg/ne bmt/m km miles consists of histograms showing the number of occurrences for different values of the 1021, 0.3X10" 120.0 75.00 quantity 1,, x cone found at various locations. 30 1.0X10" 40.0 26.00 Here, since the modal value is about 1.2 g/m2, one can write: 100***) 8.3X10" 12.0 7.50 3001°'' 10.0X10" 4.0 2.50 X (g/m2) (3-7) -NM 1000": 33.0X10" 1.2 0.75 to include virtually all cases.

57 The accuracy of equations 3-'1 and 3-8 that suggested by equation 3-7 is necessary depends on many factors and assumptions. for determining the visibility. In the atmos- This research area is an active one, and new phere. a large percentage of the mass of the data are constantly being acquired. Improve- particulate matter is outside the size class ments in the understanding of these phe- important for light scatter (see Figures 3-1 nomena and the accuracy of descriptions will and 3-3) and a somewhat higher mass per r. no doubt occur in the near future. However, unit area is needed to determine the visibility. these values are known to be accurate to well within one significant figure for the cases measured, and their utility for criterion pur- F.DETERMINATION OF WELL-DEFINED poses is therefore clear. CASES OF MASS-VISIBILITY RELATIONSHIPS Photochemical ly produced aerosols, as well as other organic aerosols, can be expected to .As discussed above, any generalization 'have similar visibility effects if their size about the visibility-particle(aerosol) con- distribution remains reasonably constant. centration relationship is dependent on a Since the physical processes governing size well-defined and nearly constant size distri- distribution are assumed to be largely in- bution. The following list summarizes the dependent of the chemical nature of the par - cases in which equatiori 3-8 applies: ticles," the size distribution should be similar 1. the relative humidity should be below to those shown in Figure 3-1. However, if 70 percent. (For a discussion of the such particles are volatile or metastable to relationship between visibility and oxidation as suggested by Goetz," the mass concentrations of sulfur dioxide at determination may be difficult. Although vis- variousrelative humidities, see a ibility degradation is evident in photochem- companion volume to this document; ical smog, experimentally determined size Air Quality Criteria' for Sulfur Ox- distribution data are needed. ides.) Absolute humidity is relatively It can be seen from Figure 3-5 that the unimportant since the interaction' of practical unit of light scattering coefficient water vapor and hygroscopic aero- for 5000 A wavelength is 10-4/m. The value sols depends mainly on relative hu- 1 x 10-4/m represents fairly clean air with a midity. In the case of 'a particularly particlemass concentration of about 30 hygroscopic aerosol, the '70 percent µg /m', while 10 x 10-4/m represents more figure may be unreliable. Table 3-2 polluted air (concentration about .300 lig/ shows a list of compounds and the m3). Of course, the reciprocal relationship approximate humidity at which they (equation 3-3) could be used in combination deliquesce. If such a substance is with equation 3-5. present as a large percentage of the total aerosol, even though the rest L. (km) x 102/conc (iig/m3).(3-9) of the following conditions may hold, (See also Figure 3-7 and Table 3-1.) How- theapplicabilityofequation 3-5 ever, reciprocal relationships are harder to might be open to doubt. visualize than are direct proportionalities, 2. the size distribution must be well- and the extinction coefficient due to scatter established and close to the recurring (or just scattering coefficient)itself can form discussed earlier. Little experi- serve as an index for particulate pollution. mental information is available on It is interesting to compare the results of the length of time required for vari- equation 3-7 with Robinson's 2 calculation of ous types of fumes to attain a reason- 0.34 g/m2 for an oil aerosol in which all par- ably well-defined size distribution by ticles have the same 0.6, diameter. Sinee this coagulation and sedimentation. Meas- estimate represents a case in which all the urement of this parameter is there- pirticles are involved in the light scattering, fore desirable before any generaliza- it is not surprising that a mass smaller than tions are made about visibility. The 58 Table 3-2.THE RELATIVE HUMIDITY AT WHICH PHASE CHANGE OCCURS IN SOME DELIQUES- CENT AEROSOLS." 9 Approximate 31 AUGUST 1967 percent relative E 8 humidity at 1000-1030 PDT Substance which phase FOGGY change occurs LOW WIND SPEED at 25°C z7

Sodium hydroxide 7 T.6 Calcium chloride 29 U. Sulfuric acid 35 O 5 Magnesium chloride 33 Sodium iodide 38 I 4 I V e,/ Magnesium nitrate 53 /v Sodium bromide 58 / 30 AUGUST 19671 / cai 1530 Potassium iodide 69 v,3 /64 1615 PDT Sodium nitrate 74 LOW WIND SPEED Sodium chloride 75 S 2//5 SEPTEMBER 196T Potassium bromide 80 1530-1630 PDT STRONG SOUTH WIND.... Potassium chloride 84 Barium chloride 90 .1...... 0 20 15 10 5 0 5 10 15 20 25 30 most important qualification appears N. S to be that the aerosol in question DISTANCE FROM UNIVERSITY HIGH BRIDGE, Km must not be freshly formed as in a smoke plume. Times of the order of FIGURE 3-8. Three Horizontal Profiles Through the one hour may be adequate for the City of Seattle Taken Under Differing Meteorolog- establishment of a well-defined size ical Conditions.° (The figure illustrates the pos- distribution from a combustion-pro- sible magnitude of variations in visibility.) duced fume. G.METHODS FOR DETERMINING LIGHT 3. if visual observations are used, the line of sight cannot pass through SCATTERING COEFFICIENT-MASS smoke plumes or freshly formed CONCENTRATION RELATIONSHIP clouds of fumes. As mentioned ear- Methods for determining the extinction lier, the light extinction coefficient is coefficient and/or the visibility (as related a spatial variable and thus the mass through equation 3-3) are not as well-es- inferred by visual methods repre- tablished as for many meteorological quan- sents an average over a large dis- tities(e.g. wind, temperature) or for air tance. If the optical quantity (i.e. ex- pollution quantities (dustfall, mass concen- tinction coefficient due to scatter) is trations, etc.). Three basic approaches can to be related to concentration meas- be differentiated: urements made at one point in space, 1. the method of choice is an instantane- then it should be determined at the ous point measurement of the ex- same point. To illustrate the possible tinction coefficient. The extinction co- magnitude of the visibility variation, efficient due to scatter (which is as- Figure 3-8 shows the variation of sumed to dominate) can be measured scattering coefficient measured with with an integrating nephelometer an integrating nephelometer across such,as wasused by Charlson the city of Seattle on three days with et al.".26. 26 different meteorological conditions. 2. the next most desirable methods in- The results also emphasize the haz- volve the measurement of total ex- ards inherent in visual observations." tinction coefficient using light trans-

1.70 59 C..

mission. Telephotometers of the is related to the visual range of a black ob- shortest possible base line might be ject as follows: used, but once again have poor sen- 3.9 sitivity for typical urban haze. Spe- L,= (m) (3-3) cially devised instruments have been bent designed and used with great diffi- Suspended particulates found in the atmos- culty in the range of extinction found phere cover a broad range of size; however; in cities. Typical airport transmis- the visibility is affected by a relativelynar- someters are designed to be useful in row segment of this size distribution, usually fog and are thus of little value except from. about 0.1it to 1it radius. Once particu- in cases of extreme pollution and fog. late matter has been suspended in the air for 3. visual methods, though frequently some time, the distribution of particles by i used, should be avoided because of size tends to take on a typical pattern. Be- .the subjectivity of the eye asa sen- cause of this, and because the visible light sor and the variations between ob- scattering is caused primarily by particles servers, as well as the spatial varia- of one narrow size range, the scatteringcan tion problem mentioned above. If it be empirically related to the particulatecon- Is necessary to use visual observa- centration. This relationship is as follows: tions, the -observers must be methodi- A x 103 cal and should use the rules adopt- (from 3-9) ed by the United States Weather G' Bureau." where G' =particle concentration (µg /m') Ordinary methods (i.e. the high-volume L, = equivalent visual range air sampler) for the determination ofmass A =1.2o a for L. expressed in kilome- concentration (µg /m') may suffice if ters and care is 0.7515 for L, expressed in miles. taken to eliminate spurious large particles 238 . such as insects, etc. As recent data takenin The ranges that are shown for the constant, Seattle show, newer sampling methods using A, cover virtually all cases studied. Devia- newer types of filters are becoming available tions from equation 3-9 would be expectedto and allow a much shorter sampling time. occur when the relative humidity exceeds 70 percent, since many particles exhibit deli- H. SUMMARY quescent behavior and grow into fog droplets. (For a discussion of the relationship] - The visual range, sometimes called the between visibility and sulfur dioxideconcen- "visibility," is reduced by particulatematter trations at various relative humidities,see in the air. It refers to the distance atwhich a companion volume to this document, Air it is just possible to perceive and object Quality Criteria for Sulfur Oxides.) Parti- against the horizon sky. Both theattenua- cles composed of sodium chloride, forex- tion of light from the object and illumination ample, would act as condensation nucleiand of the air between the object andthe ob- show rapid and large changes in sizeunder server tend to reduce visibility, since they such circumstances. Also, this relationship reduce the perceived contrast betweenthe may not hold for photochemical smog, since object and its background. Attenuationof it is not known whether its size distribution light passing through the air resultsfrom conforms to the necessary pattern. two optical effects which air moleculesand Equation 3-9 provides a convenientmeans small particles have on visible radiation:(1) for estimating the expected visibility fordif- the absorption of lightenergy and (2) the ferent levels of particulate concentrations, scattering of light out of the incident beam. under the conditions stated. Witha typical In general, reduced visibility is primarilya rural concentration suchas 30 µg /m', the result of scattering due to particulatemat- visibility is about 25 miles; forcommon ter. The, "extinction coefficient," b,,st,is a urban concentrations, suchas 100 µg /m' measure of the degree of scattering, and it, and 200 itg/ms, the visibility would be7.5 60 071 t.

miles and 3.75 miles, respectively. In addi- 10. Conner, W. D. and Hodkinson, J. R. "Optical tion to aesthetic degradation of the environ- Properties and Visual Effecteof Smoke-Stack Plumes." U.S. Dept. of Health, Education, and ment, reduced visibility has many conse- Welfare, National Center for Air Pollution Con- quences for the safe operation of aircraft trol, PHS-Pub-999-AP-30, 1967. and motor vehicles. When airports have 11. Went, F. W. "Dispersion and Disposal of Or- heavy traffic, visibility below 5 miles tends ganic Materials in the Atmosphere." Preprint to slow operations, since it is necessary to Series 31, University of Nevada, Desert Re- search Institute, 1966. maintain larger distances between aircraft. 12. Pilat, M. J. and Charlson, R. J."Theoretical Federal air regulations prescribe limitations and Optical Studies of Humidity Effects on the on aircraft operating under conditions of re- Size Distribution of a Hygroscopic Aerosol." J. duced visibility; they become increashgly Rech. Atmospheriques, Vol. 2, pp. 165-170, 1966. severe as the visibility decreases from 5 18. Charlson, R. J., Horvath, H., and Pueschel, R. F. "The Direct Measurement of Atmospheric Light miles (150 pg/ms) to 3 miles (250 pg/ms) Scattering Coefficient for Studies of Visibility to one mile (750 µg /m9) . Based on the empir- and Air Pollution."Atmos. Environ., Vol. 1, ical variations in equation 3-9, the same vis- pp. 469-478, 1967. ibilities could occur under certain circum- 14. "California Standards for Ambient Air Quality stances, at concentrations one-half of these and Motor Vehicle ExhaustTechnical Report." Dept. of Public Health, Berkeley, California, calculated values. Thus; a concentration of 1960. 75 µg /m9 might produce a visibility of 5 15. Friedlander, S. K. and Wang, C. S. "The Self- miles in some instances. Preserving Particle Size Distribution for Co- agulation by Brownian Motion." J. Colloid In- terface Sci., Vol. 22, pp. 126-132, 1966. I.REFERENCES 16. Whitby, K. T. and Clark, W. E. "Electric Aero- solParticle Counting and Size Distribution 1. Holzworth, G. C. "Some Effects of Air Pollu- Measuring System for the 0.15p to1p, Size tion on Visibility in and near Cities." In: Air Range." Tellus, Vol. 18, pp. 573-586, 1966. Over Cities Symposium, U.S. Dept. of Health, 17. Peterson, .C. M. and Paulus, H. J. "Microme- Education, and Welfare, Robert A. Taft Sani- teorological Variables Applied to the Analysis! tary Engineering Center, Cincinnati, Ohio, Tech- of Variation in Aerosol Concentration and Size." nical Report A62-5, 1961, pi. 69-88. Preprint. (Presented at the 60th Annual Meet- 2. Robinson, E. "Effects of Air Pollution on Visi- ing, Air Pollution Control Association Cleve- bility."In: Air Pollution, Chapt. '11, Vol. 1, land, Ohio, June 11-16, 1967.) 2nd edition, A. C. Stern (ed.), Academic Press, 18. Mie, G."Beitriige zur Optik triiber Medien, New York, 1968, pp. 849-400. Speziell Kolloidaler Metallosungen." Ann. 3. Middleton, W. E. K. "Vision Through the Atmos- Physik, Vol. 25, pp. 377 - 455,1968. phere." University of Toronto Press, 1952. 19. Pueschel, R. F. and Noll, K. E. "Visibility and 4. "Federal Aviation Regulations." Federal Avia- Aerosol Size Frequency Distribution." J. Appl. tion Agency, 1967. Meteorol., Vol. 6, pp. 1045-1052, 1967. 5. "A Study of PollutionAir." A staff report .20. Charlson, R. J., Ahlquist, N. C., and Horvath, H. to the Committee on Public Works, U.S. Senate, "On the Generality or Correlation of Atmo- Washington, D.C., 1967. spheric Aerosal Mass Concentration and Light 6. "New York-New Jersey. Air Pollution Abatement Scatter." Atmos. Environ., Vol. 2, pp. 455-464, Activity, Phase HParticulate Matter."U.S. 1968. Dept. of Health, Education, and Welfare, Na- 21. Noll, K. E., Mueller, P. K., and Imada, M. "Visi- tional Center for Air Pollution. Control, Wash- bility and Aerosol Concentration in Urban Air." ington, D.C., 1967. Atmos. Envir- on., Vol. 2, pp. 465-475, 1968. 7. "Kansas City, Kansas-Kansas City, Missouri, 22. Charlson, R. J. "Atmospheric Aerosol Research Air Pollution Abatement Activity, Phase II at the University of Washington." J. Air Pol- Pre-conference Investigations."U.S. Dept. of lution Control Assoc., Vol. 18, pp. 652-654, 1968. Health, Education, and Welfare, National Cen- 23. Goetz; A., Preining, 0., and Kallai, T. "The ter for Air Pollution Control, Washington, D.C., Metastability of Natural and Urban Aerosols." March 1968. Rev. Geofis. Pura Appl. (Milano), Vol. 60, pp: 8. Angstrom, A. K. "On the Atmospheric Trans- 67-80, 1961. mission of Sun Radiation II." Geograph. Ann. 24. Acheson, D. T. "Vapor Pressures of Sathmted (Stockholm), Vol. 12, pp. 139-159, 1980. Aqueous Salt Solutions." Proc. Intern. Symp. 9. lunge, C. E. 'Air Chemistry and Radioactivity." Humidity and Moisture, Washington, D.C., May Academic Press, New York, 1963. 1968, pp. 521-580.

'472 61 .; 25. Ahlquist, N. C. and Char leon, R. J. "Measure- Air." J. Air Pollution Control Assoc.,Vol. 17, ment of the Vertical and Horizontal Profileof pp. 467-469, 1967. Aerosol Concentration in Urban Airwith the Integrating Nephelometer." Environ. Sci. Tech- 27. "Manual of Surface Observations(WBAN)." nol., Vol. 2, pp. 363- 366,1968. Circular N, 7th Edition 26. Ahlquist, N. C. and Charlson, (Revised to include R. J. "A New In- changes 1 through 14), U.S. WeatherBureau, strument for Evaluating the Visual Qualityof January 1968.

62: Chapter 4

EFFECTS OF ATMOSPHERIC PARTICULATE MATTER ON MATERIALS Table of Contents Page A. INTRODUCTION 65 B. EFFECTS OF PARTICULATE MATTERON METALS 65 C. EFFECTS OF PARTICULATEMATTER ON BUILDING MATERIALS 69 D. SOILING ANDDETERIORATIONOF PAINTED SURFACES 71

E. SOILING AND DEGRADATIONOF TEXTILES 71 F. SUMMARY 72 G. REFERENCES 74 List of Figures Figure 4-1 Plot of Rate of Rusting Versus Dustfallat Four Locations 66 4-2 Weight Loss from Zinc Specimenas a Function of Exposure Time 67 4-3 District Building, Washington, D. C :67 List of Tables z Table 4-1 Corrosion of Open-Hearth Iron Specimensin Different Locations 66 4-2Corrosivity of Atmospheres towards Steeland Zinc at Selected Loca- tions Relative to that at State College 68 4-3 The Corrosion Rates of Metals in VariousLocations 70 Chapter 4 EFFECTS OF ATMOSPHERIC PARTICULATE MATTER ON MATERIALS

A.INTRODUCTION Those partticles which are inactive and Airborne particles may damage surfaces have negligible capacity for absorption or merely by settling on them. A light deposit of adsorption have little effect other than, that dust makes surfaces appear dingy, and the of acting as droplet nuclei in the atmosphere. frequent cleaning necessary in a dusty atmos- For example, silica particles do not acceler- phere weakens materials and costs money. ate the rate of metal corrosion even in the Particles can also cause direct or chemical presence of 802. On the other hand, char- deterioration of materials. The nature and coal(carbonaceous)particlesin atmos- extent of the deterioration depends on the pheres with relative humidities below 100 chemical activity of the particles in their en-, percent cause a large increase in the rate of vironment and the relative susceptibility of corrosion in the presence of SO2 traces, pre- the receiving material. Particles may cause sumably through the local, concentration of chemical deterioration either by acting as the gas by adsorption., The laboratory re- condensation nuclei for the retention of ad- search which led to these findings was based sorbed gases or harmful acids, or by their on particulate concentrations of 0.4 mg /cm= own innate corrosive action. (equivalent to 0.3 tons /mil) and abnormally In the following sections it will be seen high SO2 concentrations of 100 ppm. that particulate air pollution plays an impor- Active hygroscopic particles such as sul- tant role in the corrosion of metals; in the fate and Chloride salts and sulfuric acid aero- soiling, damage, and erosion of coatings and sol serve as corrosion nuclei. Their presence painted surfaces, building stones, marble, in the atmosphere can initiate corrosion, even and other building materials; and in the soil- at low relative humidities.5 Laboratory stud- ing and degradation of textiles. ies of bare and varnished steel test panels, properly polished and degreased, and then inoculated with finely divided particles of B.EFFECTS OF PARTICULATE MATTER various substances such as are commonly ON METALS found in the atmosphere, were conducted by Atmospheric particles may accelerate the Preston and Sanya1.5 Particles of chloride, corrosion of iron, steel, and various nonfer- sulfate, chromate, and oxide salts, and boiler rous metals. and flue dusts were used. The metal test pan- Metals are generally resistant to attack in els were exposed to atmospheres of pure dry air,' and even clean moist air does not clean air and of air containing SO2 at vari- cause significant corrosion .I, 2 Furthermore, ous humidities, and the resulting corrosion inert dust and soot particles without sulfur was measured. Filiform corrosion, character- compounds as constituents do not of them- ized by a filamental configuration, the pYi- selves cause marked corrosion.1.5 Particles mary phase in electrolytic corrosion, was may, however, contribute to accelerated cor- noted in all cases. Corrosion rates are low rosion in two ways.* First, they may be in- when the relative humidity is below 70 per- trinsically active, and secondly, although in- cent, but they increase at higher humidi- active, they may be capable of absorbing or ties.,.In most of the cases in this study, adsorbing active gases (such as SO2) from corrosion increased with increased humidity the atmosphere. even in clean air. The addition of traces of

."41 1176 SO2 to the test atmosphere greatly increased the rate of corrosion in all instances.5 Field experiments show that the rate of corrosion of various metals is accelerated in urban and industrial areas because of the greater atmospheric concentrations of both particulate matter and sulfur compounds. Standardized open-hearth iron specimens, after exposure for one year ata number of diverse locations throughoutthe world, were observed by Hudson' to havea manifold variation in weight loss. Iron specimensex- posed for one year to desert and arcticen- vironments, the least pollutedareas, were 0 16 the least corroded, 32. 48 64 80 96 i.e., had the smallest DUST FALL, TONS / M12 MONTH losses in weight. Those speimens exposedat heavily-polluted urban industrial siteswere FIGURE4-1. Plot of Rate of Rusting Versus Dust- the most corroded, moreso than similar fall at Four Locations.' (The figure plots therate specimens exposed at many marine and trop- of rusting of mild steel versus dustfall, andshows ical locations, Table 4-1. Hudson, Figure4-1, that corrosion is four times as rapid inan industrial area (Sheffield) as it is in the ruralarea also correlated the rate of rusting of mild (Llanwrtyd Wells) ). steel specimens and dustfall levels for four diverse areas, from a heavily industrialized rosion rates of steel and zinc panels exposed area in Sheffield, England, to a ruralarea for one year at several locations in theUnited (Llanwrtyd Wells). The iron specimenscor- States. The relative corrosivities of various roded four times as fast in the polluted in- atmospheres at 19 sites were comparedto dustrial atmosphere as they did in therural that of the rural site of State College,Penn- atmosphere. sylvania, which was usedas a base. This COmmittee B-6 of the American Society study (Table 4-2) confirms Hudson'sob- of Testing Materials (ASTM) s, 9 studiedcor- servations that industrial locationswith Table 4-1.CORROSION OF OPEN HEARTH IRON SPECIMENS IN DIFFERENTLOCATIONS.'

Location Annual Relative Type of atmosphere weight C0170. loss, g sivity Khartoum, Sudan Dry inland 0.16 1 Abisko, North Sweden Unpolluted Aro, Nigeria 0.46 3 Tropical inland 1.19 8 Singapore, Malaya Tropical marine Basrah, Iran 1.86 9 Dry inland 1.39 9 Apapa, Nigeria Tropical marine State College, Pa., USA 2.29 16 Rural 8.76 26 Berlin, Germany Semi-industrial Llanwrtyd Wells, British Isles 4.71 82 Semi-marine 6.23 86 Calshot, British Isles Marine Sandy. Hook, N.J., USA 6.10 41 Marine-mmi-industrial 7.84 60 Congella, South Africa Marine Motherwell, British Isles 7.84 60 Industrial 8.17 66 Wcolwich, British Isles Industrial Pittsburgh, Pa., USA 8.91 60 Industrial 9.66 Sheffield Univ., British Isles 66 Industrial 11.63 78 Derby South End, British Isles Industrial Derby North End, British Isles 12.06 81 Industrial 12.62 Frodingham, Britisii Isles 84 Industrial 14.81 100

66 high concentrations of particles and of ox- concentrations in the atmosphere are greater ides of sulfur are more corrosive to steel and than in spring) corroded 6.0 and 3.7 times as zinc than less industrialized areas. As shown much respectively as similar steel and zinc in Table 4-2, steel specimens corroded in one speciments at Sate College." The authors of year approximately 3.1 times as much in the resulting papers did not give mean con- New York City (spring exposure) and 3.3 centrations of suspended particulate matter times as much in Kearny, New Jersey, as for the various locations; but approximate similar specimens at State College, Pennsyl- concentrations, based on NASN measure- vania. Zinc specimens corroded 3.6 and 2.6 ments 10 made after the corrosion studies, are times as much in New York City (spring ex- given here. Based on Table 4-3, a town the posure) and Kearny respectively, as similar size of State College, Pa., could have a mean specimens exposed at State College. Both suspended particulate-matter level of 60 14/ steel and zinc specimens in New York City m3 to 65 pg/ms. The mean suspended par- (fall exposure when the particle and SO ticulatematter concentrations were 176

Table 4-2.-CORROSIVITY OF ATMOSPHERES TOWARDS STEEL AND ZINC AT SELECTED LOCATIONS RELATIVE TO THAT AT STATE COLLEGE, PENNSYLVANIA .°

Relative corrosivity Location Type of atmosphere of one-year test for Steel Zinc

Norman Wells, N.W.T., Canada Polar-Rural 0.03 0.4 Esquimalt, Vancouver Is., Canada Rural-Marine 0 . 6 0.4 Saskatoon, Sask., Canada Rural 0 . 6 0.5 Perrine, Fla Rural 0 . 9 1.0 State College, Pa Rural 1.0 1.0 Ottawa, Canada Semi-Rural 1.0 1.2 Middletown, Ohio Semi-Industrial 1.2 .9 Trail, B.C., Canada Semi-Rural 1.4 1.6 Montreal, Que., Canada Industrial 1 . 6 2.2 Halifax, N.S., Canada Rural-Marine 1 . 5 1.6 South Bend, Pa Semi-Rural 1 . 5 1.6 Kure Beach, N.C., 800-ft site Marine (800 ft from ocean) 1 . 8 1.7 Point Reyes, Calif Marine_ 1.8 1.8 Sandy Hook, N.J Industrial-Marine 2.2 1.6 New York, N.Y. (spring exposure) Industrial 8.1 3.6 Kearny, N.J Industrial 3.3 2.6 Halifax, N.S., Canada Industrial -Marine b 3 . 8 .18.0 New York, N.Y. (fall exposure)_ Industrial 6.0 3.7 Daytona Beach, Fla Marine 7.1 '2.6 Kure Beach, N.C., 80-ft site Marine (80 ft from ocean) 18.0 6.7

While test site is 1600 ft. from brackish water, prevailing winds are from inland and prevent deposition of salt water spray. b Test site is near a smokestack; prevailing winds blow fumes over the test site.

Table 4-3.-THE CORROSION RATES OF METALS IN VARIOUS LOCATIONS: Corrosion rate, mil/year Test Site Nickel Monel Copper 200 alloy 400

Altoona, Pa. (Heavy industrial-R.R.) 0.222 0.076 0.066 New York, N.Y. (Urban-industrial) 0.144 0.062 0.064 State College, Pa.. (Rural-farm) 0.0086 0.007 0.017 Phoenix, Ariz. (Rural-semiarid) 0.0016 0.002 0.006 fig/main New York City and 131 fig/m3 at Elizabeth, New Jersey, near Kearney," it should be pointed out that there are signifi- 9 cant differences in levels of gaseous pollution, particularly sulfur dioxide, between State College and the larger industrial communities. Consequently, the differences in corrosion rates cannot be solely attributed to the effects of 'particulates. In Chicago and St. Louis, steel panels were exposed at a number of sites, and measurements were taken of corrosion rates and of levels of sulfur dioxide and particulates." In St. Louis, except for one exceptionally polluted site, corrosion losses correlated well with sulfur dioxide levels, averaging 30 per- 4 cent to 80 .percent higher than corrosion cc losses measured in nonurban locations. Over Si3 a 12-month period in Chicago, the corrosion 0 rate at the most corrosive site (mein SO2 level of 0.12 ppm) was about 50 percent 2 SOUTHBEND, PA higher than at the least corrosive site (mean SO2 level of 0.03 ppm). Sulfation rates in. St. Louis, measured by lead peroxide candle, also correlated well with weight loss due to corrosion. Although suspended particulate 1 2 3 4 5 6 levels measured in Chicago with high-volume EXPOSURE, YEARS samplers correlated with corrosion rates,a covariance analysis indicated that sulfur di- FIGURE4-2. Weight Loss from Zinc Specimen as a oxide concentrations had the. dominant in- Function of Exposure Time' (The figure shows fluence on corrosion. Measurements of dust- the rate of corrosion of zinc at four locations in the United States, and indicates that corrosion is fall in St. Louis, however, did not correlate more rapid in industrial areas.) significaritl'ir with corrosion rates. Basedon these data, it appears that considerablecor- of particles and sulfur oxides producesa rosion may take -place (i.e., from 11 percent steeper rate of corrosion of zinc than that to 17 percent weight loss in 'steel panels) at of Kearny, New Jersey, which is also heavily annual average sulfur dioxide concentrations polluted. Zinc corrodes at a greater rate in the range of 0.03 ppm to 0.12 ppm, and in both industrial communities than in the although high particulate levels tend toac- rural or semirural sitesin South Bend, company high sulfur dioxide levels, the sul- Pennsylvania, 'and State College, Pennsyl- fur dioxide concentration appears to have the vania.' more important influence. Studies of the effects of air pollutionon Comparative studies of the rates ofcor- the atmospheric corrosion of three metals rosion of zinc-coated steel panels exposed (nickel 200, Monel alloy 400, and copper) to various community atmosphereswere con- exposed to four diverse atmospheres (heavy- ducted by Committee B-3 of the ASTM.9 The industrial, urban-industrial, rural-farm, and corrosion rates of. zinc at four of the loca- rural- semiarid) were conductedover a 20- tions over a six-year period are shown in year period.' Nickel 200 is 99.5 percent nickel Figure 4-2, as weight lossversus time. For and Monel 400 is essentially 30 percentcop- each location, the corrosion rate is essential- per and 70 percent nickel. Though these ly constant with time. The atmosphere of metals are relatively corrosion-resistant, it New York City with greater concentration will be noted from Table 4-3 that theyare 68 - ( ti9 corroded more inindustrial atmospheres avoided or minimized only by fabricating the than in rural ones. However, because of the electrical contacts out of nonreactive metals, corrosion resistance of the metals, all of the by encapsulation, or by air purification de- rates are relatively low when compared to vices such as filters or by gas-absorbing those for unalloyed iron or steel. In the in- chemicals. Any of these solutions to the prob- dustrial locations, nickel 200 corroded at lem increases costs. rates two to four times greater than Monel (nickel-copper) alloy 400, while in the rural C. EFFECTS OF PARTICULATE MATTER locations, its corrosion rate was about equal ON BUILDING MATERIALS to that of Monel alloy 400, and only one-half Building materials and surfaces are soiled, the rate for copper. Even Monel 400, with disfigured, and damaged by atmospheric par- its superior corrosion resistance, when used ticles. Some of these stick to surfaces of as a gutter in an industrial installation, be- stone, brick, paint, glass, and composition came pitted when the soot was permitted to materials, forming a film of tarry soot and accumulate.9 Unburned carbon in the soot grit which may or may not be removed by led to the formation of local galvanic cor- the action of the rain. The result is a dingy, rosion cells. The result was premature per- soiled appearance (Figure 4-3), aloss in foration and accelerated attack of the metal aesthetic attractiveness and, in many cases, sheet. a physical-chemical degradation or erosion of Larrabee '2 confirmed that the corrosion these surfaces. resistance of steel is greatly improved by the In cities where large quantities of soot- addition of small amounts of copper, or low providing fuel are burned, the problem is alloys of chromium, nickel, copper, and phos- particularly severe. Much .money and effort' phorus. The additional cost of such alloy have been.spent on sandblasting off the sooty steels when they are used to resist atmos- layers which have accumulated on prominent pheric corrosion is attributable to air pollu- buildings in burning soot-produting fuel tion. cities."-17 The tarry substances or carbona- Particles can cause corrosion of electronic ceous material resulting from inefficient com- gear of all types even where pervious metals bustion of soot-producing fuel are likely to are used to minimize such corrosion. Elec- he sticky and also acidic;2 if not flushed off trical instruments and electronic components by rain they will adhere to surfaces and cor- are factors of growing importance in the.rode them over extended periodi of time." computer and missile industries, and also Smoke particles may also act as a reservoir monitor and control an increasingly large for adsorbed gasesi' such as S02., and harmful share of manufacturing processes 18 Oily or acids, including sulfurous, sulfuric; and hy,, tarry particles, commonly found in industrial drochloric acids, as well as hydrogen sulfide. and urban areas, are serious factors in the Theie materials cause the deteriontion of corrosion and failure of electric contacts, many of the less resistant tyes ol mason- connectors, and components." Dust ditn act mechanically or chemically on Buildings : in polluted areas bec me un- electric contacts. It can deposit on the sur- sightly quickly and require periodic :leaning faces and interfere with electrical contact and maintenance to remove the t trry as- closure, it can become imbedded in the: sur- deposita:. In Washington D.C.. it faces of contacts, or -it can induce wear by was found necessary to clean the si ioke and abrasion if the contacts slide.", Hygro- grime from the new Supreme Court building scopic dusts, aciumulated on contacts, will even before initial occupancy (in the mid- absorb water to form thin 'electrolytic films': thirties) .14! While the soiling effect f soot is which are 'corrosive "to ::base metals.9 If the by fai the most eVident to the eye, if does not contact members are not of identical com- in itself cause the deterioration of building position, galvanic corrosion may, occur. The material. The destruction is due to acids, :"" A Iletuw 1:41:ait *itgKeic,Wlmf.5!, Rs/ -*/ +XIV* ibt FIGURE 4-3. District Building, Washington, D.C. (This photograph shows restoring appearance. The photograph was taken on October 26, 1960.) 5°6ty layers deposited on a public building, and the effect of sandblasting on D.SOILING AND DETERIORATION OF tective coatings, two sets of metal panels PAINTED SURFACES were coated with a varnish formulation un- Painted surfaces, walls, and ceilings of der a "dust-free" apparatus, and then one set homes and other buildings are soiled by tarry was removed from the apparatus so that the and other particulate substances in the at- varnish films dried in contact with the lab- mosphere. Furthermore, there are both liq- oratory air. The panels were then immersed uid and solid particles present in polluted in 3 percent aqueous sodium chloride for air in the form of fumes and mists of vary- seven and one-half months. Where the var- ing chemical composition which react with nish film had dried in "normal" laboratory painted surfaces."." The damage done is room air, considerable .rusting occurred on the panels after six months of immersion; no both.aesthetiC and material, and may affect not only buildings but also paintings and corrosion occurred on the panels dried in the other works of art. "dust-free" environment. Clearly the dust Auto finishes have been observed to be- particles that settled on the films of the pan- come pitted and stained by iron particles els during the drying period were a predominant factor in initiating corrosion of the deposited on them from a metal grinding op- metal." eration nearby,6 22 while chromic acid mist from an electroplating operation formed a The exteriors of buildings in industrial areas, when 'repainted,collect numerous brown stain on light colored cars and a black specks on their surfaces even before "blushing" on darker shades of paint. Re- the paint has dried." Within two to four painting was required because the color years. depending on the degree of particle changes were _not reversible by washing or concentration, these building exteriors are polishing.23.23 Cars parked near demolition distinctly soiled and require repainting."." operations of brick buildings have been severely dainaged by alkali mortar dust in the E.SOILING AND DEGRADATION presence of moisture." Characteristic pitting OF TEXTILES of painted surfaces is also caused by sodium Soiling of clothing, curtains, and other carbonate particles from such industrial textiles not only diminishes their aesthetic processing as soda ash manufacture. appeal but also reduces their functional ef- Water soluble chlorides and sulfates fectiveness. A garment which soils readily mostly the iron, copper, calcium, and zinc will not have the same user appeal as one saltsare commonly found in particulate which does not, even thoughits performance samples from cities 2423.24 an& in rainwa- may be equal in other respects. Economic ter.23 These water-Soluble particles are. po- costs are therefore involved both in the extra tentialsourcesof osmotic blistering of cleaning of garments which soil readily and Painted surfaces. The effects on weathering in the development and manufacture of soil- by small ,quantities of such particles have resistant textiles. been examined 21 during laboratory studies The extent of soiling of textiles, such as of accelerated aging of various paint panels. curtains, is influenced by various external The presence of ..0:1 ppm of iron in the water factors such as temperature, relative humid- in the accelerated weatherapparatuspro- dity, and wind speed. and the specific size duced yellow staining, while 0.5 ppm of cop-- and characteristics of the atmospheric par- per produced severe brown staining. These ticles. In addition, the degree of soiling is de- same effects may, be expected on natural ex- pendent on the construction and finish of the posure.", textile material and the type of fiber from Dust particles settling on wet varnish and which it is made.27 paint films Produce visible imperfections and When large particles are deposited on the reduction in the Plartriest1remictfavirta . avifona' 44tzs4.;...141" as air sweeps through the intricate channels filter for acid-laden dust and soot. Airborne between them, i.e., the material behaves as a metallic iron and zinc particles, constituents filter. The soiling of curtains and flags is an of city dust". 28' 29 are catalysts and pro- illustration of this effect. Airborne particles mote oxidation of sulfur dioxide to sulfuric can also affect the cleanliness of yarns and acid, which may contribute to textile degra- fabrics during their manufacture.. Economic dation. Curtains weakened by conditions of loss to textile manufacturers can occur unless exposure arising partly from atmospheric suitable air filters are used in manufacturing soiling and acidity give way in a character- plants." Laboratory studies by Rees," using istic manner by splitting in parallel lines a dust circulating apparatus under controlled along the folds where the greatest number conditions; show that a closely woven fabric of particles accumulated. of low porosity .best resists soiling by airborne particles. F. SUMMARY If an exposed textile material acquires an Airborne particlesincluding soot, dust, electrostatic charge, for example by friction, fumes, and mist can, according to their and is able to retain its charge, charged par- chemical composition and physicalstate, ticles of opposite sign will be attracted to it, cause a wide range of damage to materials. thereby increasing its rate of soiling." Cel- They may cause deterioration merely by lulose acetate and some of the synthetic tex- settling on surfaces and soiling them thus tiles acquire, by friction during spinning and creating a need for more frequent clean- weaving, electrostatic charges which, being which in itself weakens materials. More cause of the high insulating properties of importantly, they can cause direct chemi- these materials, are retained for a long peri- cal damage to materials in two ways: First, od of time. This results in troublesome "fog- through their own intrinsic corrosiveness, marking," caused by attraction of airborne and secondly, through the action of corrosive particles to the charged textile."' chemicals- which they may have absorbed In laboratory investigations of the electro- or adsorbed. Airborne particulates have static attraction of airborne particles to cot- been implicated in the corrosion of metals ton textiles, Rees 27 found that soiling is more and metallic surfaces; in the soiling, dam- rapid when the fabric is charged than when age, and erosion of buildings and other uncharged, and that the rate of soiling is structures; in the discoloration and destruc- increased by raising the applied electric po- tion of painted surfaces; and in the aesthetic tential (which .increases the charge density degradation and damage of fabrics and on the fabric). For any given potential, the clothing. rate of soiling appears t6 be greater for a Metals ordinarily can .resist corrosion in positively charged fabric specimen than for dry air alone, or even in moist clean air. a negatively ,charged one. Even inert dust or soot, in the absence of The vulnerability of textile fabrics and active 'chemical agents. has little effect on furnishings to the acid components of par- metal surfaces. However, hydroscopic particulate matter depends on the chemical Com- ticles commonly found in the atmosphere can position of the textiles."' Cellulosic fibers, corrode metal' 'surfaces although no other such as cotton; linen, hemp, jute, and man- pollutants may be present. This was shown made rayon are particularly sensitive to at- in laboratory studies in which steel test pan- tack from such substances as sulfurous. and els were dusted with varioui common par- sulfuric acids, r while .animal fibers, such as ticulatea. -Although corrosion rates were low wool and furs, are more'. resistant to' acid at relative humidities under 70 percent, they damage., tended to increase with increased humidity.

Curtains are particularly vulnerable to air The-addition of.sulfur dioxide to the lab- pollutants, and often,deterioratequickly oratory air greatly, accelerated the rates of hanging at open windows, soiling' occurs to corrosion snrn a airfarif.:. AVAITI whai; isrink.miasis T.

environments, the least polluted areas, to levels measured in Chicago with high-vol- heavily polluted urban industrial sites. Sam- ume samplers correlated with corrosion ples of iron, for example, have shown weight rates, a covariance analysis indicated that loss due to corrosion that is four times sulfur dioxide concentrations had the domi- greater in industrial atmospheres than in nant influence on corrosion. Measurements rural atmospheres. Steel samples corroded of dustfall in St. Louis, however, did not in one year 3.1 times as much in New York correlate significantly with corrosion rates. City (spring exposure), where the particu- Based on these data,' it appears that consid- late concentration was 176 µg /m', as in the erable corrosion may take place (i.e., from rural atmosphere of State College, Penn- 11 percent to 17 percent weight loss in steel sylvania,where the mean concentration panels)at annual average sulfur dioxide could be expected to range about 60 µg /me concentrations in the range of 0.03 ppm to to 65 igg/m3. Steel samples exposed in New 0.12 ppm, and although high particulate lev- York in the fall of the year, when the par- els tend to accompany high sulfur dioxide ticulate and sulfur dioxide levels are higher levels, the sulfur dioxide concentration ap- than in the spring, corroded 6 times faster pears to have the more important influence. than the samples at State College. Similarly, PartiCles play a significant role in coiro- zinc samples exposed in New York corroded sion and damage to electronic equipmct of about 3.6 times as much as those at State all kinds, even when precious metals are College, while zinc samples at Kearny, New used to minimize such effects. The contacts Jersey, corroded. about 2.6 times as much in electrical switches are vulnerable to chem- (the concentration was 131 µg /m° at Eliza- ical or mechanical action by, particulates. beth, New Jersey, near Kearney). The particulates commonly found in indus- It should be concluded, however, that the trial and urban atmospheres are serious fac- variation in corrosion rites referred to above tors in the corrosion and failure of electrical are due only to differences in particulate connectors and circuits. matter, since there are significant differ- The ability of particulates to damage and ences in gaseous pollutant concentrations be- soil buildings, sculpture, and other struc- tween State College and the other areas. tures is particularly great in cities where Even highly resistant metals have shown large quantities of coal and sulfur-bearing corrosionrates whichare progressively fuel oil are burned. Particles may cause de- larger over the following range of. environ- terioration to many types of masonry by ments;(1) a rural semiarid site;(2) a acting as reservoirs for the harmful acids rural farm enviornment; (8) an urban in- generated by the combustion of these fuels. dustrial area; (4)' a heavy industrial Area. In addition to direct erosion and physical In Chicago and St. Louis, steel panels were degradation of materials, particles stick to exposed at a number of sites, and measure- surfaces- with which they come in contact, ments were taken of corrosion rates and of forming a film of tarry soot and grit which levels of sulfur dioxide and particulates. In may or may not be removed by the action St. Louis, except for one exceptionally pol- of rain. The result is a dingy, soiled appear- luted site, corrosion 'losses correlated well ance, and much money and effort must with sulfur dioxide levels, averaging 30 per- be spent to sandblast off the sooty layers that cent to 80 ,percent higher than corrosion accumulate. losses measured in nonurban locations. .0ver Particles alsOmay soil the paintedsur- a 12-month period in Chicago, the corrosion faces of walls, ceilings, and the exteriors rate at the most corrosive site (mean SO2 of homes and buildings, and, under certain leVel of 0.12 ppm)' was about 50 percent circumstances, may cause them to become higher than at the least corrosive site (mean stained and pitted. Automobile finishes, for SO2 level of 0.08 *T).Sulfation orates in example, have been daniaged by partiCulate Si Trinigi mananivirl hap laanA 11 itlia tcmilla matter 'emi +tod'.frnm volvt. zinc saltsare commonly found in particu- 3.) Trans. Faraday Soc., Vol.31, pp. 1668-1700. late samples from cities andin rainwater 1935. and may cause blisteringand enhance the 5. Preston, R. St. J. and Sanyal,B. "Atmospheric weathering of painted surfaces. Corrosion by Nuclei." J. Appl.Chem., Vol. 6. pp. Particles 28-44, 1956. may settle on painted surfaces beforethe paint has dried, thus producing 6. Tice, E. A. "Effects ofAir Pollution on the At- imperfec- mospheric Corrosion Behaviorof Some Metals tions and reducing the abilityof the paint and Alloys." J. Air PollutionControl Assoc., Vol. to protect the surface. Suchsurfaces are 12, pp. 533-559, 1962. likely to soon require refinishing. 7. Hudson, J. D. "PresentPosition of the Corrosion The soiling of clothing, Committee's Field Testson Atmospheric Cor- curtains, and simi- rosion (Unpainted Specimens)."J. Iron Steel lar textiles makes themunattractive and di- Inst., Vol. 148, pp. 161-215, 1943. minishes their use. The extent of soiling 8. Larrabee, C. P. and Ellis,0. B. "Report ofa is influenced by a numberof factors, includ- Subgroup of Subcommittee VIIon Corrosiveness ing the temperature, therelative humidity, of Various AtmosphericTest Sites as Measured and the wind conditions.Small particles by Specimens of Steel and Zinc.Committee B-3, may penetrate deep into the fibers American Society for TestingMaterials." Am. of cur- Soc. Testing Mater. Proc., Vol.59, pp. 183-201, tains hanging inopen windows. Curtains 1959. weakened by such exposure to atmospheric 9. Copson, H. R. "Report ofSubcommittee VI. Com- soiling and aciditydeteriorate in a charac- mittee B-3, American Societyfor Testing Mate- teristic manner. The vulnerabilityof tex- rials." In: Corrosion of NonferrousMetals Sym- tile products to the acidcomponents of air- posium, Am. Soc. TestingMater., Spec. Tech. borne particles also depends Pub. 175, 1955. on the compo- 10. "Air Pollution Measurements sition of the material.Cellulosic fibers, for of the National example, such as cotton, Air Sampling Network (Analysisof Suspended linen, hemp, jute, Particulates, 1957-1961)." U.S.Dept. of Health, and man-maderayon, are particularly sensi- Education, and Welfare, Div.of Air Pollution, tive to attack from suchsubstances as sul- Washington, D.C., 1962. furous and sulfuric acids.In addition to 11. Upham, J. B. "AtmosphericCorrosion Studies in the aesthetic degradation Two Metropolitan Areas." J. AirPollution Con- and the nuisance trol Assoc., Vol. 17, created by particulatematter, direct costs pp. 398-402, 1967. may be associated with the 12. Larrabee, C. P. "Effectof Composition and En- increased rate vironment on Corrosion of Ironand Steel." Am. of deterioration of textiles,the extra clean- Soc. Metals, pp. 30-50, 1956. ing required, and the manufacturingex- 13. Antler, M. and Gilbert, J."The Effects of Air penses for fabrics thatare more resistant to Pollution on Electric Contacts."J. Air Pollution air pollution. Control Assoc., Vol. 13,pp. 405-415, 1963. 14. Williamson, J. B. P.,Greenwood, J. A. and, Harris, J. "The Influence ofDust Particles on G. REFERENCES the Contact of Solids." Proc.Roy. Soc., Ser. A (London), Vol. 237, pp. 560-573,1956. 1. Sheleikhovskii, 'G.V. "SmokePollutionof 15. Carey, W. F. "Atmospheric Towns." Akademiya Kommunal'nogo Deposits in Britain: Khzyaistva A Study in Dinginess." Intern.J. Air Pollution, im. K. D. Pamfilova. Academyof Municipal Econ- Vol. 2, pp. 1-26, 1956. omy im. K. D. Pamfilova. Izdatel'stvoMini- sterstva KomMunal'nogo 16. Meller, H. B. and Sisson,L. B. "Effects, of Smoke Khozyaistva RSFSR, on. Building Materials." Moskva-Leningrad, 1949. (Translatedfrom Rus- Ind. Eng. Chem., Vol. sian and Published for 27, pp. 1309-1312, 1935. the National Science 17.' Le Clerc, E. "Economic Foundation, Washington, D.0 bythe Israel Pro- and Social Aspects of Air Pollution." In: Air Pollution gram for ScientificTranslations,Jerusalem, (World Health 1961.) , Organization), Columbia UniversityPress, New York, 1961, pp: 279-291. 2. Greenburg, L and Jacobs,M. B. "Corrosion 18. Yocom, J. E. "The Deterioration Aspects of Air Pollution." Am.Paint J., Vol. 39, of 'faterials in pp. 64-78, 1955. Polluted. Atmospheres." J.Air Pollution Control Assoc., Vol. 8, pp. 203-208, 1958. a Vernon, W. H. J. "TheCorrosion bi Metals." `J. Roy. Soc. Arts, Vol .' 97,pp. 578-610;1949 '19. Cartwright; J. Nagelschmidt,G, and SkidMore, 4. Vernon. W Fr T «A J. W. '"The Study of AirPollution with tha 20. Giles, C. H. "Adsorption. II. In Air Pollution and 25. Graff-Baker, C. "The Effect of Dust Particles on in Natural Processes." Chem. Ind. (London), Vol. theElectricalResistance and Anti-Corrosive 19, pp. 770-781, 1964. Properties of Varnish and Paint Films." J. Appl. 21. Holbrow, G.L. "Atmospheric Pollution: Its Chem., Vol. 8, pp. 500-598, 1958. Measurement and Some Effects on Paint." J. Oil 26. Parker, A. "The Destructive Effects of Air Pol- Colour Chemists Assoc., Vol. 45, pp. 701-718, lution on Materials." The Sixth Des Voeux 1962. Memorial Lecture. (Presented at the Annual Con- 22. Fochtman, E. C. and Langer, G. "Automobile ference of the National Smoke Abatement Soci- Paint Damaged by Airborne Iron Particles." J. ety,Bournemouth,England,September28, Air Pollution Control Assoc., Vol. 6, pp. 243-247, 1955.) 1957. 27. Rees, W. H. "Atmospheric Pollution and Soiling 23. Tabor, E. C. and Warren, W. V. "Distribution of of Textile Materials." Brit. J. Appl. Phys., Vol. Certain Metals in the Atmosphere of Some 9, pp. 301-305, 1958. American Cities." Arch. Ind. Health,. Vol. 17, pp. 28. Petrie, T. C. "Smoke and the Curtains." Smoke- 145-151, 1958. less Air, Vol. 18, pp. 62-64, 1948. 24. Waller R. E., Brooke, A. G. F., and Cartwright, 29. Tebbens, B. D. "Residual Pollution Products in J. "An Electron Miscroscope Study of Particles the Atmosphere." In: Air Pollution, Chapter 2, in Town Air." Intern. J. Air Water Pollution, Vol. 1, 1st edition, A.C. Stern (ed.), Academic Vol. 7, pp. 779-786, 1963. Press, New York, 1962, pp. 23-40. Table of Contents Page A. INTRODUCTION 79 1. The Role of Economic Analysis 79 2. Gross Estimates 80 B. EARLY ECONOMIC STUDIES 81 1. Pittsburgh 81 2. Other Early Economic Studies 81 C. RECENT EFFORTS 81 1. Household Effects 81 2. Property Value Studies 83 3. Productivity Studies 84 D. SUMMARY 84 E. REFERENCES 85

List of Figures Figure 5-1Maintenance Frequency as a Function of ParticleConcentration in the Upper Ohio River Valley and the NationalCapital Area (for Households of Above-average Income) 82

List of Tables Table 5-1Estimated Costs Due to Air Pollution (Mellon InstitutePittsburgh Study) 81 5-2Differences in Cleaning Costs Incurred at Steubenvilleand at Union- town 82 Chapter 5 ECONOMIC EFFECTS OF ATMOSPHERIC PARTICULATE MATTER

A. INTRODUCTION The tools of economic analysis can illuminate the nature of this dilemma and can . 1.The Role of Economic Analysis even, with some qualification, indicate a way out. It is sometimes suggested, for instance, It is, perhaps, misleading to cordon off the that the monetary value of the undesirable so-called economic effects of particulate pol- consequences of not controlling air pollution lutants from the effects which are the grist be balanced against the consequences of in- of this document. All of the effects discussed stituting control. This is the thrust of the in this document have an economic dimen- much-heralded cost-benefit analysis, under sion. Some of the economic dimensions are which the decision maker must consider the easier to measure than others. It is difficult available alternatives and choose that which to determine, for example, what is the value seems most favorable.Comparisons are of preserving the health, or indeed the life, made insofar as possible in monetary terms, of individuals adversely affected by pollu- with the dollar serving as a common denomi- tion. It is somewhat easier to discover dif- nator. It is the purpose of this chapter to ferences in expenditure patterns attributable review the as-yet-small body of literature on to the presence of air pollution. the economic value of the effectslisted Difficult or easy, such valuation is a logi- throughout this volume. cally necessary part of the air quality stand- A major difficulty in assessing damages ards decision process. Communities desir- due to particulate air pollution lies in iso- ous of a more favorable environment are lating the effects of particulates from those confronted with the need for .two bodies of of other classes of air pollutants, such as sul- fact. First, there are the physical and tech- fur oxides, ozone, oxides of nitrogen, and nological laws that govern the generation, others, including odors. The present state transport, and control of air pollution. Sec- of the arts with respect to the measurement ond, there are the undesirable effects of transport, ambient dosages, and the short- pollution on man and his environment. Fur- term and long-term effects of the several thermore, these two realities conspire to pro- airpollutantsin various concentrations, duce a dilemma. On the one hand, if the durations; and conditions, demands that in- undesirable effects of air pollution are to creased attention, including an expanded be avoided, economic resources that might research effort, .be given to the determina- otherwise be used to satisfy other worthy tion of the effects of air pollution and the community objectives will have to be, used economic costs of these effects. for air pollution control instead, and, the It is a major objective of research into other objectives foregone. If, on the other the economic effects of air pollution to estab- hand, all these other objectives are retained' lish quantitative relationships between vary- undiminished,.the effects of a,polluted en- ing levels of pollution and outcomes (the vironment must be endured. It is evidenteffects of those levels) and 'ultimately to that some sort of balance must bOtruc.k. arrive at acceptable measures of the eco- Precisely where this Wince is acUeved is nomic coats attributable to them. In turn, a matter for the individual community to when such costs are averted thei become the decide. benefits of air pollution control. 2.Gross Estimates a total estimate of $103 million per year as A review of the physical effects cited in the cost of painting steel structures because previous chapters suggests the possibility of air pollution. of estimating damage factors and costs of Commercial laundering, cleaning, and dye- damages. The basic measurement procedure ing is another category of loss due to dirty involves four steps: air. In 1963, commercial laundering, clean- 1. Identification of nonoverlapping cate- ing, and dyeing costs amounted to $3,475 gories of air pollution. damage; million.' Between 1958 and 1963, these costs 2. An estimate of the total value of the were increasing by 5 percent annually. The category, regardless of the air pol- adjusted figure for this category .for 1968 lution effects; thus becomes $4,350 million. 3. Determination of an air pollution The Beaver Report found evidence sug- damage factor incorporating assump- gesting that one-third of laundry costs in tions or knowledge of the relation- England were attributable to the effects of ships between the total size of the air pollution.° A damage factor' for this category and the damages due to air category for the United States for the cost pollution; and of commercial laundering, cleaning, and dye- 4. Application of this damage factor to ing due to air pollution becomes $870 million. the total value of the category, in Transportation delays is another good ex- order to estimate the damages due ample of an economic loss. Air pollution is to air pollution and those due to the a major cause of reduced visibility. The particular pollutant. Civil Aeronautics Board reported that in For example, one category of effects is the 1962 low visibility resulting from smoke, corrosion of steel structures which necessi- haze, dust, and sand in the air possibly tates painting. An estimate might be devel- caused 15 to 20 plane crashes.? Other costs oped along the following lines. The Steel of low visibility include travel delays, diver- sions, cancellations, and the cost of trans- StructuresPainting Council,Pittsburgh-, Pa., estimated the annual cost of corrosion- portation to individuals- who wish to escape inhibiting coatings applied to steel struc- polluted areas on weekend trips. Land trans- tures at $500 million in 1965.1* This figure portationcosts may well include similar is adjusted at an annual rate of increase of losses2In air travel alone, the total costs of 6 percent,, yielding a 1968 estimate of $590 diversion, cancellation delays, and crashes million.= The Council estimated that a large were estimated at $803 million for 1960.8 proportion of the paint was applied because Today, the cost would be higher, Ifas little of factors such as humidity and chemicals. as 5 to 10 percent is attributed to air pollu- They suggested that particulate air pollution, $40 to $80 million or more is involved. tion may be responsible for, about 5 percent Automobile washing is another example. ,of the need. for corrosion-inhibiting paints.- Expenditures onautomobilewashing This factor was used to determine damages amounted to $143 million in 1963.8 This cate- due to air pollution and the cost of the paint, gory grew by almost 10 percent per year be- estimated at $29.5 million. Added to this tween 1958 and -1963. Extending this rate is the labor required to apply the paint. yields an estimate of $210 million forcar Labor is approximately 2.5 times' the cost washing in 1968. The $210 million is in- of the paint as shown fir the 1949 study by creased by another 50 percent to $300 million Uhlig3** The total paint and labor gives also, to adjust for the fact that washing by the car owner is not included in the lOwer *Estimate suPplied on March 11, 1965; contacted? figure. again on April 24, 1968; but no-further work had been done: The largest proportionof automobile **This 2.5 labor factor atill holds true, as cari be washing is probably caused by particulate seen by comparing totalrecorded,household repair air pollution. A damage factor of 80per- expenditures yeraus eigienditurea for materials inre- cept is assumed forcar washing, and ex- cent years.' In 1963, .for.example, the ratio was 2.3; penditures,for automobile lyashing/due to the effects of air pollution would be about 2.Other Early Economic Studies $240 million for 1968. A comprehensive study of the economic If this procedure could be repeated for effects of air pollution in Great Britain is nonoverlapping categories of damage due described in the Beaver Report in 1954.° to particulate air pollution, additional esti- This study considered both direct costs and mates of such damages could be developed. efficiency losses. The direct costs included laundry and domestic cleaning; the clean- B. EARLY ECONOMIC STUDIES ing, painting, and repair of buildings; the corrosion of metals and consequent cost of 1.Pittsburgh replacement and ofproviding protective One of the first comprehensive surveys of coverings; damage to goods; additional light- damage due to air pollution in the United ing; and extra hospital and medical services. States was conducted in Pittsburgh during Efficiency losses were represented by the the years 1912 to 1913 by the Mellon Insti- effects on agriculture of damage to soil, tute. The estimates in the Pittsburgh in- crops, and domestic animals; interference vestigation were based on economic losses with transport; and reduced human effi- due to dustfall and smoke and were obtained ciency due to illness. throughinterviewsofindividuals.. The . Le Clerc, writing in 1961 about economic items of cost and the total cost to the com- losses due to air pollution, cited data from munity were ascertained as shown in Table France and Great Britain, as well as some 5-1. general data on economic losses in the United The Mellon Institute investigators arrived States. The foreign data were quoted in at an annual per capita cost of $20 in 1913. local monetary units, which have varied over Health effects were not included; aesthetic the years in relation to the value of the dol- losses at the time were judged to be $5 per lar.Even those figures relating to the person above the $20.10 United States are cited in the context of the value of the dollar at the time of study. Some of the data contained estimates on Table 5-1.ESTIMATED COSTS DUE TO AIR POL- LUTION (MELLON INSTITUTE PITTSBURGH medical services; others did not 11 STUDY? In these two studies no attempt was made to relate economic losses to the ambient par- Causes of expenditure Cost ticle concentration. To smoke maker: Imperfect combustion $1,520,740 C.RECENT EFFORTS To individual : 1.Household Effects Laundry bills 1,500,000 Dry cleaning bills More recent attempts to assess specific 750,000 economic losses due to air pollution have To household: been made by Michelson and Tourin in the 'Exterior painting 330,000 Sheet metal work 1,008,000 Upper Ohio River Valley and elsewhere.12-26 Cleaning and renewing wall paper 550,000 The investigators made a comparative analy- Cleaning and renewing lace curtains 360,000 sis of Steubenville, Ohio and Uniontown, Artificial lighting 84,000 Pennsylvania. The socioeconomic and cli- To wholesale and retail stores: maticdataweregenerallycomparable, Merchandise 1,650,000 whereas the air pollution levels, using par- Extra precautions 450,000 ticle concentration (µg /m3) as an index, Cleaning 750,000 Artificial lighting 650,000 were dissimilar. Uniontown had an annual Department stores 175,000 average of 115 igg/m3, while Steubenirille had To 'quasi-public buildings: an annual average of 235 igg/m3. Office buildings 90,000 Six categories of possible loss were studied Hotels 22,000 in each community: Hospitals 55,000 1. Outside maintenance frequencies of Total $9,944,740 houses (cleaning painting, etc.) ; 2. Inside maintenance frequencies of Table 5- 2.-- DIFFERENCES IN CLEANING COSTS houses and apartments (walls, win- INCURRED AT STEUBENVILLE AND AT UN, dows,drapes,curtains,venetian IONTOWN." blinds, carpets, and furniture); Gross cost Activity Differences 3. Laundering and dry cleaning of (Steubenville over Uniontown) clothing (with distinction between Per summerandwintermaintenance Annual Capita* practices); Outside maintenance of houses $ 640,000 $17 4. Maintenance of women's hair and Insidemaintenance 'of facial care; houses and apartments1,190,000 32 Laundry and dryclean- 5. Inside maintenance of offices (cleaning, ing and painting) ; and 900,000 25 Hair and facial care 370,000 10 6. Storeoperationand maintenance (cleaning, painting, and other main- Total $3,100,000 $84 tenance items; losses due to spoilage *Based on estimated 1959 populationof 36,400. of merchandise). The average frequency of maintenanceop- Data from only the first four categories erations in Martins Ferry fell almostpre- were used in the comparative analysis owing cisely midway between those in Steuben- to the heterogeneity of the establishments ville and Uniontown. interviewed and the small number ofre- The curve relating costs of air pollution spondents for the last two categories,nos. and suspended particle concentrations, the 5 and 6.It will be noted that these items latter being used as an index of air pollu- of cost are related for the most part to the tion, was found by these investigators to be effects of particulate matter rather- than to essentially a straight line. Using these data, all air pollutants. the authors extrapolated the straight line For each loss category three tyPes of data of Figure 5-1 back to theaverage particle were sought: concentration of the rural stations of the 1. Activity frequency; National Air Sampling Network (NASN). 2. Incidence (i.e., the)proportion of the population to which various frequen- 4.5e . cies were applicable) and o 4.01.O BASED ON TWO PILOT STUDIES 3. Socioeconomic characteristics(i.e., (10 MAINTENANCE ITEMS EACH) cc 3.5 household income, educationallevel). )- - BASED ON TOTAL OF 23 ITEMS (UPPER OHIO RIVER STUDY Questionnaires were designed separately for 3.0. 'DATA ONLY) 2 each 'area of activity to collect accurate in- DE formation on frequency of maintenanceop- w=2.5 erationa. Although income datawere ob- c2.0 tained in steps of $2000, only two income 1 STEUBENVILLE categories. were used in the final 2 MARTINS FERRY_ compara- W 3 UNIONTOWN tive analysis: "less than $8000" and "over 1.0 4 SUITLAND $8000." The maintenance frequency factor -a7 5 ROCKVILLE a 6 FAIRFAX CITY was calculated, and the frequency factors .0.6. I III were converted into dollar values. 026 50 76100 126 150 176 200 250 300 MEAN ANNUAL SUSPENDED PARTICLES Table 5-2 shows the calculated extraper F° / m3) capita and _total costs incurred by Staben- FIGURE 5-1. Maintenance Frequency as a Function vine as a result of air, pollution. of Particle Concentration in the Upper Ohio River The Upper Ohio River study also included Valley and the National Capital Area (for House- a third city, Martins Ferry,- Ohio, where the holds of Above-average Income).(This figure particle concentrations shows that maintenance frequency increases al- were roughly mid- most linearly with the mean suspended particle way between those of. the first two cities. concentrations.) aa The mean annual rural station concentra- lies not so much in the estimates of cost, tion of suspended particulate matter for which are likely to vary in place and time, 1959 to 1961 was 25 p/m3. but in the estimates of differences in main- A similar investigation of comparative tenance. It should be noted that the use of costs due to air pollution was conducted by common cost/maintenance operation has the Michelson and Tourin in the metropolitan effect of understating the true difference in Washington, D.C., area in 1967. The char- expenditures for the items studied between acter of metropolitan Washington differs the two areas. markedly from that of Steubenville, the lat- The Michelson-Tourin studies have sug- ter having much heavy industry (steel mills, gested one approach to the problem of esti- etc.). The Washington pilot study was based mating the costs of some of the effects of on a selection of families in private dwellings particulate air pollution. The results of in- only. vestigations to date are highly suggestive of Four communities of the Washington, D.C. the existence of a significant relationship be- area (Rociniille Maryland; Suit land, Mary- tween the costs of household and personal land;Hyattsville, Maryland; and Fairfax maintenance and the existence of air pollu- City, Virginia)' were originally selected for tion. study because they represented extremes in A word of caution in the interpretation particle concentrations for outlying areas. of these results is in order. It is well,known At the time, they all had a large proportion that causation and statistical correlation are of middle-income families.The returned not one and the same. There are a number questionnaires were processed (according to of other factors, not investigated in the the replies) by income group. Since it was studies of Michelson and Tourin, which could expected that families in the very low and be highly correlated with air pollution, and very high income brackets would be rela- which could be casually related to the fre- tively insensitive to particulate pollution, quency with which'. the various personal hy- only the datainthe$10,000-to-$14,000 giene and property maintenance routine bracket were utilized. Deficiencies in the air studied are performed. For example, highly quality data for Hyattsville precluded its in- urbanized areas are likely to have both rela- clusion in the analysis. tively high levels of air pollution and a rela- Results from the three suburban Wash- tive abundance of the materials and skills ington communities compared quite favor- necessary, for the performance of hygiene ably with the results from the Upper. Ohio and maintenance operations (e.g., dryclean- River Valley study on the ten items which ing establishments, beauticians, etc.). More were common to both studies. Figure 5-1 work is needed to find out unambiguously shows the relationship betweeri suspended just what forces are operating. particle concentrations and maintenance frequency ratio(urban/rural) for the two 2.Property Value Studies studies combined, as well as for the Upper In 1967 the results of investigations into Ohio River Valley study alone. the effect of air pollution on property and It may be noted that in both sets of data other values in St. Louis, Syracuse, and the association between the maintenance fre- Philadelphia were published in a book by quency ratios sand suspended particulates is Dr. Ronald Ridker entitled Economic Costs taken to be linear over the range of the ac- of Air PollutionStudies in Measurement." tual data, 'rather than an :expected leveling The studies were somewhat inconclusive; out of the "curve" at extremely high con- they dealt generally with air pollution effects concentrations of particulates. Maintenance and did not attempt to isolate the effects of frequency ratios were not translated into particulates. Nevertheless, the effort repre- costs in the suburban Washington communi- sents an important methodological milestone ties because of widely different socioeco- because it describes some important attempts suggestions for the guidance of investiga- nomic losses. Economic losses would result tors. For example, in the chapter on "Soil- fiom work-loss days, reduced worker pro- ing and MaterialDamage Studies," Dr. r!activity, and a shortened productive work Ridker expresses pessimism with respect to life. At this time, it is not possible to do the value of additional studies based on more than speculate about the possible mag- analysis of currently available data and, cit- nitude of this possibly significant economic ing the high cost of surveys, proposes as loss. an alternative "a special type of experimen- Efforts to provide useful economic esti- tal approach to the gathering of the relevant mates of the effects of disease have long been economic information." a major problem for economists. Neverthe- The recommended approach would seek to less, estimates have been made for a number establish the physical and biological effects of diseases and agreement appears to be de- of various types and combinations of air pol- veloping on measurement methods.The lution in varying concentrations and dura- most economically useful measure of the tions.It would include study of the effects effects of reduced productivity would be the of weather conditions and attempt to estab- capitalized value or the; present discounted lish predictive relationships that could de- value of gross lost production.". 22 Progress scribe the amount of damage that would re- is reported in methods of valuing a human suit from specific exposure conditions. The life, apart from livelihood. All efforts tocon- resulting damage functions could then be struct acceptable estimates of the costs of subjected to economic analysis in an effort poor health or early death attributable to air to translate effects into costs. pollution depend on the results of research Ridker's studies of air pollution and prop- that can establish dependable cause and ef- erty values were limited to cross section fect relationships. studies. They tended to show an inverse relationship between property values and air D. SUMMARY pollution levels as measured by mean values The cost of painting steel structures be- for sulfation rates. cause of air pollution, particularly due to Otherinvestigato4s,includingT.D. particulate matter, has been estimated at Crocker," have demonstrated that the dif- about $100 million a year. The annual cost ference in land value between a polluted and of commercial laundering, cleaning, and dye- a nonpolluted area is an appropriate measure ing due to air pollution is estimated at $850 of potential gain from an abatement policy. million. The adverse effects of air pollution The results of property-value studies ap- on air travel were estimated minimally at pear encouraging in that they are a step in $40-$80 millionin 1960;obviously, they the direction of defining a function relation- would be greater today.Expenditures for ship between reductions in air quality and car washing, including washing by the car- economic loss. They supplement the studies owner involved, due to air pollution are esti- of effects of air pollution described previ- mated at about $250 million iit 1968. This ously. assumes the principal cause of frequent car 3.Productivity Studies washing is particulate air pollution. The Many feel and some are convinced that Michelson and Tourin studies, despite their air pollution, and especially the combination stated deficiencies, reveal a general relation- of suspended particulates with sulfur di- ship between levels of particulate air pollu- oxide, is associated with an increasing inci- tion and increased frequency of household dence of lung and respiratory ailments and maintenance operations.Unfortunately, it heart disease." is not readily possible to convert thesere- To the extent that particulate air pollu- lationships into cost relationships that would tion affects the respiratory tract andpro- be uniformly applicable to all communities. duces or contributes to illness among the Studies of air pollution and residential working population, it may substantially re- property values, while limited by data avail- duce human productivity and result ineco- ability, strongly suggest that a statistically 84 . ,. 4 significant inverse relationship may exist 9. "U.S. Census of Business: 1963, Selected Serv- between higher levels of particulate and ices Area Statistics," Vol. 7, U.S. Dept. of Com- other air pollution and residential property merce, WashingtOn, D.C., 1963, Table 1-8. 10. O'Connor, J J., Jr. "The Economic Cost of the values. Smoke Nuisance to Pittsburgh." University of Efforts to provide useful economic info- Pittsburgh, Mellon Institute of Industrial Re- mation about the effects of air pollution search and School of Specific Industries, Pitts- (particulates) on human health and pro- burgh, Pa., Smoke Investigation Bulletin 4, 1913. ductivity losses are incomplete because they 11. Le Clerc, E. "Economic and Social Aspects of depend on results of other research efforts Air Pollution." In: Air Pollution (World Health Organization), Columbia University Press, New aimed at the establishment of dependable York, 1961, pp. 279-291. cause and effects relationships. 12. Michelson,I.and Tburin, B."Comparative It may be possible to develop acceptable Method for Studying Cost of Air Pollution." grossestimates of airpollution damage Public Health Rept. Vol. 81(6), pp. 505-511, based on analysis within a group of non- June 1966. overlapping damage categories, as suggested 13. Michelson, I. and Tourin, B., "Report on Study in the introduction to this chapter. If such of Validity of Extension of Economic Effects of Air Pollution Data from Upper Ohio River efforts are carried out with care, they may Valley to the Washington, D.C. Area." Public provide useful guides to policy determina- Health Service Contract PH 27-68-22, Novem- tion.Considerably more attention needs to ber 8, 1967. be given to the physical and biological ef- 14. Michelson, I. and Tourin, B., "Household Cost fects of air pollution before definitive esti- of Living in Polluted Air Versus the Cost of Con- mates of the economic costs of air pollution trolling Air Pollution in the Twin Kansas Cities effects can be made. Metropolitan Area." Public Health Service Con- tract PH27-68-21. Such estimates are not the final step, how- 15. Michelson, I. and Tourin, B., "Household Cost ever. It will then be necessary to determine of Living in Polluted Air in the Washington the costs averted (or benefits) by a par- Metropolitan Area." Washington, D.C. Metro- ticular mechanism or. program of air pol- politan Area Air Pollution AbateMent Confer- lution control, in relation to the costs of ence, January 1968: control. 16. Huey, N. "Economic Benefit from Air Pollu- tion Control." Preprint. (Presented at the New E.REFERENCES York-New Jersey Metropolitan Area Air Pollu- 1. Steel StructurePainting Council, Pittsburgh, tion Abatement Activity, February 5, 1968.) Pa., Correspondence dated March 11, 1965. 17. Ridker, R. G., "Economic Costs of Air Pollu- tion:Studies in Measurement." Frederick A. 2. "StatisticalAbstract oftheUnitedStates: 1967." 88th edition, U.S. Bureau of the Census, Praeger, New York, 1967. Washington, D.C., 1967, Table 1067. 18. Crocker, T. D., "Some Economic Aspects of Air 3. Uhlig, Herbert H., "The Cost of Corrosion to Pollution Control with Special Reference to Polk the United States." Chem. Eng. NeNS, Vol. 27, County, Florida." Research Report to U.S. Pub- pp. 2764-2767, 1949. lic Health Service, Grant AP-00389. 19. Committee on 4. "Statistical Abstract of the United States, 1967." Pollution,NationalResearch 88th edition, U.S. Bureau of the Census, Table Council, "Waste Management and Control." A 1193. Report to the Federal Council for Science and Technology, National Academy of Science, Na- 5. "U.S. Census of Business: 1963, Selected Serv- tional Research Council, Washington, D.C., Pub. ices." Vol. 6, U.S. Dept. of Commerce, Washing- 1400, 1966. ton, D.C., 1963, Table I. 20. "Restoring the Quality of Our Environment." 6. "Committee on Air Pollution Report, A Report Environmental Pollution Panel, President's Sci- to the Minister of Housing and Local Govern. ence Advisory Committee, The White House, ment, Sir Hugh Beaver, Chairman." Her Majt November 1965. esty's Stationery Office, London, 1954. 21. Weisbrod, B. A., "Economics of Public Health." 7. "The Polluted Air We Breathe." American Fed- University of Pennsylvania Press, Philadelphia, erationist, Vol. 71(2), pp. 6-11, 1964. 1961. 8. Fromm, Gary, "Civil Aviation Expenditures," 22. Klarman, 'H. E., "Syphillis Control Programs." In: Measuring Benefits of Government Invest- In-: Measuring the Benefits of Government In- ments, The Brookings Institution, Washington, vestments, R. Dorfman (ed.), The Brookings D.C., 1965, Table 2. Institution, Washington, D.C., 1965. Chapter 6

EFFECTS OF ATMOSPHERIC PARTICULATE MATTER ON VEGETATION Table of Contents Page A. INTRODUCTION 89 B. EFFECTS OF SPECIFIC DUST ON VEGETATION 89 L Cement-Kiln Dust 89 a. Direct Effects 89 (1) Nature of Dust Deposition 89 (2) Range of Effects 91 (3) Dust Components Involved 92 b. Indirect Effects 93 2. Flourides 93 3. Soot 94 4. Magnesium Oxide 94 5. Iron Oxide 94 6. Foundry Dusts 94 7. Sulfuric Acid Aerosols 94 C. EFFECTS OF DUSTS ON ANIMALS BY INGESTION OF VEGETATION 95 D. SUMMARY 95 E. REFERENCES 96

List of Figures Figure 6-1Bean Plants Dusted with Cement-Kiln Particles 90 6-2Cement-Kiln Dust on Fir Tree Branches 91 6-3 Cement-Kiln Dust on Fir Tree Branches 91

I j

88 Chapter 6 EFFECTS OF ATMOSPHERIC PARTICULATE MATTER ON VEGETATION

A. INTRODUCTION composition of wastes from different kilns operating at different efficiencies varies con- Little is known abOut the effects of par- siderably, and at times the effluents may con- ticulate matter on vegetation and little retain cementitious materials that more prop- search has been done on the subject. There erly belong in the finished product. Another has been far more research on gaseous pol- important factor to consider is that literature lutants, many of which' are readily recog- reports describing effects.of dust deposited nized as serious toxicants to a variety of on various plants in the field relate to kiln- plants.Published= experimentalresults, stack materials, whereas experimental dusts mostly from Germany, are confined princi- applied in laboratory or field studies were pally to settleable dusts emitted from the taken from various collectors in the waste- kilns of cement plants. There are a few re- gas system between the kiln and the stack. ports on effects of fluoride dusts, soot. and Differences in results that may be due to this particulate matter from certain types of factor have not been reconciled. metal processing. Sulfuric acid aerosols have a. Direct Effects also been studied in Los Angeles, where depo- (1) Nature of Dust Deposition.Most of sition of aciddroplets has injured the the reports concerning harmful effects of leaves of vegetation. Most of the research cement-kiln dust on plants stress the fact was related to the direct effects of dusts on that crusts form on leaves, twigs, and flow- leaves, twigi, and flowers as opposed to in- ers.As early as 1909-1910 Peirce 1 and direct effects from dust accumulation in the Parish 2 noted in California that settled dust soil. Because of the dearth of experimental in combination with mist or light rain formed results, the tenor of many reports is directed a relatively thick crust on upper leaf surfaces as much to the question, "Do dusts in fact of affected plants. The crust would not wash have deleterious effects on plants?" as to the off and could be removed only with force. question of extent of injury. It is thus rea- The central theme about which Czaja " sonable to anticipate some disagreement. builds his case for harmful effects is the crust Such information as there is refers to spe- fOrmation in the presence of free moisture. cific dusts rather than to the conglomerate He states that crust is formed because some that is usually measured as urban or rural portion of the settling dust consists of thz. dustfall (Chapter 1). The various specific calcium silicates which are typical of the pollutant dusts and their injurious effects clinker (burned limestone) from which ce- on vegetation are discussed in the following ment is made. When this dust is hydrated on sections. the leaf surface, a gelatinous calcium silicate B. EFFECTS OF SPECIFIC DUSTS hydrate is formed, which later crystallizes ON VEGETATION and solidifies to a hard crust. When the crust is removed, a replica of the leaf surface is 1.Cement-Kiln Dust often found, indicating intimate contact of Cement-kiln dust is the dust contained in dust with the leaf. The relatively thick crust waste gases from the kilns and is not derived formed from continuous deposition is con- directly from processing of cement. It is ap- fined to the upper leaf surface of deciduous parent from some reports, however, that the species 18 completely encloses needles' of

89 conifers. Prolonged dry periods durisig the the rate of 0.47 mg /cm= -day and thenex- time dust is deposited provideno opportunity posed to naturally occurring dewwere mod- for hydration, and crustsare not formed. erately damaged.' The injury (Figure6-1) Dust deposits which are not crustedareappeared as a rolling of the margins ofthe readily removed by wind or hard rain. leaves, and some interveinal tissueswere Dar ley 3 applied kiln dusts of particle size killed.Leaves which were dusted but kept less than 10p at rates of 0.05 mg/en-0-dayto dry were not injured. 0.38 mg /cm= -day to leaves for two to three Photographs taken recently in Germany days in the laboratory. Water mistwas ap- by Dar ley (Figure 6-2 and Figure 6-3)show plied several times each day. Even though incrustations of cement-kiln duston branches the dust adhered to the leaf ina uniform of fir trees. Atmospheric levels of dustin lay6t,it did not appear to be crust-like, this area were probably inexcess of 85 tons/ probably because the experimentswere of mile2-month (0.1 mg/cm2-day).Incrusta- short duration. Reduction in CO., uptakewas tions built up on the older twigs (Figure reported in these experiments. 6-2) and caused needles to fall prematurely. Leaves of bean plants dusted for two days Some of the twigs were dead and incrusta- with cement-kiln dust of 8p to 20p sizeattions were forming on the newestneedles.

FIGURE 6-1. Bean Plants Dusted with Cement Kiln Particles. (a) Control Plant;(b) Dusted but Kept Damp; (c) Exposed to Natural Dew Formation After Each Day's Dusting.'(The photograph shows the effect of dusting bean plants for two days witkphrticles (llit to 20p) froma cement kiln. The plant exposed to mois tore (natural dew) and dust is moist affected. The dusting ratewas 0.47 mg /cm' -day.) 90 ,f01211116.

.16

FIGURE 6-2. Cement-kiln Dust on Fir Tree Branches.' (Incrustation has built up on the older twigs of a fir tree exposed to a cement-kiln dustfall probably FIGURE 6-3. Cement-kiln Dust on Fir Tree Branches' in excess of 1 mg/ms-day. Needles have fallen (Very heavy incrustation on a branch of a dead prematurely.) fir tree exposed to cement kiln dust (dustfall rates probably in excess of 0.1 mg/ine-day).) The net effect was a shortening of each succeeding year's flush of growth. A dead tree of minor significance. Lecenier and Piquer had heavy incrustations on the branches (see Czaja 5) attributed the reduced yields (Figure 6-3). from dusted 'tomato and bean plants to in- (2) Range of Effeete.Peirce 1 demon- terference with light imposed by the dust strated that incrustations of cement-kiln dust layer.Darleydemonstrated that dust de- on citrus leaves interfered with light re. posited on bean leaves in the presence of free quired for photosynthesis and reduced starch moisture interfered with the rateof carbon formation. This was laterconfirmed by dioxide exchange, but no measurements of Czaja 5 and Bohne 6 in a variety of plants. starch were made. More recently, Steinhubel T compared starch Czaja 5 stated that the hydration process reserve changes in undusted commaa holly of crust formation released calcium hydrox- leaves and those dusted with foundry dust. ide. The hydrated crusts gave solutions of He concluded that the critical factor in starch pH 10-12. Severe injury of naturally dusted formation was the light absorption by the leaves, including killing of palisade and pa- dust layer, and that the influence on tran- renchyma milt, was revealed by microscopic spiration or over-heating of leaf tissue was examinatio10e alkaline solutions pene-

; trated stomata on the upper leaf surface, 2.5 g/m2 of dust. and observed that infection particularly the rows of exposed stomataon by leaf-spotting fungus, Cercosporabeticola, needles of conifer species, and injured the was significantly greater than in nondusted cells beneath. Czaja 5 stated that.on broad- plots. He postulated that the physiological leaved species with stomata onlyon the lower balance was altered by dust increasingsus- leaf surface, the alkaline solutions firstsa- ceptibility to infection. ponified the protective cuticleon the upper Pajenkamp I'reviewed the unpublished surface, permitting migrationothe solu- work of several German investigators,some tion through the epidermis to the palisade of whom had applied dust artificiallyto test and parenchyma tissues. Typical alkalinepre- plants, and stated that he was opposed to the cipitation reaction with tannins,especially view that dusts are harmful to plants.He in leaves of rose and strawberry,was evi- concluded that depositions of from 0.75 dence that calcium hydroxide penetrated g /m2- the day to 1.5 g/m2-day (the latter amountrep-, leaf tissue. Bohne a described similar"cor- resenting the maximum that might be found rosion" of tissues under the crust formedon in the vicinity of a cement factory) hadno oak leaves. harmful effect on plants. Czaja 8 has presented good histological'evi- Raymond and Nassbaum 12 also stated that dence that stomata of conifersmay be cement dusts have little effect on wild plants. plugged by dust, preventing normalgas ex- On the other hand, Guderian 18 and Wentzel change by the leaf tissue. Uninhibitedex- disagreed with Pajenkamp and stated that change of carbon dioxide andoxygen by leaf the limited evidence at best presenteda con- tissue is necessary for normal growthand tradictory picture and that Pajenkamp had development. not cited Czaja's earlier work a.15.15 They Bohnereported a marked reduction of also pointed out that a deposit of 1.5 g/m2-day growth of poplar trees located aboutone mile was not maximum, since other workers had from a cement plant after productionin the found up to 2.5 g/m2-day, and Bohnee has plant was more than doubled. Thechange in since reported weeklyaverages of up to 3.8 growth rate was determined bythe width of g/m2-day. annual rings in the wood. Darley3 observed According to Czaja; Ewert concluded that a reduction of spring growth elongationon cement-kiln dust did not clog the stomata and conifers in Germany, where the oldestnee- that the crust might havea beneficial effect dles were incrusted. He also noted thatplants as protection against transpirational losses were stunted and had few leaves in the heav- and a defense against fungi. Czaja also noted ily dusted portions ofan alfalfa field down- that the interpretation of evidence byEwert wind from a cement plant inCalifornia. is open to question becau0e control plants Plants appeared normal in anotherpart of were heavily infested with flea beetles, while the field where there wasno visible dust de- test plants were not. posit. The dusted plantswere also he /fly in- (3) Dust Components InvolvedDetail fested with aphis and it on was not clear wheth- the injury to be expected from certaince- er the poor growth was due to the aphis ment-kiln precipitator dustswas given by feeding or a direct effect of thedust. Ento- Cm*" His work is basedon comparisons of mologists suggested that the primaryeffect chemical composition of dusts and resultant of the dust may have been to eliminate aphid injury to leaf cells of a sensitivemoss plant, predators, thus encouraging high aphidpopu- Mnium punctatum. A .cut leafwas mounted lations, which in turncause poor plant in water on a microscope slide, and dust growth because of their feeding. was placed in contact with the water at theedge Anderson e observed in New Yorkthat of the cover slip. Any effect of theresultant cherry fruit set was reducedon the side of solution on leaf cells could be observed di- the tree nearest a cementplant. He demon- rectly. Eighteen of the dusts tested in this strated that the duston the stigma prevented way fell into the following categories: pollen germination. Schanbecktreated a 1. No permanent injury to living -t field planting of sugar beets birekly cells, with but some plasmolysis from thecon - t ; ' 92 centration effect of the solution; ported on unpublished work by Scheffer in 2. Slight injury to readily accessible Germany during two growing seasons, indi- cells, disruption of the cytoplism, and cating that even considerable quantities of displacement of chloroplasts; and precipitator dust applied to the soil surface 3. Severe injury to all cells of the leaflet. brought about no harmful effects and no other lasting effects on growth or crop yield Dusts were further described as follows: of oats, rye grass, red clover, and turnips. group 1, pH of 9.5-11.5, a relatively high rate The dust had a content of about 29.3 percent of carbonation, and intermediate amount limestone (analyzed as lime, Ca0) and 3.1 (19-29 percent) of clinker. phase (calcium percent potassium oxide, K20. The maximum silicates), and characterized by a high (36- rate of deposit was 0.15 mg/cm2-day. Discon- 79 percent) amount of secondary salts; group tinuous dustings were made at 0.25 mg/cm2- 2, pH about 11, a high rate of carbonation, a day to give an average of 0.075 mg/cm2-day. lower (13-16 percent) clinker phase and In one year. the yield of red clover and the characterized by a high (81-85 percent) pro- weight of turnips were higher in the dusted portion of raw feed; group 3, pH 11-12, a plots, although the yield of leaves in the latter very slow carbonation rate. and characterized crop was reduced. Acid manuring of the soil by a high (17-49 percent) clinker phase. The appeared to increase yield but the interaction greater injury was thus related to the larger of dusting and manuring was not understood. amounts of clinker phase, which in turn re- While Scheffer et al." found no direct in- suite(' in higher and prolonged alkalinity. But jury to plants, they indicated that there Czaja also pointed out that the composition might be indirect effects through changes in of dusts within the three groups was not con.: soil reaction, which in time might impair sistent, and that, although not yet demon- yield. strated, the constituents of a given dust un- Stratmann and van Haut IS dusted plants doubtedly influence one another. with quantities of dust ranging from 0.f In short-term experiments of two to three mg /cm= -day to 4.8 mg/cm2-day; dust falling days, Dar ley 3 dusted the primary leaves of on the soil caused a shift in pH to the alkaline bean plants with fractionated precipitator side, which was unfavorable to oats but fa- dust obtained from Germany. The dust con- vorable to pasture grass. tained relatively high amounts of potassium chloride, KCI. When a fine mist was applied 2.Fluorides to dusted leaves, a portion of the leaf tissue Particles containing flouride appear to be was killed (up to 29 percent) and it was pre- much less injurious than gaseous flourides to sumed that the action was due to KCI. In vegetation. Pack et al." reported that 15 later experimentsother fractions of the percent of gladiolus leaf was killed when same dust containing very little KCI caused plants were exposed four weeks to 0.79pg/m3 an almost equivalent amount of injury, thus fluoride as HF, but no necrosis developed indicating that KCI was apparently not the when plants were exposed to fluoride aerosol only factor involved. Current laboratory in- averaging 1.9 pg/m3 fluoride. Inasmuch as the vestigations with different particle-size frac- material was collected from a gas stream tions of precipitator dusts collected around Which was treated with limestone and hy- the United States have demonstrated varying drated lime, the aerosol was probably calcium degrees of injury to bean leaves when dew is fluoride. Moreover, when the accumulated formed on the leaves. There appears to be no levels of fluoride in leaf tissues were about effect from dry dusts alone. Inasmuch as the same, whether from gas or particulate, these dusts contain very little clinker phase, injury from the latter was much less. it is ap ;rent that some components other McCune et a/.2° reported an increase of than thc.,e connected directly with hydration only 4 mm tipburn on gladiolus exposed to of calcium silicates may also be responsible cryolite (sodium aluminum fluoride dust), for injury. wherein the washed leaf tissue from this (4) Indirect Effects.Pajenkampu re- treatment showed an accumulation of 29 ppm fluoride. A 70-mm increase in tipburn would necrosis was attributed to acidity of thesoot have been expected if a similar accumulation particles. Plants outside the greenhousewere had occurred from exposure to HF.Except not damaged, possibly because the particles for the slight tipburn noted above, these had been removed by rain beforesevere in- authors found that cryolite producedno vis- jury could occur. ible effects on a variety of plantsnor did it reducf: growth or yield. 4.Magnesium Oxide It is evident from the work of McCune The possible indirect effecton vegetation et at." that fluoride in plant tissue isaccumu- of magnesium oxide fallingon agricultural lated from cryolite treatment, but the rate of soils was reported by Sievers.24 He noted accumulation is much slower than would be poor growth in the vicinity of a magnesite- expected from a comparable treatment with processing plant in Washington. Experi- HF. For example, when comparing washed ments were designed to grow plants in soil leaf samples, exposure of gladiolus to HF for collected at various distances from theproc- three days at 1.01pg/ms fluoride resulted in essing plant, in normal soil and in soilto an accumulation of 26.4 ppm fluoride, where- which magnesium oxidewas added. Suppres- as only 34 ppm was accumulated from anex- sion of plant growth was demonstrated with posure to cryolite for 40 days at 1.7pg/m2 the high levels of magnesium. After theproc- fluoride: Pack et at" reported only one-third essing plant ceased operation, injury tocrops as much fluoride accumulated from particu- in the area became less pronounced,indica- late matter as fromgaseous forms. ting that the injurious effectwas not a per- Both the investigations cited above indi- manent one. cate that much of the particulate matter re.- 5.Iron Oxide mains on the surface of the leaf and can be Berge,25 in Germany, dusted experimental washed off, although that whichremains after washing is not necessarily internal plots with iron oxide at the rate of 0.15 fluoride. Reduced phytotoxicity of particulate mg/cm2-day over one- to ten-day intervals fluoride is ascribed in part to the inability of through the growing season for sixyears. the material to penetrate the leaf tissue. In The plots were planted with cerealgrains or addition, McCune et al." suggest that turnips, and effects of treatmenton the pri- in- mary product, on straw, and on leaves were activity of particles may be due to theirin- ability to penetrate the leaf ina physiologi- noted. No harmful effect of the dustwas de- cally active form. tected on either crop. Therewas a tendency for improvement of yields of grain andtur- 3.Soot nip roots, but this was not statisticallysig- Jennings 21 noted the suggeition that soot .nificant. may clog stomata and prevent normal gas ex- 6.Foundry Dusts change but that most investigationstend to Changes in starch reserveswere compared discount this effect. Microscopic examination incommon holly leaves,untreated, and failed to show enough clogging of stomataon treated with dusts emitted fromfoundry leaves of shade trees (broad-leaved species) operations.6 The criticalfactor was the to be significant. He further states that inter- amount of light absorbed by the dustlayer, ference with light can bemore serious but and the influence on transpirationor over- he offers no data from critical experimentsto heating of leaf tissue was of minor signifi- substantiate this theory. cance. These observations agree with some of A well-illustrated report by Berge22 showed those reported above on therange of effects plugged stomata on conifers growingnear of cement-kiln dust on vegetation. Cologne,Germany.. He alsostatedthat growth was adversely affected. 7.Sulfuric Acid Aerosols Necrotic spotting was observedon leaves These particles too may settleon plants of several plants where soot froma nearby and cause injury. They are not discussed here, smokestack had entered a greenhouse."The'however, as the subject is covered insome 94 detail in Air Quality Criteria for Sulfur succeeding year's flush of growth. Although Oxides, a companion document. the mechanism by which injury occurs is not entirely, understood, it is possible that the C.EFFECTS OF DUSTS ON ANIMALS BY crust intercepts the light needed for photo- INGESTION OF VEGETATION synthesis and starch formation, causes alka- Particles which contain chemical compo- line damage to tissues, and prevents normal nents detrimental to animal health may be gas exchange in leaf tissues. Injury due to assimilated through ingestion of plant ma- the direct effect of high pH on cell constitu- terials. The toxic components may be ab- ents does occur. Plugging of. stomata and sorbed into the plant tissues or may remain reduced growth of trees may occur within a as a surface contaminant on the plants. When short distance of cement plants. evaluating the potential harm to animals It should be noted, however, that the harm- from ingeSted vegetation, both absorbed and ful effect of cement dusts on vegetation is not deposited particles should be considered. fully substantiated and has been questioned Fluorosis in animals has been reported by some workers. The controversy that sur- from ingestion of vegetation covered with a rounds this subject is not surprising in view fluoride-containing particulate matter.26 In- of the limited research to date. In addition, jury occurs when absorbed plus deposited not all studies have been carried out under fluoride on the plants reached 40 ppm to 50 identical conditions or with dusts of the same ppm. Arsenic poisoning of cattle and sheep composition. Studies of the effects of cement- has occurred from ingestion of arsenic-con- kiln dusts deposited on the soil also raise taining particles settled on vegetation." questions. Some investigators repot no harmful effects at levels from 0.15 mg/cm2- D. SUMMARY day to 0.75 mg/cm2-day (130'tons/mi2-month There has been relatively little research on to 640 tons /mil- month), while others report the effects of particulate matter on vegeta- that concentrations from 0.1 mg/cm2-day to tion, and most of the experiments done to 4.8 mg/cm2-day (86(tons/mi2-month to 4,000 date have dealt with specific kinds of dusts tons /mil-month)cause shifts in the soil alka- rather than the conglomerate mixture nor- linity which may be favorable to one crop but mally encountered in the atmosphere. harmful to another. The significance of dusts as phytotoxicants Fluorides in particulate form are less dam- is not yet entirely clear but there is con- aging to vegetation than gaseous fluorides. siderable evidence that certain fractions of Fluoride may be absorbed from depositions cement-kiln dusts adversely affect plants of soluble fluoride on leaf surfaces. However, when naturally deposited on moist leaf sur- the amount absorbed is small in relation to faces. Dry cement-kiln dusts appear to have that entering the plant in gaseous form. The little deleterious effect, but in the presence fluoride from particulates apparently has of moisture the dust solidifies into a hard ad- great difficulty penetrating the leaf tissue in herent crust which can damage plant tissue a physiologically active form. The research and inhibit growth. Modezate damage has evidence suggests that few if any effects oc- been observed on the leaves of bean plants cur on vegetation at fluoride particulate con- dusted at the rate of about 0.47 mg/cm2-day centrations below about 2tig/m2. Concentra (400 tons /mil- month) for two days and fol- tions of this magnitude can be foUnd in the lowed by exposure to naturally occurring immediate vicinity of sources of fluoride par- dew. Similarly, a marked reduction in the ticulate pollution, but they are rarely found growth of poplar trees one mile from a in urban. atmospheres. Fluorides absorbed cement plant was observed after cement pro- or deposited on plants may be detrimental to duction was more than doubled. At levels in animal health. Fluorosis in animals has been excess of 0.1 mg/cm2-day (85 tons/mi2- reported due to the ingestion of vegetation month), incrustations have been observed on covered with particulates containing fluo- the branches of fir trees, with the result that rides. In a similar manner arsenic poisoning needles fell prematurely, shortening each of cattle and sheep has occulTed from in-

k .0.4104 gestion of arsenic-containing particulate that 13. Guderian, R. and Pajenkamp, H. "Einwiikang had settled on vegetation. des Zementofenstaubes auf Pflanzen und Tim." Soot may clot stomata and may produce Staub, Vol. 21, pp. 518-519, 1961. necrotic spotting if it carries with it a soluble 14. Wentzel, K. F. and Pajenkamp, H. "Einwirkung toxicant, such as one with excess acidity. des Zementofenstaubes auf Pflanzen und Tiere." Magnesium oxide deposits on soils have been Zeit. ftir Pflanzenkrankh, Vol. 69, p. 478, 1962. shown to reduce plant growth, while iron 15. Czaja, A. T. "Die Wirkung von verstaubtem Kalk und Zement auf Pflanzen." Qualitas Plant Mater. oxide deposits appear to have no harmful ef- Vegeteaes, Vol. 8, pp. 184-212, 1961. fects and may be beneficial. Sulfuric acid 16. Czaja, A. T. "Zementstaubwirkungen auf Pflan aerosols will cause leaf spotting. The levels zen : Die Entstehung der Zementkrusten." Quali- at which these materialsimay produce a toxic tas Plant Mater. Vegetabiles, Vol. 8, pp. 201-238, response are not well defined. 1961. 17. Scheffer, F., Przemeck, E., and Wilms, W. "Un- tersuchungen Ober den Einfluss von Zementofen- E.REFERENCES Flugstaub auf Boden and Pflanze." Staub, Vol. 21, pp. 251-254, 1961. 1. Peirce, G. J. "An Effect of Cement Dust on Orange Trees." Plant World, Vol. 13, pp. 283-288, 18. Stratmann, H. and van Haut, H. "Vegetations- 1910. versuche mit Zementflugstaub." (Unpublished investigations of the KohlenStoff-biologischen For- 2. Parish, S. B. "The Effects of Cement Dust on schungsstation) Essen, Germany, 1956. Citrus Trees." Plant World, Vol. 13, pp. 288-291, 1910. 19. Pack, M. R., Hull, A. C., Thomas, M. D., and 3. Dar ley, E. F. "Studies on the Effect of Cement- Transtrum, L. G. "Determination of Gaseous and Kiln Dust on Vegetation." J. Air Pollution Cun- Particulate Inorganic Fluorides in the Atmos- trol Assoc., Vol. 16, pp. 145-150, 1966. phere." Am. Soc. Testing Mater., Spec. Tech. Pub. 281, 1959, pp. 27-44. 4. Dar ley, E. F. Unpublished data. 5. Czaja, A. T. "Uber das Problem der Zementstaub- 20. McCune, D. C., Hitchcock, A. E., Jacobson, J. S., wirkungen auf Pflanzen." Staub, Vol. 22, pp. 228- and Weinstein, L. H. "Fluoride Accumulation and 232, 1962. Growth of Plants Exposed to Particulate Cryo- lite in the Atmosphere." Contrib. Boyce Thomp- 6. Bohne, H. "Schadlichkeit von Staub aus Ziment- son Inst., Vol. 23, pp. 1-22, 1965. werken fur Waldbestande." Allgem. Forstz., Vol. 18, pp. 107-111, 1963. 21.Jennings, 0. E. "Smi Ir. 'Try to Shade Trees." 7. Steinhubel, G. "Zmeny v skrobovych rezervach Proc. Nat. Shade t cee Co., l10th, 1934, pp. listov cezminy po umelom znecisteni pevnym po- 44-48. praskom." Biologia, Vol. 18, pp. 23-33, 1962. 22.Berge,H. "Luftverunreinigungen im Raume (Abstract, in German, pp. 32-33, with the title: Köln." Allgem. Forstz., Vol. 51-52, pp. 834-838, Veranderungen in den Starkereserven der Blat- 1965. ter der gemeinen Stechpalme nach einerkilnst- 23.Miller, P. M. and Rich, S. "Soot Damage to lichen Verunreinigung durch Staub.) Greenhouse Plants." Plant Disease Reptr., Vol. 8: Czaja, A. T. "Uber die Einwirkungvon Stauben, 51, p. 712, 1967. speziellvon Zementofenstaub aufPflanzen." 24.Sievers, F. J. "Crop Injury Resulting from Mag- Angew. Botan., Vol. 40, pp. 106-120, 1966. nesium Oxide Dust." Phytopathology, Vol. 14, 9. Anderson, P. J. "The Effect of Dust from Cement pp. 108-113, 1924. Mills on the Setving of Fruit." Plant World, Vol. 25.Berge, H. "Emissionsbedingte Eisenstaube und 17, pp. 57-68, 1914. ihre uswirkungen auf Wachstum und Ertrag landwirtschaftlicherKulturen." Zeit. Luft- 10. Schonbeck, H. "Beobachtungen zur Frage des vereinigung (Dusseldorf), Vol. 2, pp. 1-7, 1966. Einflusses von industriellen Immissionen auf die Krankbereitschaft der Pflanze." Berichte der 26.Shupe, J. L, Miner, M. L., Harrison,. L. E., and LawlesanstaltftirBodennutzungsschutz(Bo- Greenwood, D. A. "Relative Effects of Feeding chum), Vol. 1. pp. 89-98, 1960. Hay Atmospherically Contaminated by Fluoride Residues, Normal Hay Plus Calcium Fluoride, 11. Pajenkamp, H. "Einwirkung des Zementofen- and Normal Hay Plus Sodium Fluoride to Dairy staubes auf Pflanze and Tiere." Zement-Kalks- Heifers." Am. J. Vet. Res., Vol. 23, pp. 777-787, Gips, Vol. 14, pp. 88-95, 1961. 1962. 12. Raymond, V. and Nussbaum, R. "A propos des 27.Phillips, P. H. "The Effects of Air Pollutants on poussieres cimenteries et leurs effets sur Farm Animals." In: Air Pollution Handbook, P. Phomme, NI plants, et les animaux." Pollut. L. Magill, F. R. Holden, and C. Ackley (eds.), Atmos. is), Vol. 3, pp. 284-294, 1966. McGraw-Hill, New York, 1956.

96 Chapter 7

SOCIAL AWARENESS OF PARTICULATE POLLUTION Table of Contents. Page A. INTRODUCTION 99 B. THE STUDIES 99 1. St. Louis, Missouri 99 2. Nashville, Tennessee 100 3. Birmingham, Alabama 101 4. Buffalo, New York 101 C. SUMMARY 102 D. REFERENCES 102

List of Figures Figure 7-1Proportion of Population in St. Louis Stating Air PollutionPresent in Their Area of Residence, and Proportion of St.Louis Population Bothered 100 7-2 The Level of Air Pollution Related to PublicOpinion in Three In- come Groups (Nashville, Tennessee) 101 7-43Radial Distribution from the Center of Nashvilleof Air Pollution Levels, Socioeconomic Status and Public Concern About AirPollu- tion 101

98 01 1.07 Chapter 7 SOCIAL AWARENESS OF PARTICULATE POLLUTION

A. INTRODUCTION very little work has been done in this partic- The nuisance of air pollution is to some ular area of measuring the response of the extent a subjective perception, and its signifi- public to the nuisance of air pollution. cance is therefore influenced, to some extent It is important to note that application of by the way the public feels about pollution. present control technology may result in a Nevertheless, it is acceptable practice to con- much larger reduction in larger particles clude that nuisance and levels of pollution than in smaller particles. The remaining are related if it can be demonstrated that a smaller particles will not be as readily dis- nuisance response by a sample population is cernible to the public, and awareness of par- positively related to average levels of actual ticulate pollution may diminish. pollution. The development of such evidence The effect of particulates on the total eco- is difficult because public reaction probably logical system and man's enjoyment of his reflects pollution peaks rather than the mean environment cannot as yet be fully evaluated. value for an extended time period. This prob- B. THE STUDIES lem has been considered by McKee 1 in a recent paper. 1.St. Louis, Missouri Several studies have attempted to assess One major investigation of the relation- the annoyance to a population of community ship between public opinion and particulate air pollution, but not all have taken advan- air pollution concentrations is that conducted tage of available aerometric data to establish in the Greater St. Louis area.3.4 This area the relationships between air pollution levels comprises portions of St. Louis County, Mis- and attitudes and opinion among the affected souri, and portions of Madison and St. Clair population. The chief value of these surveys Counties, Illinois. It includes St. Louis, East lies in demonstrating that a significant pro- St. Louis, and Granite City, and thus most portion of the public is aware of, and con- of the population residing in the St. Louis cerned about, air pollution, and is willing to metropolitan area, as defined by the Bureau act to abate the nuisance.; a One of the most of the Census. Persons interviewed were obvious indications of the nuisance of air pol- asked whether they believed that sir pollu- lution is citizen complaints. Generally speak- tion was present and whether they regarded ing, the person who is willing to take the it as a nuisance. The responses were related time to telephone or write a complaint about to the pollution level measured both as sus- air pollution is probably seriously irritated by pended particle concentration and as soiling it. And those who actually complain may rep- index. (See Chapter 1 for a discussion of this resent only the top of the iceberg. There are latter measure of pollutant concentration.) many who may be irritated who will not com- Figure 7-1 shows the results obtained for plain because they do not believe complaining both questions in terms of suspended particle will do any good. There are others, conspicu- concentrations. It will be seen that the popu- ous by their absence, who have moved away lation becomes aware of pollution before it because of the effects of air pollution on their regards it as a nuisance. Where the average health, or baesuse of the aesthetic degrada- annual geometric mean of particles was 80 tions of their neighborhood. Unfortunately, µg /ma, better than 30 percent of the popula-

99 -108 sance aspects of air pollution, asking respondents to indicate whether the outside of the house got too dirty, whether automobiles got dirty too fast, and whether too much dust collected on porches and window sills. An- other question, measuring "bother" by air pollution was embedded in a series of questions relating to health, and responses to it should not be compared directly withre- sponses of general concern and nuisance in other surveys. The proportion of affirmative 50 100 150 2.00 SUSPENDED PARTICLES, lig/m3 responses to the question concerning too (ANNUAL*GEOMETRIC MEAN) much dust and dirt on porch and window sills showed a clear increase with increasing par- FIGURE 7-1.Proportion of Population in St. Louis Stating Air Pollution Present in Their Area of ticle concentrations. The data do not, how- Residence, and Proportion of St. Louis Popula- ever, permit a predictable quantitative state- tion Bothered.(This figure presents the results ment of this responsibility. obtained from interviews.) Survey results indicated that up to 3.8 percent of the respondents voluntarily ex- tion indicated awareness of air pollution. pressed awareness and concern about air Fifty percent and 75 percent of thesurvey pollution as a health problem; an extension population were aware of air pollution in the of the sample population of about 2,850 to area where the average annual levels of par- the total population indicated that this figure ticulate matter were 120 pram' and 160 pg/m3 equated to approximately 9,000 residents. respectively. None of the populationap- In response to a direct question, 23 percent peared to be bothered by particle concentra- of the respondentsor approximately 50,000 tions below 50 pg/m3, 10 percent of thepopu- residents, if the sample were projected to the lation was bothered at a level of about 80 total populationstated they were bothered pg/m3, 20 percent was bothered about 120 in some way by air pollution. Inresponse to pg/m3, 33 percent at 160 pg/m3, while 40 direct questions, several specific non-health percent regarded a concentration of 200 aspects of smogsoiling, decreased visibility, pg/m3 as constituting a nuisance. The data odors, and property damagewere cited as on the nuisance response in Figure 7-1 can affecting from 18 percent to 51 percent of be expressed approximately in the form the respondents, or between 40,000 to 100,000 yc-40.3x14 of all residents, as based on the samplepopu- lation. It was also concluded that the fre- over the range studied, where y is the per- quency of days of acute pollution had an ad- centage of the population expressing dissatis- ditional influence on the proportion of people faction, and x is the annual geometricmean who would express concern and annoyance. of suspended particle concentration in pg/I113. The study indicated'some relationships be- The equation assumes that the character oftween level of concert and socioeconomic the pollution is the same forareas of both status. At high levels of air pollution, con- high and low pollution. cern was greater among women of high socio- 2.Nashville, Tennessee economic status than among women of low socioeconomic status, although at low levels A study by Smith et al..3 reveals thecom- of air pollution, those of low socioeconomic plexity of public opinion surveys. The method status expressed more concern than those of used was similar to that in othersurveys: high status. There was also a relationship public opinion data were compared willaero- between socioeconomic status and the dis- metric data from the nearest air sampling tance of residence from the center of Nash- station. One group of questions in the public ville (the more affluent living fartheraway opinion survey dealth specifically with nui- in general). Figures 7-2 and 7-3 together 100 109 demonstrate the interlocking relationship; ship probably is not linear, they do indicate Figure 7-2 uses arbitrary scales for both that the respondents clearly defined a nui- variables and should not be taken to indicate sance situation in their area of residence at the exact form of the relationships. annual mean dustfall values of 10 tonsjmile2- month or above. 3.Birmingham, Alabama -Stalker and Robison 6 compared data from 4.Buffalo, New York 21 air sampling stations with publicre- de Groot and Samuels 2 used two independ- sponses from a sample of 7200 households. ent samples taken three years apart to Data were gathered only from people living determine public opinion. Opinions were as- within one mile of an air sampling station. sessed against aerometric data from the near- The investigators found that 10 percent of est of nine air sampling stations. The meas- the population believed a nuisance existed at ure of public opinion wag4he percentage of a seasonal (summer) mean suspended parti- the population considerine.air pollution a cle concentration between 60 pg/m3 and 180 serious community problem. The investiga- pg/m3, and more than 30 percent of the popu- tors countedonly clear,unequivocal relation believed a nuisance existed at levels sponses; respondents who indicated uncer- between 100 pg/m3 and 220 pg/ms. Theau- tainty about the seriousness of the problem thors use their dustfall data to demonstrate were assigned to the "not serious" category. that for each increment of 10 tons/mile- In :t.ffalo, as in Birmingham, there were ap- month another 10 percent of the affected parent positive relationships between public public would become concerned and consider awareness and levels both of dustfall and of that level a general nuisance. Although the published data indicates that the relation- foci

904\AIR POLLUTION INDEX

80 -

70k-

SOCIO-ECONOMIC STATUS INDEX

CONCERN ABOUT AIR POLLUTION 30- (ARBITRARY SCALE)

21)1- FIGURE7-2.The Level of Air Pollution Related t,.) INDEX OF CONCERN ABOUT Public Opinion in Three Income Groups (Nash- AIR POLLUTION ville, Tennessee).* (Figures 7-2 and 7-3 show the 10- interlocking relationships between several parameters affecting public concern over air pollution in Nashville. At high levels of pollution, concern is strongest in those of highest socio-economic RADIAL DISTANCE FROM THE CENTER OF NASHVILLE,, status, while at low pollution levels, concern is TENN., MILES greatest among those of low status. This result is possibly connected with the radial distance from .Ftsuits 7 -8. Radial Distribution from the Center of Nashville at which persons of different socioeco- Nashville of Air Pollution Levels, Socioeconomic nomic status reside.) States and Public Concern About Air Pollution.' t 1 101 suspended particles. There was also a posi- fected population expressed concern abouta tive relationship between the frequency of nuisance situation. days of acute levels of these pollutants and The available literature also indicates that public opinion. the extent to which a population considers air pollution an annoyance is related to the fre- C.SUMMARY quency of days with acute pollution as well Public opinion survey data in several cities as to the average level that the level of con- indicate a positive relationship between the cern is related to socioeconomic status, and concern expressed about air pollution bya that the population becomes aware of pollu- population and the actual levels of particulate tion at particle concentrations lower than pollution--used as an index of air pollution. those at which they consider that it consti- In general, over the ranges studied,an in- tutes a nuisance. creasing proportion of the populationex- In the St. Louis study, 30 percent of the presses dissatisfaction over air pollution as study population were aware of pollution in concentrations of particulate matter increase. areas where the annual geometric mean value However, while the several studies agree, for of suspended particulates was 80 pg/m3, 50 the most part, in this qualitative relationship, percent in areas with 120 pg/m3 and 75per- it is difficult to compare the studies quantita- cent in areas with 160 pg/m3. tively. .Each study used different sampling schemes, questionnaire schedules, and meth- D. REFERENCES ods of interviewing. In addition, the socioeconomic characteristics of the population 1. McKee, H. C. "Why a General Standard for Par- ticulates?" (Presented at the Symposium on Mr sampled varied from city to city. The St. Quality Standards: The Technical Significance, Louis data has been singled out for quantita- 156th National Meeting, American Chemical So- tive expression because it showed the most ciety, September 12, 1968.) consistent association between air pollution 2. de Groot, I. and Samuels, S. W. "People and Air and public awareness. However, it is in- Pollution : A Study of Attitude in Buffalo, New York. An Interdepartment Report." New York tended to serve only as an example. State Dept. of Health, Air Pollution Control Over the approximate range 50 pg/m3 to Board, 1965. (See also de Groot, I., Loring, W., 200 pg/m3, the expression Rihm, A., Samuels, S. and Winkelstein, W.,same title, J. Air Pollution Control Assoc., Vol. 16,pp. y=0.3x 14 245-247, 1966.) 3. "Public Awareness and Concern with Air Pollu- relates roughly the percentage of concerned tion in the St. Louis Metrdpolitan Area." U.S. St. Louis population, y, and the annualgeo- Dept. of Health, Education, and Welfare, Div.of metric mean suspended particle concentra- Air Pollution, Washington, D. C., May 1965. (See tion x (pg/m3). Thus, 10 percent of the study also Schusky, J., same title, J. Air Pollution Con- population was bothered by air pollution in trol Assoc., Vol. 16, pp. 72-76, 1966.) areas where the annual geometric mean value 4. Williams, J. D. and Bunyard, F. L. "Interstate Air Pollution Study, Phase II Project Report, of suspended particulateswas about 80. Vol. VIIOpinion Surveys and Air Quality Sta- pg/m3. About 20 percent of the study popula- tistical Relationships." 'U.S. Dept. of Health, tion was bothered in areas withan annual Education, and Welfare, Div. of Air Pollution, geometric mean value of 120 pg/m and 33 Cincinnati, Ohio, 1966. percent with a mean of 160 pg/m3. The 5. Smith, W. S., Schueneman, J. J., and Zeidberg, re- L. D. "Public Reaction to Air Pollution in Nash- sponses are probably associated with the ville, Tennessee." J. Air Pollution Control Assoc., short term fluctuations in particulate levels Vol. 14, pp. 418-423, 1964. which underlie any averaging time period. 6. Stalker, W. W. and Robison, C. B. "A Method Other studies show that when dustfall for Using Air Pollution Measurements and levels exceeded an annual mean of 10 tons/ and Public Opinion to Establish Ambient Air Quality Standards." J. Air Pollution Control miles-month, at least 10 percent of theaf- Assoc., Vol. 17, pp. 142-144. 1967.

102 1.1.1 Chapter 8 ODORS ASSOCIATED WITH ATMOSPHERIC PARTICULATE MATTER

112 Table of Contents,

Page A. INTRODUCTION 105 B. EVIDENCE FOR THE ASSOCIATION OF ODOR WITH PARTICLES 105 C. HYPOTHETICAL MECHANISM FOR THE ASSOCIATION OF ODOR WITH PARTICLES 106 1. Volatile Particles 106 2. Desorption of Odorous Matter by Particles 106 3. Odorous Particles 107 D. COMMON ODOR PROBLEMS 107 E. SUMMARY 107 F. REFERENCES 108

List of Tables Table 8-1 Most Frequently Reported Odors 107

104 Chapter 8

ODORS ASSOCIATED WITH ATMOSPHERIC PARTICULATEMATTER

A. INTRODUCTION Ott 2 showed that the removal of particulate The human olfactory sense has the ability matter from diesel exhaust by thermal pre- to detect and respond to thousands of differ- cipitation effected a marked reduction in ent materials or chemical compounds. Some odor intensity. The precipitation method was odorants can be detected in concentrations as selected because it provides minimal con- low as one part per billion. Modern instru- tact between the collected .particles and mentation lacks both the selectivity and the the gaseous components of the dieselex- sensitivity possessed by the olfactory sense haust stream. Thus, effects that could be for the detection of many odorants. produced by a filter bed, such as removal Odorants in themselves may not cause or- of odorous gases by absorption in the fil- ganic disease; however, the discomfort and ter cake, are eliminated. The observed odor disagreeableness that may be brought about reduction must, therefore. have resulted di- by obnoxious odors can cause some tempo- rectly from the removal of particulate mat- rary ill effects. The effects that border upon ter. The particles collected by Rossano and ill health include lowered appetite, lowered Ott were aggregates of spherical balls about water consumption, impaired respiration, 0.04 to 0.05ii in diameter. Particulate matter nausea, vomiting, and insomnia. from diesel exhaust collected on glass fiber Particulate matter in itself is not consid- filters by Linnell and Scott' yielded a heavy ered to be capable of directly stimulating the "diesel" odor. Analysis of the particulate olfactory sense. However, this should not be matter showed that it contained no acrolein interpreted to mean that all airborne particu- or formaldehyde, although it did release NO2 late matter, as a pollutant category, is in- on being heated to 100°C. The authors con- capable of stimulating the odor sense nor clude that "no appreciable gas :chase con- that particles cannot be involved in the de- centration changes for acrolein rif formalde- livery of the odorant to the receptor cells. hyde will result from particulate removal." There is evidence that some particles can Other more or less casual observations on the stimulate the sense of smell because the parti- role of particulate matter in community odor cle itself is volatile or because this particle is nuisance problems appear occasionally in the desorbing a volatile odorant: There is also literature.' speculation 2 that some particulate matter is A second piece of evidence that implicates capable of stimulating the sense of smell ".e- the association of particles with odors is the gardless of the mechanism of how particles production of a mild odor, sometimes de- are involved in the stimulation of the olfac- scribed as "yeasty," in air that is passed tory sense, the important fact is that they through a bed of activated carbon. Turk and definitely appear to be involved. Downes 5 have shown that this odor is not produced by any delectable desorption of B.EVIDENCE FOR THE ASSOCIATION gaseous matter from the carbon, and that OF ODOR WITH PARTICLES the same' odor can be produced by passing The idea that odors are associated with air through silica gel. 6 It is possible that particles is supported by observations that subfilterable particles are associated with filtration of particles from an odorous air this phenomenon. stream can reduce the odor level. Rossano and Evidence for the association of particulate

105 1.14 matter with outdc.or odors has sometimes C.HYPOTHETICAL MECHANISMS FOR been sought in the gross errors in odor in- THE ASSOCIATION OF ODOR WITH tensities preducted on the basis of gas-phase PARTICLES dispersion of an odor source. However, the 1.Volatile Particles interpretation of these experiments isopen to doubt, and it is probable that the effects Liquid or even solid aerosols may be suffi- are a result of fortuitous fluctuations in emis- ciently volatile that their vaporizationon en- sion. For example, Walter and Amberg have tering the nasal cavity produces enoughgas- found that concentrations of hydrogen sulfide eous material to be detected by smell. Such in a kraft paper pulp mill recovery furnace aerosols may be relatively pure substances, o. can vary from 100 ppm to as much as 1,000 such as particles of camphor, or theymay be ppm. Such wide variations in emission may mixtures which release volatile components. help to explain the discrepancy, reported by The retention of the odorous properties of Wohlers 3 for a kraft mill, between the odor volatile aerosols will, of course, dependon the intensities observed and those predicted from prevailing temperature and on the length odor threshold concentrations and dilutions of time they are dispersed in air. In a cold calculated by Sutton's formula' The likeli- atmosphere, the relatively greater tempera- hood that errors in calculations of the atmos- ture rise accompanying inhalation will accel- pheric dispersal of true gasesare compara- erate the production of gaseous odorant. tively small is supported by experiments with 2.Desorption of Odorous Matter by gas tracers like sulfur hexafluoride (SF6). Particles Collins et a/.19 and Turk et a/.11 have shown Goetz 22 has treated the kinetics of the in- agreement between calculated and observed teraction between gas molecules and the sur- concentrations of a tracer gas at distancesup face of airborne particles. His theoretical to about three miles from the emission point considerations were directed to the question to be within about 25 percent. It is true that of transfer of toxicants by particles, butare olfactory sensation is responsive toconcen- also applicable to odors. Even if a givenaero- trations that may be present for only brief sol is intrinsically odorless, it could actas an intervals, whereas dispersioncalculations odor intensifier if: 1. the sorptive capacity of refer to time averages for intervals of about the aerosol particles for the odorantwere one-half hour, and the tracer gas studies cited smaller than the affinity of the odorant for used 20-minute integrated samples. Some of the nasal receptor and at the same time, 2. the discrepancy between results of odormeas- the sorptive capacity of the aerosol particles urements on the one hand, and results from were large enough to produce an accumula- calculations or tracer gas testson the other, tion of odorant on the particle surface. Such may therefore be accounted for by the peak- aerosol particles would concentrate odorous to-mean ratios that result from the effects of molecules on their surfaces, but the odorous turbulence and eddies in the air stream. matter would be transferred to olfactory There are no published dataon the minimum receptors when the aerosol entered the nasal time duration required for odor detectionor cavity. The odorous matter would then be odor nuisance responses. Efforts by Turk and present at the receptor sites in concentrations coworkers to determine the ratio of "instan- higher than in the absence of the aerosol. The taneous" (one second) to average (20 min- resulting effect would be synergistic. See ute) concentrations of tracergas failed to Chapter 10-C-3 for a discussion ofsyner- show significantly high values, possiblybe- gistic effects of particles and irritants. These cause such occurrences are rare and escaped synergistic effects may be analogous topar- the sampling grid,. In any event, thepeak-to- ticle-odorant synergism. If an odorant is mean ratios would have to be in the 1,000 to more strongly adsorbed by the aerosol parti- 10,000-fold range to explain observed discrep- cles than by the olfactory receptors, transfer ancies, and we have no data thatare based on of the odorant to the receptors would be im- - meteorological factors alone to support such peded and the particles would actually at- extreme values. tenuate the odor. 115 3.Odorous Particles Table 8-1.MOST FREQUENTLY REPORTED ODORS No study has ever rigorously defined the Number upper limit of particle size for airborne odor- Source of odor reported ous matter. Particles up to about 8 or 10 X Animal odors: Meat packing and rendering plants 12 10-4ILin diameter are considered to be mole- Fish oil odors from manufacturing cules that can exist in equilibrium with a plants 5 k: solid or liquid phase from which they escape Poultry ranches and proce.cing 4 by vaporization. The vapor pressure de- Odors from combustion processes: creases :Is the molecular weight increases, Gasoline and diesel engine exhaust 10 and particles above about 10-sILdo not gener- Coke-oven and coalgas odors (steel mills) 8 ally exist in any significant concentration in Maladjusted heating systems 3 equilibrium with a bulk phase; hence we do Odors from food processes: not consider them to be "vapors." Nonethe- Coffee roasting 8 less, it is possible that odorant properties do Restaurant odors 4 not disappear when particle sizes exceed Bakeries 3 those of vapor molecules. Our knowledge Paint and related industries: about particles in the size range of 1 to 5 X Manufacturing of paint, lacquer, and 10-aµ (up to about the size of small viruses) varnish 8 Paint spraying 4 is relatively meager, and we do not knOw Commercial solvents 3 whether or not they can be odorous, nor what General chemical odors the effect of an electrical charge on their Hydrogen Sulfide odorous properties might. be. Larger parti- Sulfur Dioxide 4 cles may also be intrinsically odorous, al- Ammonia 3 though their more significant role may be to General industrial odors contribute to odor by absorbing and desorb- Burning rubber from smelting and debonding 5 ing odorous gases and vapors. Odors from dry-cleaning shops 5 Fertilizer plants 4 D. COMMON ODOR PROBLEMS. Asphalt odorsroofing and street Kerka and Kaiser ls surveyed State and 4 Asphalt odorsmanufacturing 3 local air pollution control personnel and com- Plastic manufacturing 3 piled the list of most frequently reported Foundry odors odors shown in Table 8-1. Core-oven odors 4 Of the 35 listings in Table 8-1, nine are Heat treating, oil quenching, and either known to be or suspected to be particu- pickling 3 late-borne. These nine include gisoline- and Smelting e- 2 diesel-engine exhaust, coffee roasting, restau- Odors from combustible waste: Home incinerators and backyard rant odors, paint spraying, roofing and street trash fires 4 paving, asphalt manufacturing, home incin- City incinerators burning garbage 3 erators and backyard trash fires, city inciner- Open-dump fires 2 ator burning garbage, and open-dump fires. Refinery odors: Mercaptans 3 E. SUMMARY . Crude oil and gasoline odors 3 Sulfur 1 Airborne particulate matter, as an air pol- Odors from decomposition of waste: lutant category, is normally not considered Putrefaction and oxidationorganic as a source of odor stimulation. However, acids 3 there is evidence that some particulates hav- Organic nitrogen compoundsdecom- position of protein ing volatile components can produce an odor 2 Decomposition of lignite (plant cells) 1 response in human receptors. Sewage odors: Further, by a suggested mechanism of ad- City sewers carrying industrial waste 3 sorption and subsequent desorption, an odor- Sewage treatment plants 2 ant may be transferred by a particulate sub- Probably related to meat processing plants.

107 strate. When one examines the various types 4. Quebedeaux, W. A. "New Applications for Indus- of odor sources which result in public aware- trial Odor Control." Air Repair, Vol. 4, pp. 141- ness of an undesirable situation, a significant 142, 170-171, 1954. number of these listings are either known to 5. Turk, A. and Bownes, K. "Inadequate Stimula- tion of Olfaction." Science, Vol. 114, pp. 234-236, be or suspected to be particulate-borne. A 1951. survey of State and local air pollution control 6. Turk, A., Kakis, F., and Morrow, J. "The Ad- officials revealed that approximately one- sorbent Odor," Preprint. (Presented at the Amer- fourth of the most frequently reported odors ican Chemical Society meeting, New York, Sept. are those which are known to be, or are sus- 1960.) pected to be, associated with particulate air 7. Walther, J. E. and Amberg, H. R. "Continuous pollution. The sources of these odorous parti- Monitoring of Kraft Mill Stack Gases with a Process Gas Chromatograph." Tappi, Vol 50, cles are diverse, including diesel- and gaso- pp. 19-23, 1967. line-engine exhaust, coffee-roasting opera- 8. Wohlers, H. C. "Odor Intensity and Odor Travel tions, paint spraying, street paving, and the from Industrial Sources." Intern. J. Air Water burning of trash. Despite the absence ofan Pollution, Vol: 7, pp. 71-78, 1963. exact mechanism to explain the association 9. Sutton, 0. G. "The Theoretical Distribution of of odor with particulates, their intimate in- Airborne Pollution from ;.Factory Chimneys." volvement in multiple categories of citizen Quart. J. Roy. Meteorol. Soc., Vol. 73, pp. 426- nuisance complaints cannot be ignored. 436, 1947. 10. Collins, G. F., Barlett, F. E., Turk, A., Edmonds, F.REFERENCES S. M. and Mark, H. "A Preliminary Evaluation of Gas Air Tracers." J. Air Pollution Control 1. Roderick, W. R. "Current Ideas on the Chemical Assoc., Vol. 15, pp. 109-112, 1965. Basis of Olfaction." J. Chem. Educ., Vol. 43, pp. 11. Turk, A., Edmonds, S. M., Mark H. L., and Col- 510-520, 1966. lins, G. F. "Sulfur Hexafluoride as a Gas-Air 2. Rossano, A. T. and Ott, R. R. "The Relationship Tracer." Environ. Sci. Technol., Vol. 2, pp. 44- Between Odor and Particulate Matter in. Diesel Exhaust." Preprint. (Presented at the Annual 45, 1968. Meeting of the Pacific Northwest International 12. Goetz, A. "On the Nature of the Synergistic Section, Air Pollution Control Association, Port- Action of Aerosols." Intern. J. Air Water Pollu- land, Oregon, November 5-6, 1964.) tion, Vol. 4, pp. 168-184, 1961. 3. Linnel, R. H. and Scott, W. E. "Diesel Exhaust 13. Kerka, W. F. and Kaiser, E. R. "An Evaluation Composition and Odor Studies." J. Air Pollution of Environmental Odors." J. Air Pollution Con- Control Assoc., Vol. 12, pp. 510-515, 1362. trol Assoc., Vol. 7, pp. 297-301, 1958.

108 17 Chapter 9

THE RESPIRATORY SYSTEM: _DEPOSITION, RETENTION, AND CLEARANCE OF PARTICULATE MATTER

-118 Table of Contents Pogo A. INTRODUCTION 111 B. ANATOMY OF THE HUMAN RESPIRATORY TRACT 111 C. FACTORS AFFECTING THE DEPOSITION AND RETENTION OF PARTICULATE MATTER IN THE RESPIRATORY SYSTEM 112 1. Physical-Mathematical Treatments 112 a. Deposition Mechanisms 112 b. Aerodynamic Factors 113 c. The Models 114 2. Experimental Studies of Factors Affecting Depositim. sui Retention .... 116 a. Total Deposition in the Respiratory Tract 117 (1) Effect of Particle Size 117 (2) Physiological Parameters 117 b. Regional Deposition 118 (1) Nasal Fractionation 118 (2) Lung Deposition 118 (3) Comparative Human and Animal Retention 119 3. Conclusions Reached about Alveolar Deposition 119 D. FACTORS AFFECTiNG THE CLEARANCE OF PARTICULATE MATTER FROM THE RESPIRATORY SYSTEM 119 1. Clearance Model 120 2. Clearance from the Tracheobronchial System 121 3. Clearance from the Alveolar Surface 122 E. SUMMARY 123 F. REFERENCES 123 List of Figures Figure 9-1 The Major Anatomical Features of the Human Respiratory System 112 9-2 The Terminal Bronchial and Alveolar Structure of the Human Lung 112 9-3Calculated Fraction of Particles Deposited in the Respiratory Tract as a Function of Particle Radius 114 9-4Fraction of Particles Deposited in the Three Respiratory Tract Com- partments as a Function of Particle Diameter, 115 9-5 Data from Figure 9-4 for the NasopharyngeAl Compartment Plotted as a Log-probability Function (Minute Volume: 20 limin) 116 9-6 Data from Figure 9-4 for the Pulmonary Compartment Plottedas a Log-probability Function (Minute Volume: 20 limin) 116 9-7Schematic Portrayal of Dust Deposition Sites and Clearance Proc- esses 120 List of Tables Table 9-1Respiratory Airflow Patterns for a Group of Healthy Young Men.... 113 :;.. 110 r.

Chapter 9 THE RESPIRATORY SYSTEM: DEPOSITION, RETENTION, AND CLEARANCE OF PARTICULATE MATTER

A.INTRODUCTION practical importance, since the Stokes diameter may readily be determined under field In urban communities, exposure to atmos- conditions. pheric pollutants may constitute a health The anatomy of the respiratory system hazard that is the most serious single conse- plays an important part in determining the quence of air pollution. Chapters 10 and 11 effects of inhaled particles, and a very short discuss the effects of particulate pollutants description of this anatomy is provided. Sev- on health in terms of toxicological and epide- eral extensive presentations of morphological miological studies. Pollutants are likely to studies are.available,5. e and Davies' gives a enter the human body mainly via the respira- formalized concept of the anatomy of the tory system; other routes of entry_are of human respiratoiy tract. minor importance. Damage to the respiratory organs may follow directly, or the pollutant B. ANATOMY OF THE HUMAN may be transported by some mechanism to a RESPIRATORY. TRACT remote susceptible organ. It is apparent that The respiratory system is usefully broken a study of the effect on health of particulate down into three main sections: atmospheric pollutants requires an understanding of the mechanisms and efficiencies 1. the nasopharyngeal structure; of deposition of particles in the respiratory 2. the tracheobronchial system; and system, and of the subsequent retention with- 3. the p ulmonary structure, within in, and clearance from. the system, as well which oxygen and carbon dioxide are as its secondary relocation to other sites in exchanged between respired air and the body. This chapter provides a brief intro- blood. duction-to the physics and physiology of de- Figure 9-1 shows the location of these fea- position, retention, and clearance in the res- tures. The nasal passages lead, via the naso- piratory system. More complete descriptions pharyngeal structure and the larnyx, to the may be found in several reviews." trachea and the bronchi, which are made up Experimental studies of the several fac- of 23 generations of dichotomous branching tors involved in deposition, retention, and tubes terminating in the alveolar (air) sacs. clearance processes have been backed up by Figure 9-2 is a schematic representation in theoretical treatments and, in the discussion greaterdetail,of the terminal bronchiole and which follows, descriptions of these theoreti- pulmonary structure. cal models precede those of experimental Estimates of numbers of alveoli differ work. One of the latest theoretical models is somewhat from one experimenter to another: that developed by the Task Group on Lung a recent suggestion 8 is that there are 300 mil- Dynamics for Cominittee II of .the Interna- lion, together with 14 million alveolar duets. tional Radiological Pkotection Commission.* The alveoli are probably between 150 and The Task Group's report establishes the use- 4001& hi diameter, so that the total alveolar fulness of the Stokes (mass median) diam- surface varies between about 30 m2 and 80 eter (cf. Chapter 1-A) of a particle as a m2. The increasing total cross-sectional area measure of deposition probability. This is of with progression down the respiratory tract PHARYNX NASAL CAVITY TERMINAL ORAL BRONCHIOLE CAVITY

LARYNX Al TRACHEA

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RIGHT LUNG LEFT LUNG

FIGURE 9-1.The Major Anatomical Features of the Human Respiratory System. (The diagram shows the major divisions of the human respiritory tract into nasopharyngeal, tracheobronchial, and pulmonary compartments.) FIGURE9-2. The Terminal Bronchial and Alveolar leads to a marked decrease in the velocity of Structure of the Human Lung.(The diagram shows the pulmonary structure of the respiratory air movement with depth. tract.) The nasopharyngeal and tracheobronchial structures possess ciliated epithelium covered treatments use information on the anatomical with mucus arising from goblet cells and structure and airflow rates in the respiratory secretory glands. These structures also make tract, together with knowledge of the physi- up the anatomical "dead space," since oxygen cal factors influencing the deposition of par- exchange between the blood and air does not. ticles. The deposition mechanisms will be occur here. If the volunie of this dead space considered first; aerodynamic factorscon- isVd,the lungs must draw in a volume V in nected with airflow and gas mixing in the order to obtain a volume VVd of fresh air, respiratory system will then be mentioned which is called the tidal volume. The surface before proceeding to a discussion of the three of the pulmonary 'structure consists ofnon- main models which have been developed. ciliated moist epithelium that, although de- void of the secretory element found in the a. Deposition Mechanisms tracheobronchial tree, is covered bya sur- Three mechanism are of importance in the face-active material, without which alveoli deposition of particulate matter in the respi- would totally collapse (atelectasis) at the end ratory tractinertial impaction, gravitation: of respiration. al settling (sedimentation), and diffusion C.FACTORS AFFECTING THE (Brownian motion). The relative significance DEPOSITION AND RETENTION OF of these deposition mechanisms varies with PARTICULATE MATTER IN THE anatomical and physiological factors, with, RESPIRATORY SYSTEM the nature of the airflow, and with the characteristics of the aerosol such as particle 1.Physical-Mathematical Treatments shape and density. Thetheoreticalphysical-mathematical Particles in an airstream impinge ontoa 112 121 S

surface when the inertia of the particle is between the two phases. A study of the res- great enough to overcome the resistive forces piratory airflow patterns of healthy young of the medium and intercept the surface of men at rest and under a wide range of work the obstacle. If gravity is neglected, the path loads Was made by Silverman et al. The max- of the particle is determined by the air veloci- imum inspiratory flow rate increased from a ty, the mass and air resistance of the par- mean value of 40 1/min in sedentary subjects ticle, and size and shape of the obstacle. In- to 100 1/min at an exercise level of 622 kg- ertial impaction is therefore of greatest im- m/min and to 286 1/min at an exercise level portance in the deposition of large particles of 1660 kg-m/min. The corresponding values of high density, and at points in the respira- for maximum expiratory flow rates were 32, tory system where the direction of flow 107, and 322 1/min. The collected results are changes at branching points in the airways. shown in Table 9-1. The size of the particle as well as its densi- Changes in flow rate resulting from physi- ty are singificant factors in determining the cal activity have a profound effect on particle importance of deposition by gravitational set- deposition in the respiratory system; this ef- tling. The terminal velocities (settling veloci- fect in turn depends upon the aerodynamic ties) of spheres of unit density in air for size of the particulate material inhaled. It has 10-A, 1-p., and 0.1-s particles are 2.9 x 10-3 been demonstrated by:./Amdur, Silverman, cm/sec, 3.5 x 10-3 cm/sec, and 8.6 x 10-3 cm/ and Drinker " that the inhalation of irritant sec respectively. Density also plays a part particulate material, such as sulfuric acid since the sedmimentation behavior of a 0.5- mist, can decrease the maximum inspiratory A particle of density 10g/cm3 would be and expiratory flow rate in human subjects. equivalent to that of a unit density particle of Such alterations produced by irritant par- 1.5-s diameter. Hence, gravitational settling is most important in the depositon of large Table 9-I. -RESPIRATORY AIRFLOW PATTERNS particles or of high-density particles such as FOR A GROUP OF HEALTHY YOUNG MEN." dusts of heavy metals. Irregularly shaped particles will have an aerodynamic size less Exercise Inspiratoiy flow Expiratory flow than the size predicted on the basis. of the level rate 1/min (max) rate 1/min (max) measured geometric diameter. Sedentary 40 32 The third main mechanism active in bring- 622 kg-m/min 100 107 ing about deposition of particles in the res- 1660 kg-m/min 286 322 piratory tract is Brownian movement or diffusion; it is the result of bombardment of tho particles by air molecules which are in rapid, tides could also affect deposition patterns of random, thermal motion. Diffusion is negli- particulate matter in general, and may re- gible for large particles (say above 0.5-A present the physiological defense response of diameter), while it may be the major mecha- the body. . nism for the deposition of small particles Another factor to be considered in the dep- (below 0.1,u) in the lower pulmonary tract, osition of particulate matter in the lung is where airflow rates are lower and the dis- the role of mixing of intrapulmonary gas tances to the walls are less. flow. A study of this factor has been made by Altshuler and co-workers " using 0.4-s b. Aerodynamic Factors partides suspended in air. From the meas- Two aerodynamic factors, namely, flow ured wash-in and wash-out rates (after re- rates and gas mixing, are incorporated in turn to particle-free air), the authors were the models of the respiratory system. able to calculate the volume of new air which During the respiratory cycle, the actual mixed with the residual air. Their data airflow rate varies from zero up to a maxi- showed that at a tidal volume of 500 ml, not mum value and then back down to zero. Usu- more than 11 percent to 27 percent of new air ally the expiratory phase is longer than the in each successive breath actually mixed with inspiratory phase and there may be pauses the residual air. It follows that nondiffusible

113 122 particles (above 0.5 p) will tend to penetrate only to the depth of the new air, while smaller particles will have great enough diffusion 0 velocities to move independently into the static: air in the lung, in the sameway that us DEPOSITION IN RESPIRATORY gas molecules do. SYSTEM 0 c. The Models 0.0. For the present purposes, the most impor- 020. tant model is that of the Task Group on Lung' go Dynamics! However, two earlier studies, as those of Findeisen '= and Landahl," U. are of 0.2 DEPOSITION IN ALVEOLAR significance, since they were both considered REGION ONLY as a basis for the Task Group model. The 0.1 Task Group finally selected Findeisen'sana- C.. 10'2 10 tomical model, since it appeared that the RADIUS, rather more sophisticatedtreatment of Landahl gave no better estimates of deposition values. Further, the cumulative volume FIGURE 9-3. Calculated Fraction of ParticlesDe- down to the end of the terminal bronchioles ' posited in the Respiratory Tractas a Function of Particle Radius." (The figure represents.the in the Findeisen model is more in keeping calculated efficiencies of deposition of particles of with the anatomical dead spaceas determined various sizes, in the tracheobronchiat andalveolar by physiological measurements. regions of the respiratory system, and showsthe Findeisen '= predicted the percentage of size for minimum efficiency.) deposition and the site of deposition ofpar ticles of various zizes in the respiratory tract. of the problem of particle deposition inthe He estimated there would be a critical parti- respiratory tract, but included the mouthand cle size of about 0.3-1L to 0.4-s radius for pharynx in his anatomical model. Heem- which a minimal amount of 34 percent would ployed several tidal volumes and breathing frequencies in his calculations, but in all be deposited. This deposition wouldoccur cases predominantly in the terminal airways and assumed a constant flow for both the inspira- alveoli, thus suggesting that particles of this tory and expiratory phases. The calculations size should not be dismissed as toxicologically yielded deposition values for both phases,and unimportant. Findeisen also estimated that took into account the progressively smaller the percentage deposition of 0.3-s radius fraction of each tidal volume whichpene- par- trated to the various depths. Deposition ticles would be 68 percent as muchas that of in 1--A radius. particles. His calculated deposi- various regions for spheres of unitdensity in tions are shown in Figure 9-3. Experimental the size range 20Ato 0.2Awas predicted to work on deposition of particles smaller than fall to a minimum at the size where thepre- dominant force bringing about deposition 1--A diameter have borne out Findeisen'spre- is dictions. shifting from gravitational settlingto diffusion. An increase was found in retention Findeisen's concepts of the anatomyof the with larger tidal volumes. pulmonary tract have been criticized by Landahl 15 also made a separate considera- Weibel. Findeisen assumed equal and con- tion of deposition in the nasal stant flow rates for inspiration and expira- passages. Ear- lier studies did not take into accountimpac- tion; a situation which does not prevail dur- tion of particles on nasal hairs, ing the respiratory cycle. Furthermore, this or deposition by inertial forces as the airflow changesdi- simple respiratory pattern does not take into rection, or sedimentation within the nasal account the unique distribution of air in the chamber. Assuming a flow rate of 18 1/min, lungs, or the factors of intrapulmonary mix- about 75 percent of 10-14 particles would ing of tidal and residual air in the lungs. be retained in the nose. Correspondingvalues Landahl 15 made a similar theoretical study would be about 50 percent fore.5;-/Lparticles 114 123 and 10 percent for 1-IL particles. Landahl measurement of one diameter permits the calculated that at flow rates greater than 18 calculatidn of the other, and both can beex- 1/min, essentially 100 percent of the particles pressed as aerodynamic (Stokes) equivalent above 10 IL would be retained in thenose and diameters.The Task Group used calcula- that there also would be substantial retention tions basically similar to those of Findeisen of 2-1& to 5-IL particles. Nasal deposition is to estimate the deposition in the threeres- negligible for particles below 1IL in diameter. piratory compartments. When the massme- It follows that the estimated pulmonary dep- dian aerodynamic diameters of 0.01IL to 100 IL osition values of Findeisen would have to be of various distributions, as represented by revised downward for the large particles. different geometric standard deviations,were The Task Group on Lung Dynamics used plotted against the estimated mass deposi- the conventional division of the respiratory tion of particles occurring in each respira- tract into three compartments, and made tory compartment, surprisingly little vari- three fundamental assumptions in the de- ability was seen with0g ranging from 1.2 velopment of their model. These were: to 4.5. The results of these calculations are 1. The log-normal (Chapter 1-B) fre- shown in Figure 9-4; the curves indicatea quency distribution is generally ap- relationship between the mass median aero- plicable to particle sizes in the atmos- dynamic diameter and the gravimetric frac- phere. It should be noted that this as- tion of the inhaled particles which would be sumption is by no means universally deposited in each anatomical compartment. accepted. Within these limits (0.01IL to 100 K), the 2. The physical activity of the individual mass median aerodynamic diameter served affects deposition primarily by its action on ventilation, since physiological adjuitment to the demands of increased minute ventilation is to increase tidal volume more than respiratory frequency. In terms of producing the greatest change in deposition throughout the respiratory tract, the effect of an increase in volume ata constant respiratory frequency was considered.(Afrequencyof15 breaths per minute was used together with tidal volumes of 750, 1450, and 2150 'cm3 (BTPS) ; the lowest tidal volume is considered representative of a mild-to-moderate activity state.) 3. The aerodynamic properties of the particle, the physiology of respiration, and the anatomy of the respiratory tract provide a basis for a meaningful and reliable deposition model. The Task Group's aim was to amalgamate size-deposition relationships intoa general- 110.2 101 10° 101 102 ized form which would directly permit the MASS MEDIAN DIAMETER, 1,1 prophetic use of dust-sampling information. By conventional sampling methods, the count FIGURE 9-4. Fraction of Particles Deposited in the median diameter or the mass median diam- Three Respiratory Tract Compartnients as a Func- eter is Obtainable along with the geometric tion of Particle Diameter.' (This figure shows the . deposition efficiencies calculated by the Task Group standard deviation, ag (Chapter 1-A). The on Lung Dynamics.) to characterize the deposition probabilities of as constant at approximately 8 percent of the entire particle size distribution from the inspired particulate matter. which it emerged. Other parametric' func- The results of the Task Force's calculations of the particle distribution failed to tions suggest the type of atmospheric sam- produce such simple cohesive relationships. pling data that will be most meaningful in The effect of the varying tidal volumes is the correlation of atmospheric particle con- shown in the original report (Figure 12, Ref- centrations and human health. In particular, erence 4), but it is possible, for practical pur- the insensitivity of the model to aerodynamic poses, to use a mean curve for 1450 ml to size distribution leads the Task Force to pro- represent all three respiration states. This pose the concept of "respirable" dust sam- implies that the minute volume will control ples, in which the samplersare designed and the total amount of particulate material de- calibrated to provide data from which one posited but will not ordinarily have much can determine the mass median diameter in effect on the percentage deposition. aerodynamicterms.Such considerations The final step was to plot the combination have a special significance in connection with of mean distribution versus mean respira- particles, such as asbestos, which possess an tory performance curves on log-probability abnormal deposition behavior. paper, a manipulation suggested by the sig- mold shape of the nasopharyngeal and pul- 2.Experimental Studies of Factors monary deposition curves. The results are Affecting Deposition and Retention shown in Figure 9-5 and Figure 9-6. The Experimental studies of the deposition of deposition in the tracheobronchial compart- inhaled particulate material may be divided ment is considered, for practical purposes, into two broad categories. The first group

102 1 IIIIII I

101

10-1

10.2 j 1 301 1 5iZ1 90 99 99.9 1 10 30 50 7090 99 99.9 DEPOSITION, % DEPOSITION, 96'.

FIGURE 9-5. Data from Figure 9-4 for the Naso- FIGURE 9-6. Data from Figure 9-4 for the Pulmo- pharyngeal Compartment Plotted as a Log-proba- nary Compartment Plotted as a Log-probability bility Function.(Minute volume:20 1 /min).. Function' (Minute Volume: 20 1/min). (This fig- (The figure shows that there is a roughly linear ure shows that there is a roughly inverse linear relationship between deposition efficiency and the relationship between deposition efficiency and the logarithm of the particle size.) logarithm of particle size.)

116 rwa

deals with the measurement of total deposi- the pulmonary air spaces is close to 100 per- tion in the respiratory tract, and the second cent. Direct measuremmt of the particulate group is concerned with regional deposition matter concentration in samples of alveolar within the various areas of the respiratory air showed an efficiency of removal ofessen- tract. tially 100 percent down to about 0.5p and a. Total Deposition in the Respiratory Tract better than 80 percent for particles well be- Experimental studies of depositionwere low 0.1 p." first made by Lehmann etal.," Saito," A hygroscopic particle may collect suffi- Owens," Baumberger,19 and Sayers et al." cient water to increase its size significantly Drinker et al.," measured respiratory deposi- over that in the dry state. Dautrebande and tion in man with simultaneous recording of Walkenhorst 26 have therefore compared the respiratory frequency and minute volume. deposition of sodium chloride with that of The concentration of particulate matter was coal dust. Using the dry size of the salt par- measured in the chamber, from which air ticles, deposition curves different from those was inhaled, and in the exhaled air. An aver- for coal dust were obtained, but on correcting age retention value of 55 percent at a fre- (by a factor of seven) to account for the quency cf six to 18 respirations per minute growth of salt to liquid droplets in the res- was found. piratory tract, the curves were quite similar (1) Effect of Particle Size.The first sys- for the two particles. This result is of con- tematic study of the influence of particle size siderable practical significance, as it means on the percentage deposition of inhaled dust that hygroscopic particulate air pollutants was made in 1940 by Van Wijk and Patter- will be deposited to a higher degree than son." The subjects. at rest, inspired min- mineral particles of an equal size. .The Task eral dust particles from the air of South Af- Force Report4 gives equations which may rican gold mines. Percentage depositionap- be applied to correct for the effect of hygro- proached 100 percent above 5p and had de- scopicity on deposition. creased to about 25 percent at 0.25p, to the (2) Physiological parameters.In Brown's limit of the measuring technique. experiments,". 24 the effect of varying res- Brown 21.24 made a series of tests on hu- piratory frequency, tidal volume, and minute man subjects in which he found that the per- volume was determined by making measure- centage deposition is directly proportional ments on subjects breathing at rest, under to the particle size and to the density of the various work loads on a bicycle ergometer, suspended material. (Size refers here to the and breathing air containing added CO:. The physical dimensions of aggregates ofpar- conclusions of this work were: ticles rather than to unitary particles.) 1. Percentage depositionisinversely More sophisticated experiments by Alt- proportional to respiratory rate for shuler et at." have used a homogeneousaero- sol of triphenyl phosphate, with particle rates below 20 per minute and an sizes in the range 0.14p. to 3.2 p to study increase in frequency above 30 per deposition in human subjects. It was found minute causes no further change in that deposition was dependent on particle percentage deposition; size and that the minima deposition diam- 2. Percentage depositionisinversely eter was 0.4 A, which is in reasonable accord proportional to the minute volume; with the prediction made by Findeisen (0.6 and It to 0.8 p) 20 years earlier. 3. Percentage deposition is unaffected The deposition of coal dust in human sub- by tidal volume, vital capacity,or jects has been shown 26 to rise froma mini- relative humidity of the inspired air. mum efficiency of about 30 percent at 0.5 The results are essentially in agreement to almost 60 percent at 0.1p (mass median with the predictions of Findeisen and Lan- diameter).Such an overall efficiency sug- dahl (although no effect of tidal volumeon gests that the absolute efficiency of deposi- deposition was observed). tion of the particles smaller than 0.1p in In general agreement with Brown's result for respiratory rate, Altshuler et al.25 found using a test dust of unspecified size, found in their experiments that slower, deepera median nasal deposition of 46 percent in breathinggave greaterdepositionthan 185 normal subjects and 27 percent in 241 faster, shallow breathing. It is also shown silicotics. Dust-laden air was blown through that, in agreement with prediction, the dif- the nose and out through a tube in the mouth. ferences due to respiratory frequency are Tourangeau and Drinker 32 Wind deposition greater for 1.6-ft particles than for 0.14-p efficiencies of 10 percent to 25 percent with particles. For the 1.6-k& particles, impaction airflow rates through the nose of 4 to 12 and settling are the dominant mechanisms liters per minute. Their dust was calcium "Thdeposition,and the number settling varies carbonate of a size comparable to the silica as ihe first power of time. With the 0.14-p, particles found in silicotic lungs.Reversal partilis, Brownian motion is the dominantof the direction of flow did not alter the deposition mechanism, and the number set- values. tling varies as the square root of time. The most extensive experimental studies Experiments with stearic acid particles 28 of nasal penetration have been made by Lan- have revealed an interesting phenomenon of dahl's group.". 34 The results, especially for minimal deposition at normal breathing fre- corn oil particles, confirm theoretical predic- quencies of 15 to 20 breaths per minute and tions," and nasal deposition is found experi- an increase when the frequencies were either mentally to have a strong dependence on air- higher or lower than this. A range of res- flow rate. piratory rates from less than 5 Mier minute (2) Lung Deposition.Wilson and La to more than 35 per minute was used, and Mer 26 used an aerosol of glycerol containing particle diameters lay between 1p and 5 p. Na24C1 as a tracer in seven normal subjects On the other hand, Morrow and Gibb 29 find who breathed through the mouth at varying that the deposition of 0.04-ft sodium chloride frequencies. Particle sizes were in the range particles in dogs and human subjects de- of 0.2. IA to 2.5 II.External chest counts en- creases with an increase in breathing fre- abled estimates of lung burden to. be made, quency. The deposition percentages them- and the pulmonary deposition curve showed selves (66.5 percent in dogs, 63.4 percent in a maximum of about 80 percent for particles man) are close to those predicted by Fin- of about 1.6-p diameter. A second peak at deisen. An increase in tidal volume increased 0.4 k& was interpreted in terms' of the differ- the deposition in these experiments in dis- ing optimum sizes for deposition in the finest tinction to the absence of a tidal volume ef- airways and in the pulmonary air spaces; fect found by Brown. deposition in these two areas was not dis- There appears to be a direct relationship tinguished by the method employed. between percentage deposition and holding Indirect estimates of upper respiratory, time in the lungs for particles of 0.55IA di- alveolar, and total deposition in human sub- ameter." jects were made by Brown et at," usinga b. Regional Deposition technique for fractionating the exhaled air. In each successive portion, the CO2 content The experimental study of regional depo- was measured together with the particle sition of particles is more complex than is count and thus the amount of lung air in the determination of overall total deposition each portion of the sample could be esti- in the respiratory tract. Various specialized mated.Equal removal efficiencies in both techniques such as the inhalation of radio- directions were assumed, and a series ofex- active particles followed by external count- pressions was developed for calculating total, ing over specified portions of the chest,oralveolar, and upper respiratory deposition. radioautography of the lungs, have been em- The median particle size of the china clay ployed. The technique of fractionatingex- test dust ranged from 0.24It to above 5 14 haled air and counting the particles in each and the total retention decreased systemati- fraction has also been used. cally from 90 percent or more for particles (1) Nasal Fractionation. Lehmann," 5 p and greater, down to 25 percent to 30 118 percent for 0.25-p particles. Tracheobron- 3. The percentage of particle deposition chial retention also decreased systematically for sizes less than 0.1 p is just as with particle size but reached zero at a finite great as for sizes more than 1 p, (Fig- size above 1 p. Alveolar retention, calculated ure 9-3). This last conclusion is not as the percentage of the number of particles always given enough weight, even reaching the alveoli, remained between 90 though its prediction by Findtsen " percent and 100 percent for all sizes down to has been adequately confirmed ex- about 1 p.; below that, it decreased in pro- perimentally.20. 29 portion to total retention. The calculated On the other hand, the importance of the curve for alveolar deposition showed an opti- second conclusion above should not be over- mum size at 1 p. emphasized, as it refers only to the proba- (3) Comparative Human and Animal Re- bility of deposition.If their number, and tention.A technique essentially similar totherefore the mass deposited, is relatively that used by Brown in his experiments on great (as may well be for aged aerosols), humansubjects(see Section C- 2 -a -(2) then particles in the 0.1-p. to 0.5-µ size re- above) has been employed by Palm, McNer- gion may be as important as smaller and ney, and Hatch'? for studies on guinea pigs larger particles in provoking toxic response. and monkeys.This provides a valuable This is also important when considering par- chance to compare results of experiments on ticles containing absorbed material. laboratory animals and man. The test dusts included china clay, carbon, antimony tri- D. FACTORS AFFECTING THE oxide, and bacillus subtilis var. niger. The CLEARANCE OF PARTICULATE overall pattern of the results was similar in MATTER FROM THE RESPIRATORY the experimental animals and in man. The SYSTEM actual deposition and retention valueswere A well-known response of a living orga- very close for the monkey and for man. For nism to foreign matter is its attempt to rid the guinea pig, total retention was close to itself of, or in some way inactivate, the un- 100 percent for 3-p. particles and fellsys- wanted material. The overall effectiveness tematically with decreasing particle size. In of clearance mechanisms in the lung is well comparison with ma,n, the total retention illustrated by the finding that the actual was higher, especially in the lower size range. amount of mineral dust found in the lungs Alveolar retention was essentially thesame of miners or city dwellers at autopsy is only in both species, and it is the tracheobron- a minor fraction of the total dust that must chial retention which higher in the guinea have been deposited there during their lives. pig than in man. Although alveolar deposi- The clearance of certain particles may be tion in the guinea pig was much lower for very slow. The rate is dependent upon size, 1.5-a particles than in man, because of the site of deposition, and chemical constitution. removal of these particles in the tracheo- Relative to other factors, the importance bronchial tract, the optimum size for alveolar of removal from the respiratory system of deposition was similar in both species. trapped particulate materials depends on the rate at which the material elicits a patho- .3.Conclusions Reached about Alveolar logical or physiological response. The effect Deposition of an irritant substance which produces a Threeimportantconclusionsmay berapid response may depend more on the reenlied about the effect of particle size on amount of initial trapping than on the rate alveolar deposition: of clearance. On the other hand, materials such as carcinogens, which may produce a 1. There is a maximum efficiency of harmful effect only after long periods of ex- deposition at a size between about 1 posure, may exhibit activity only if the rela- and 2 p; tive rates of clearance and deposition are 2. There is minimum efficiency for a such that a sufficient concentration of mate- sizeof.around 0.5 p; and rial remains in the body long enough to cause 12& 119 la) NASOPHARYNGEAL (b) COMPARTMENT

,(c) GASTRO- BLOOD TRACHEOBRONCHIAL COMPARTMENT INTESTINAL TRACT

/ D5 el `milimmul PULMONARY COMPARTMENT (I) (hl 1

LYMPH

FIGURE9-7. Schematic Portrayal of Dust Deposition Sitesand Clearance Processes. (This diagram illustrates the various deposition sites and clearancemechanisms used in the model of the lung developed by the Task Group on Lung Dynamics, and describedin the text.)

pathological change. In sucha case, the late matter, as well as its deposition, andthe amount of initial' deposition will be of rela- model they developed providesa convenient tively minor importance. starting point for a discussion of experimen- Different clearance mechanisms operate in tal work on clearance. the different portions of the respiratorytract, Figure 9-7 presents a schematic diagram so that the rate of clearance of a particle of all deposition sites and clearanceproc- will depend not onlyon its physical and esses. The three conventional compartments chemical properties such as shape and size, of the respiratory tract discussed inconnec- but also on the site of initial deposition. Fur- tion with the deposition modelare used here. thermore, the presence ofa nonparticulate DI is the particulate material inhaled; irritant or the coexistence of D2 a disease state is the material in the exhaled air;D3, D4, and in the lungs may interfere with theefficiency D5 are the particles depositedin the naso- of clearance mechanisms and thusprolong pharyngeal, tracheabronchial, and pulmonaty the residence time of particulate materialin compartments respectively, expressedas per- a given area of the respiratory tract. Kotin centages of DI and _determinable from the and Falk 38 have emphasized the possibleim- deposition model. In addition to the respira- portance of this, interaction in the patho- tory tract, three other compartmentsare genesis of lung cancer (Chapter 10). listed: The gastrointestinal tract,systemic 1.Clearance Model blood, and the.lymph. The differentabsorp- tion and translocationprocesses which are The Task Group on Lung Dynamics con- associated with the clearance of variouscom- sidered the respiratory clearance ofparticu- partments are as follows: 714Wi..` a. Rapid uptake of material deposited values are physiologically controlled and are in the nasopharynx directly into the more or less independent vf the nature of

bloodstream. , the particulate material. In other cases the b. Rapid clearance ofallparticulate physiochemical nature of the deposited mate- matter from the nasopharynx by cil- rial is the critical factor. iary transport of mucus. This route, A classification of inorganic compounds is and d, have clearance half-times of given in the Task Force Group Report, which minutes. contains the best available information or c. Rapid absorption ofparticlesde- both deposition and clearance of inhaled posited in the tracheobronchial com- particles. partment into the systemic circula- The Task Force Group stressed the need tion. for research in the area of solubilities of d. The rapid ciliary clearance of the various compounds in water, in very dilute tracheobronchial compartment. Par- alkali, and in the presence of proteins. Some ticles cleared by this route go quan- of the work done by Morrow et al." corre- titatively to the gastrointestinal tract. lates clearance of material from the lungs e. The direct translocation of material with other properties such as ultrafilterabil- from the pulmonary region to the ity and clearance from intramuscular injection sites.These data will be of value in understanding the effect of physiochemical f. The realtively rapid clearance phase properties on clearance. of the pulmonary region dependent on recruitable macrophages. This in It will be seen that the clearance mecha- turn is coupled to the ciliary mucus nisms can be divided broadly into those de- transport process for which a half- pending on ciliary action and those which time of 24 hours has been suggested. operate in the virtually nonciliated pulmonary region. The two sections which follow g. A second pulmonary clearance proc- describe experimental work concerned with ess, much slower than f, but still de- theie two general subdivisions. pendent upon endocytosis and ciliary mucus transport.This processis 2.Clearance from the Tracheobronchial rate-limited in the pulmonary region System by the nature of the particles per se. h. The slow removal of particles from A blanket of mucus in the tracheobron- the pulmonary compartment via the chial region is kept in continual upward lymphatic system. movement by the ciliary activity of the col- i. A secondary pathway in which par- umnar epithelium lining which extends down ticles cleared by pathway h are intro- as far as the terminal bronchioles. The fre- duced into the systemic blood. quency of the ciliary beat has been found 4o 41 to be 1,300 per minute in the rat, while the j. The collective absorption of cleared overlying mucous fluid was found to move material from the gastrointestinal at an average rate of 13.5 mm per minute. tract into the blood. No attempt is Similar transport rates of 15 mm per min- made to include this factor in the de- ute in excised trachea, and 18 mm per min- velopment of the model. ute in intact animals, have been reported by The use of the model requires a knowledge Antweiler.42 In this latter study, several par- of values for two parameters for each of the ticulate materials were used, including soot, pathways just described.These are the coal dust, lycopodium spores, cork dust, alu- amount of material. residing in,the compart- minum powder, and ,glass and lead spheres. ment which follows a particular exit path Transport rates seemed to be unaffected by (regional fraction), and the rate at which sized weight, or shape of the particles except that fraction of the material is cleared (bio- in the case of the glass spheres, which were logical half-time). In some cases the kinetic said to be sufficiently smooth to &flow the

121 'LOU. mucus to flow over them rather than to trans- acute response to irritant gases such as am- port them. monia, formaldehyde, or sulfur dioxidewas It has been demonstrated 43.44 that in the a cessation of ciliary beat. The time to ces- human lung the mucus flows over only 10 sation was dose-related. Chronic exposure percent to 20 percent of the theoretically of rats to one of the irritants (sulfur dioxide) available surface at the dividing passages slowed down or caused a complete cessation where the airways branch. The mucous of the transport of tracheal mucus, but the blanket divides and flows in two directions average beat frequency of the cilia was the around the margins of the opening. This same as in normal animals. The cessation phenomenon, taken together with the greater of clearance was a result of an increase in the probability of impact deposition at bifurca thickness of the mucous layer of from 5A tions, may explain why histological sections to 25 A. show accumulations of particles at bronchial The material carried upward by ciliary branch points.49 action is swallowed and thui enters the gas- In studies of respiratory system clearance, trointestinal tract.Brieger and LaBelle 49 use has been made of mono-disperse aerosols exposed animals to a water-insoluble dye and tagged with radioactive substances to per- demonstrated that 24 hours after the termi- mit the subsequent fate of the material to nation of exposure, over 50 percent of the be followed by external counting techniques. total dye found in the body was in the in- In general, the results indicate that clear- testinal tract. This phase could persist for ance occurs in two distinct phases of about several days, during which time a significant two and ten hours duration, probably repre- intestinal burden was present. The concen- senting the clearance of particles from the tration of dye finally fell to very low values proximal and distal 'Parts of the bronchial after a week or so, and most of the dye that tree. Albert et al." studied clearance from remained in the body was found in the lung, the human lung of 3-p and 5-µ iron oxide indicating that the rapid phase of ciliary particles tagged with 51Cr and 198Au. The clearance was finished.It has also been rapid phase of clearance was completed with- shown 50 that uranium dioxide, cleared from in one day, and in most cases within 12 the respiratory system to the gastrointestinal hours.The clearance curves obtained in tract by ciliary action, is responsible for the these studies did not differ substantially high urinary uranium levels seen during the from those obtained earlier by Albert and first days after exposure to uranium dioxide Arnett 47 who used a heterogeneous ironox- dust. The possibility of consequences of rela- ide aerosol, suggesting that. the actual dis- tively high concentrations of an atmospheric tribution function of particle sizes may be pollutant appearing in organs remote from of little importance in determining clearance the lungs must not be overlooked.In this rates.However. Holma 49 generated a "bi- connection, the high incidence of stomach disperse" aerosol of 6-p and .3-p polystyrene cancer in areas suffering from high levels particles, tagged respectively with 399Au and of atmospheric pollution takes on a particu- 48sc, and measured simultaneousclearance larly ominous appearance. of the two sizes in rabbits. The largerpar- ticles cleared more rapidly than the smaller 3.Clearance from the Alveolar Surface ones. The mean half-life for the initial phase Particles) deposited on the alveolar sur- was 0.48 hours for the 6-p particles and 1.07 face may be removed by any of the mecha- hours for the 3-p particles: The respective nisms (e) to (i) given in the clearance model half-lives for the long clearance phasewere of Section D-1, and they may also become 69.7 hours and 210 hours. sequestered by a tissue reaction within the The effect of irritant gases on clearance of lung (pneumoconiosis), or become bound to partieles is obviously of significance where protein material in the lungs. Of thesev- air pollution involvev.this combination of eral clearance mechanisms, the most rapid is factors. :t* thatinvolvingrecruitablemacrophages Dalhamn's 40° 41 studies showed that the (phagocytic cells contained on the alveolar 122 surface epithelium). Phagocytosis may also respiratory bronchioles and alveolar ducts serve to render the particles incapable of in- may help to explain the greater vulnerability juring or irritating the alveolar surface epi- of these regions to inhaled irritants. thelium and may to some extent prevent the penetration of the particles into the inter- E.SUMMARY stitium of the lung. The origin and behavior The respiratory system may be divided of these alveolar macrophages have been into three sectionsnasopharyngeal,tra- the subjects of active research in recent cheobronchial, and pulmonary systems. Dep- years.45. 51-53 osition and clearance mechanisms may differ LaBelle 54. 58 demonstrated that the clear- for the various parts of the respiratory tract. ance of particulate matter by phagocytosis A particle of any size which passes the naso- can be markedly influenced by the dust load pharyngeal region may be deposited in the presented to the lung. The initial observa- remainder of the respiratory tract and, al- tion was made that clearance curves obtained though the actual mechanism of deposition with microgram quantities of activated ura- is primarily dependent upon the particle size, nium dioxide were noticeably different from the shape of the particle can also affect the thoseobtainedearlierusingmilligram efficiency of its deposition. Consequently, if amounts. When carbon particles were added atmospheric dust loads are to be related to the activated uranium dioxide to bring quantitatively to health hazards, the dust the total weight of administered dust into samplers used for monitoring should have the range of the earlier studies, the clearance collection characteristics similar or the same curves were quite similar.In seeking the as the human lung. The fast phases of the reason for this finding.LaBelle demon- lung clearance mechanisms are different in strated that the number of free phagocytes ciliated and nonciliated regions. In ciPated washed out of the lungs was related to the regions, a flow of mucus transports the par- dust load and that the amount of dust elimi- ticles to the entrance of the gastrointestinal nated from the lungs during the early post- tract, while in the nonciliated pulmonary re- exposure period was proportional to the num- gion phagocytosis by macrophages can trans- ber of free phagocytic cells present. Within fer particles to the ciliated region. The rate the limits of experimental error, the kinetics of clearance is an important factor in de- of elimination of particles and the kinetics termining toxicresponses,especially for of the disappearance of the phagocytic cells slow-acting toxicants such as carcinogens. following exposure were identical for both In addition, since the clearance of particles inhalation and intratracheal exposures. from the 'respiratory system primarily leads The relationship between concentrations in to their entrance into the gastrointestinal the different respiratory regions during al- system, organs remote from the deposition veolar clearance has been the subject of a site may be affected. The models developed short-term study by Gross, Pfitzer, and by the Task Group on Lung Dynamics are Hatch.56 The clearance of four kinds of dust used in this chapter as a basis for discussion burdens (antimony trioxide, ferric oxide, of experimental data on the deposition, re- quartz, and coesite) was followed in rats tention, and clearance of particles.These whose lungs had been loaded using the in- models provide a useful representation of halation and intratracheal injection tech- the deposition and clearance mechanisms and niqnes. Initially, although the greater con- have been shown to yield predictions which centration of dust was to be found in the have often been substantiated by experimen- proximal alveoli, dust deposition was also tal findings. prominent in alveoli distal to alveolar ducts. F.REFERENCES However, within .3 or 4 days, the dust in the distally situated alveoli had largely disap-, 1. Hatch, T. F. and Gross, P. "Pulmonary Depo- sition and Retention of Inhaled Aerosols." Aca- peared and had apparently become concen- demic Press, New York, 1964. trated in the proximal alveoli. This stagna- 2.'iMorrow, P. E. "Some Physical and Physiologi- tion of dust in the evaginating alveoli of the fag Factors Controlling the Fate of Inhaled Sub- stances.I. Deposition." Health Physics, Vol. 2, J. Pharmacol. Exper. Therap., Vol. 21, pp. 47-57, pp. 366-378, 1960. 1923. 3. Davies, C. N "Inhalation Risk and Particle Size 20.Sayers, R. R., Fieldner, A. C., Yant, W. P., in Dust and Mist." Brit. J.. Ind. Med., Vol. 6, Thomas, B. G. H., and McConnel, W. J. "Ex- p. 245, 1949. . haust Gases from Engines Using Ethyl Gaso- 4. "Deposition and Retention Models for Internal Dosimetry of the Human Respiratory Tract." line." U.S. Dept. of Interior, Bureau of Mines, Task Group on Lung Dynamics. Health Physics, Report of Investigations 2661, 1924, 24pp. Vol. 12, pp. 173-207, 1966. 21.Drinker, P., Thompson, R. M., and Finn, J.L. 5. Miller, W. S. "The Lung." 2nd edition. Thomas, Quantitative Measurements of the Inhalation, Springfield, Illinois, 1947. Retention, and Exhalation of Dust and Fumes 6. Krahl, V. E."Microscopic Anatomy of the by Man. I. Concentration of 50 to 450mg per Lungs." Am. Rev. Respirat. Diseases, Vol. 80, cubic meter." J. Ind. Hyg. Toxicol., Vol. 10,pp. pp. 24-44, 1959. 13-25, 1928. 7. Davies, C. N. "A Formalized Anatomy of the 22.Van Wijk, A. M. and Patterson, H. S."The Human Respiratory Tract." In: Inhaled Par- Percentage of Particles of Different Size, Re- ticles and Vapours, Vol. 1, C. N. Davies (ed.), moved from Dust Laden Air by Breathing." J. Pergamon Press, London, 1961, pp. 81-91. Ind. Hyg. Toxicol., Vol. 22, pp. 31-35, 1940. 8. Mitchell, R. I. and Tomashefski, J. F. "Aero- 23.Brown, C. E. "Quantitative Measurements, of sols and the Respiratory Tract." Battelle Techn. the Inhalation, Retention, and Exhalation of Rev., Vol. 13, pp. 3-8, 1964. Dust and Fumes by Man. II. Concentration be- 9. Silverman, L., Lee, G., Plotkin, T., Sawyers, L. low 50 mg per cubic meter." J. Ind. Hyg. Toxi- A., and Yancey, A. R. "Air Flow Measurements col., Vol. 13, pp. 285-291, 1931. on Human Subjects with and without Respira- 24.Brown, C. E."Quantitative Measurements of tory Resistance at Several Work Rates.". Arch. the Inhalation, Retention, and Exhalation of Ind. Hyg., Vol. 3, pp. 461-478, 1951. Dust and Fumes by Man. III. Factors Involved 10. Amdur, M. 0., Silverman, L., and Drinker, P. in the Retention of InhaledDusts and Fumes "Inhalation of Sulfuric Acid Mist by Human by Man." J. Ind. Hyg. Toxicol., Vol. 13,pp. Subjects." Arch. Ind. Hyg., Vol. 6, pp. 305-313, 293-313, 1931. 1962. 25. 11. Altshuler, B., Palmes, E. D., Yarmus, L., and Altshuler, B., Yarmus, L., Palmes, E. D., and Nelson, N. "Aerosol Deposition in the Human Nelson, N. "Intrapulmonary Mixing of Gases Respiratory Tract. I. Experimental Procedures Studied with Aerosols." J. Appl. Physiol., Vol. 14, pp. 321-327, 1959. and Total Deposition." Arch Ind. Health, Vol. 151 pp. 293-303, 1957. 12. Findeisen, W. Ober das Absetzen kieiner in der 26. Luft suspendierten Teilchen in der menschlichen Dautrebande, L. and Walkenhorst, W. "Ober die Lunge bei der Atmung." Arch. Ges. Physiol., Vol. Retention von Kochsaltteilchen in den Atema- 236, pp. 367-379, 1935. gen." In: Inhaled Particles and Vapours, Vol. 1, C. N. Davies (ed.), Pergamon Press, London, 13. Landahl, H. D. "On the Removal of Airborne 1961, pp. 110-121. Droplets by the Human Respiratory Tract. I. 27.Dautrebande, L., Bechmann, H., and Walken- The Lung." Bull. Math. Biophys., Vol. 12,pp. 43-56, 1959. horst, W. "Lung Deposition of Fine Dust Par- ticles." Arch. .Ind. Health, Vol. 16,pp. 179-187, 14. Weibel, E. W. "Morphontetry of the Human 1957. Lung." Academic Press, New York, 1963. 28.Dennis, W. L. "Discussion of Davies." In: In- 15. Landahl,_ H. D. "On the Removal of Airborne haled Particles and Vapours, Vol. 1, C. N. Davies Droplets by 'the Human Respiratory Tract. II. (ed.), Pergamon Press, London, 1961,pp. 88-91. The Nasal Passages." Bull. Math. Biophys., Vol. 29. 12, pp. 161-169, 1950. Morrow, P. E. and Gibb, F. R. "The Deposi- tion of a Submicronic Aerosol in the Respiratory 16. Lehmann, K., Saito, Y., and Girorer, W. "Ober Tract of Dogs." Am. Ind. Hyg. Assoc. J., Vol. die quantitative Absorption von Staubaus der 19, pp. 196-200, 1958. Luft durch den Menschen." Arch. Hyg. Bak- 30. Landahl, H. D., Tracewell, T. N., and Lassen, teriol., Vol. 75, pp. 152-459, 1912. W. H. "Retention of Airborne Particulates 17. Saito, Y. "Experimentelle Untersuchen fiber in die the Human Lung." III.. Arch Ind. Hyg.,Vol. quantitative Absorption von Staub durch Tiere 6, pp. 508-511, 1952. bei Genau Beakafintem. Staubgehalt der Luft." 31 Arch. Hyg. Balcteriol., Vol. 75, . Lehmann, C. "The Dust Filtering Efficiency of pp. 134-151, 1912. the Human Nose and itsSignificance in the 18. Owens, J. S."Dust in. Expired Air." Trans. Causation of Silicosis." J. Ind. Hyg. Toxicol., Med. Soc. (London), Vol. 45, pp. 79-90, 1923. Vol. 17, pp. 37-40, 1935. 19. Baumberger, J. P. "The Amount of SmokePro- 32.Tourangeau, F. J. and Drinker, P. "Dust Fil- duced from Tobacco and the Absorption in Smok- tering Efficiency of the Human Nose." J.Ind. ing as Determined by ElectricPrecipitation." Hyg. Toxicol., Vol. 29, pp. 53-57, 1937. 124 33. Landahl, H. D. and Black, S. "Penetration of 45. Casarette,L.J."Autoradiographic Observa- Airborne Particulates through the Human Nose." tions after Inhalation of Polonium** in Rats." J. Ind. Hyg. Toxicol., Vol. 29, pp. 269-277, 1947. Radiation Res. (Suppl.), Vol. 5, pp. 187-204, 34. Landahl, H. D. and Tracewell, T. N. "Penetra- 1964. tion of Airborne Particulates through the Hu- 46. Albert, R.E., Lippman, M., Spiegelman, J., man Nose." II.J. Ind. Hyg. Toxicol., Vol. 31, Strethlow,C.,Briscoe, W., Wolfson, P., and pp. 55-59, 1949. Nelson, N. "The Clearance of Radioactive Par- 35. Wilson, I. B. and LeMer, V. K. "The Retention ticles from the Human Lung." In: Inhaled Parti- of Aerosol Particles in the Human Respiratory cles and Vapours, Vol. II, C. N. Davies (ed.), Tract as a Function of Particles Radius." J. Pergamon Press, London, 1967, pp. 361-378. Ind. Hyg. Toxicol., Vol. 30, pp. 265-280, 1948. 47. Albert,- R. E. and Arnett, L. C. "Clearance of 36. Brown, J. H., Cook, K. M., Ney, F. G., and Hatch, Radioactive Dust from the Lung." Arch. Ind. T. F. "Influence of Particle Size upon the Re- Health, Vol. 12, pp. 99-106, 1955. tention of Particulate Matter in the Human 48. Holma, B. "Short Term Lung Clearance in Rab- Lung." Am. J. Public Health, Vol. 40, pp. 450- bits Exposed to a Radioactive Bi-disperse (6 458, 1950. and 3) Polystyrene Aerosol." In: Inhaled Parti- 37. Palm, P. E., McNerney, J., and Hatch, T. F. cles and Vapours, Vol. II, C. N. Davies (ed.), "Respiratory Dust Retention in Small Animals. A Comparison with Man." Arch. Ind. Health, Pergamon Press, London, 1967, pp. 189-203. Vol. 13, pp. 355-365, 1965. 49. Brieger, H. and LaBelle, C. W. "The Fate of 38. Kotin, F. and Falk, H. "Atmospheric Factors Inhaled Particulates in the Early Pcstexposure in Pathogenesis of Lung Cancer." Advan. Can- Period." Arch. Ind. Health, Vol. 19, pp. 510-515, cer Res., Vol. 7, pp. 475-514, 1963. 1959. 39. Morrow, P. E., Gibb, F. R., Davies, C. N., and 50. Downs, W. L. "Excretion of Uranium by. Rats Fisher, M. "Dust Removal from the Lung Para:- FollowingInhalationof UraniumDioxide." chyme :An Investigation of Clearance Simu- Health Physics, Vol. 13, pp. 445-453, 1967. lants."Toxicol. Appl. Pharmacol. Vol. 12, pp. 51. Casarett, L. J. "Some Physical and Physiologi- 372-396, 1968. cal Factors Controlling the Fate of Inhaled Sub- 40. Dalhamn, T. "Mucous Flow and Ciliary Activity stances.II.Retention." Health, Physics, Vol. in the Trachea of Healthy Rats and Rats Ex- 2, pp. 379-386, 1960. posedtoRespiratory Irritant Gases."Acta 52. Casarett, L. J. and Milley, P. S.41Alveolar Re- Physiol. Scand., Suppl. 123, 1956. activityFollowingInhalationofParticles." 41. Dalhamn, T. "A Method for Studying the Effect Health Physics, Vol. 10, pp. 1003-1011, 1964. of Gases and Dusts on Ciliary Activity in Living 53. Policard,A.,Collet,A., and Pregermain, S. Animals." In: Inhaled Particles and Vapours, "Structures alveolaires norfaales du pneumon Vol. 1, C. N. Davies (ed.), Pergamon Press, Lon- examines au microscope electronique." Semaine. don, 1961, pp. 315-317. Hop. (Paris), Vol. 33, p. 355,1957. 42. Antwiler, H. "Ober die Funktion des Flimmer- epithels der Luftwege inbesondere unter Staub- 54. LaBelle, C. W. and Briefer, H."Synergistic belastung." Beitr.Silkose-Forsch., Sonderband, Effects of Aerosols. II. Effects on Rate of Clear- Vol. 3, p. 509, 1958. ance from the Lung." Arch. Ind. Health, Vol. 20, 43. Hilding, A. C. "On Cigarette Smoking, Bron- pp. 100-105, 1959. chial Carcinoma, and Ciliary Action.III. Ac- 55. LaBelle, C. W. "Patterns and Mechanisms in cumulation of Cigarette Tar upon Artificially the Elimination of Dust from the Lung." In: Produced Deciliated Islands in the Respiratory Inhaled Particles and Vapours, Vol. 1, C. N. Epithelium." Ann. Otol. Phinol. Laryngol., Vol. Davies (ed.), Pergamon Press, London, 1961, pp. 65, pp. 116-130, 1956. 356-368. 44. Hilding, A. C. "Ciliary Streaming in the Bron- 56. Gross, P., Pfitzer, E. A., and Hatch, T. F. "Al- chial Tree and the Time Elements in Carcino- veolar Clearance: Its. Relation to Lesions of the genesis." New Engl. J. Med., Vol. 256, pp. 634- Respiratory Bronchiole." Am. Rev. Respirat. 640, 1957. Diseases, Vol. 94, pp. 10-19, 1966. 9

134 125 Chapter 10

TOXICOLOGICAL STUDIES OF ATMOSPHERIC PARTICULATE MATTER

135 Table of Contents Page. A. INTRODUCTION 129 B. MECHANISMS OF TOXICOLOGICAL ACTIONOF PARTICULATE MATTER 129 1. Intrinsic Toxicity 129 2. Absorbed Substances 130 3. Reduction of the Toxicity of Irritant Gases 130 C. TOXICOLOGICAL STUDIES OF SPECIFICPARTICULATE MATERIALS 131 1. Pathological Studies of Smoke and Carbon Particles i31 2. Physiological Studies of Response to ParticulateMaterial 132 3. Experimental Studies of Mixtures of Irritant Gasesand Particulate Material 134 D. CARCINOGENESIS 137 1. Carcinogens 137 2. Polynuclear Aromatic Hydrocarbonsas Carcinogens in Polluted Atmospheres 138 3. Pathology of Carcinogenesis 141 E. SUMMARY 141 F. REFERENCES 142

List of Tables Table 10-1Effect of Exposure of Rabbits to 2ppm Ozonized Gasoline on Re- tention of Inhaled Soot 134 10-2 Benzo (a) pyrene Concentrations inSeveral Urban and Nonurban Areas 138 10-3 Benzo (a) pyrene as a Fraction of the TotalAromatic Hydrocarbon Content of Several Urban Atmospheres 138 10-4Effect of Various Conditions of Exposureon the Destruction of Some Polynuclear Aromatic Hydrocarbons 139 10-5Percentage Recovery of Polynuclear Aromatic Hydrocarbonsfrom 0.51A Soot Particles and from Plasma after Incubation withPlasma for Varying Periods 140. 10-6Distribution of Lung Cancer by Site of Origin 141 Chapter 10 TOXICOLOGICAL STUDIES OF ATMOSPHERIC PARTICULATE MATTER

A.INTRODUCTION "inert" particle in the respiratory tract may interfere with tha clearance of other air- Experimentaltoxicology,using specific borne toxic materials; and third, the particle atmospheric pollutants, would be the best..may act as a carrier of toxic material. There means for deriving air quality criteria, pro- is also evidence that the presence of particles vided that man could be used as the experi- may occasionally reduce the toxicity of a mental animal. However, the ethical impos- second pollutant; this phenomenon isde- sibility of performing experiments using scribed briefly. From an air pollution stand- human exposures to varying concentrations point, one of the most ubiquitous'particulate of a wide range of compounds precludes so pollutants is smoke; some pathological stud- direct an approach. Although a limited ies involving this material are presented. amount of intentional human experimenta- Studies of physiological response to irritant tion may be possible, most of the data for particles and to mixtures of particulate mat- human toxocology are derived from acci- ter with irritant gases are described. dental or occupational exposures. The use of A final section of this chapter then deals laboratory animals in toxicological experi- with carcinogenesis and atmospheric pol- ments is more straightforward, but the ob- lutants. vious anatomical and metabolic differences between the animals and man require the ex- B.MECHANISMS OF TOXICOLOGICAL ercise of considerable caution in applying the ACTION OF PARTICULATE MATFER results of animal exposures to human health criteria. Furthermore, many of the animal 1.Intrinsic Toxicity experiments performed have left something Few common atmospheric particulate pol- to be desired in terms of air pollution toxicol- lutants appear to be intrinsically toxic; of ogy, since the "end-point" of the experiments these, the most important toxic aerosol is has frequently been the death of -the saimals sulfur trioxide (SO8)(either as the free at exposures to concentrations far in excess oxide, or hydrated as sulfuric acidH2SO4), of those likely to be found, or tolerated, in the which has a high degree of toxicity, at least atmosphere. There is a great need for chronic for the guinea pig. Although silica (from fly inhalation studies to define long-term effects ash) is frequently present as a pollutant, at- occurring over a lifespan. mospheric concentrations are normally too The difficulties and limitations of toxico- low to lead to silicosis. In recent years, how- logical studies discussed in the last para- ever, concern has been expressed over a num- graph should not obscure the fact that an in- ber of less common toxic particulate pollut- creasing amount of data useful for air quality ants, including lead, beryllium, and asbestos. criteria is being amassed; it is, however, al- Increasing amounts of lead (as oxides and ways essential to bear in mind the limitations salts) are being discharged into the atmos- of the data. Toxicological studies have shown. phere as a result of the burning of gasoline that atmospheric particles may elicit a path- containing lead additives; on the other hand, ological or physiological response in at least other sources contributing to atmospheric three ways. First, the particle may be in- lead seem to be decreasing and, according to trinsically toxic; second, the presence of an Stoldnger and Coffin,1 toxic effects due to ,. ..; 129 lead do not seem to present a serious risk to adsorbate may be carried by each particle. If the population at large. Beryllium (as the the adsorbate in its free state is slowlyre- oxide BeO) can lead to chronic pulmonary moved from the air in the respiratory system, disease with a high fatality rate. Accidental then the deposition of particles carrying high exposures have shown that .there may be a concentrations may constitute a greater toxic considerable latency period before disease hazard, especially at the localized deposition develops, and some alarm has been generated points. Whether or not the effect is signifi- over the use of beryllium as a rocket fuel, cant depends on the efficiency of the desorp- although the rocket effluent is predominantly tion and elution process relative to that of the a "high-fired," relatively inert form of beryl- clearance process. The chemical nature of lium oxide. The situation with regard toas- both adsorber and adsorbate, and the size of bestos is also potentially serious. Brief in- the adsorbing particle, all play a part in de- dustrial or accidental exposures to asbestos termining these various efficiencies, and each can lead, after a latency period of 40 years system will show its own individual charac- or more, to the development of diffuse meso- teristics. Carcinogens, which may produce theliomas of the pleura or peritonium, and it their effect only after long or repeatedex- is possible that sufficient levels of asbestos posure, present a particularly involved situa- might be generally present in the atmosphere tion, because it is not clear whether slowre- to constitute a definite health hazard. This lease of small concentrations of the carcino- possibility is made more likely by the greatly gen is more dangerous than the rapid release increased use of asbestos since theoccur- of larger quantities. Experimental evidence rence of the exposures which are only now on the elution of ..a specific series of carcino- leading to the development of mesotheliomas. gens is described in Section D-2. A series of autopsies has shown thatan appreciable fraction (20 percent to 50 percent) 3.Reduction of the Toxicity of Irritant of the population at large has "asbestos Gases bodies" in its lungs. More detailed discussions The finding that a preexposure to particu- of both asbestos = and beryllium = toxicity late material will tend to protect animals may be found in recent reviews. against the action of an irritantgas is not an Several other potential carcinogensare uncommon one. known to be present as relatively minor at- Pattie and Burgess found that, with mice mospheric pollutants; these may be particu- and guinea pigs, the previous inhalation of late in nature, and they are discussed in smoke reduced the toxicity of sulfur dioxide Section D. (measured in terms of the dosage required 2.Adsorbed Substances to produce death). They postulated that the reduced toxicity of SO2 produced bypreexr Toxic substances may be adsorbedon the posure to smoke was due either to the action surface of particulate matter, whichmay of the smoke in reducing the volume breathed then carry the toxic principle into the respi- (and thus the SO2 dose received), or to a ratory system. The presence of carbonor stimulation of secretions whichmay protect soot as a common particulate pollutant is the mucosa from the irritant action ofthe noteworthy, as carbon is well knownas an gas. This explanation is given weight by their efficient adsorber of a widerange of organic findings that increased toxicity resulted from and inorganic compounds. Some specific stud- the administration of mixtures of smoke and ies involving mixtures of particulate matter sulfur dioxide. A similar study by Salem and and irritant gases are presented in Section Cullumbine 5 indicated that the effect of kero- C-3; the present section is concerned mainly sene smoke on the toxicity of irritant sub- with the general principles of adsorption and stances depended to some extenton the spe- desorption. cies of animal, althougl, the toxicity ofacro- The role played by the affinity for the ad- lein and acetaldehyde seemed to be decreased sorbate by the particle is complex..A high af- in most cases. finity will mean that relatively large loads of . agner et ai.° observed that the preex- ..:1 130 posure of mice to oil mists would protect that were examined several months to a year against the later action of inhaled ozone and after the exposure. The authors state that nitrogen dioxide..The greatest protection was these lung changes were analogous to those obtained when the oil mist was given 18 seen in a milder grade of bituminous pneu- hours prior to the exposure to the irritant moconiosis of soft-coal miners, and they also gas; when the oil mist and irritant gas were concluded that the pneumonitis and fibrosis given together, there was an enhancement of were attributable to the carbon rather than toxicity. The relative degree of this enhance- to the small amount of silica present. . ment was consistent with the known depth of Schnurer P. has also attempted to compare penetration of nitrogen dioxide and ozone in the response to the burning of equal weights the respiratory tract and the relative solubil- of anthracite coal, coke, and bituminous coal. ity of the two gases in mineral oil. The hy- Unfortunately, widely differing particle con- pothesis for the protective action of the pre- centrations were obtained from burning equal treatment with oil is the formation of an oil weights of fuel, so that it is impossible to film on the aveolar surface. place any simple interpretation on the re- Again, Amdur and Devir,' using guinea sults of the experiments. pigs, have observed that the presence of an Pattie et al.'° studied the acute toxic effects aerosol of 2.5p, triphenyl-phosphate particles of smoke, generated by burning tetrahydro- at a concentration of 50 mg/m3 to 100 mg/m3 naphthalene in the concentration range of lessens the increase in pulmonary flow re- 700 mg/m3 to 1100 mg/m3. They found that sistance due to inhalation of sulfur dioxide. the median dosage to death for guinea pigs They then studied the effect of treatment and mice lay between 147,000 mgmin/m3 to with the particulate material before expo- 351,000 mgminims. In mice, the cause of sures to sulfur dioxide alone. This sequence death was blockage of the air passages and afforded excellent protection against the re- delayed death resulting from the exposure sponse to the sulfur dioxide, and the degree was unusual. The guinea pigs showed hemor- of protection was related to the total amount rhagic lesions, and delayed deaths were more of aerosol inhaled. common. The action of smoke on rats re- sembled that on mice. No data are provided C. TOXICOLOGICAL STUDIES OF to show that unburnt tetrahydronaphthalene SPECIFIC PARTICULATE MATERIALS did not enter the smoke stream in these experiments, since toxic effects are well known 1.Pathological Studies of Smoke and for this substance. Carbon Particles In the course of a study of mixtures of Smoke from burning bituminous coal was sulfur dioxide and smoke, to be discussed in used for a study on rabbits and rats by Section C-3, Pattie and Burgess4 reported Schnurer and Haythorn.8 Four rabbits and some data on the effect of smoke alone on eight rats were exposed for periods of 80 mice. The smoke was generated by a burning days to smoke with a concentration of 125 kerosene lamp, and its concentration was million particles/fts (4410 particles/cm3), of about 50 mg/ms. The experiment continued which 8 percent was free Si02. Control ani- for 36 hours followed by a gap of 11 hours. mals received clean filtered air. One control The experiment was subsequently continued rabbit and two exposed rabbits died of bron- for 30 hours. There were no fatalities and chial pneumonia before the end of the expo- none occurred after the experiment. Histo- sure. One rabbit and six rats were autopsied logical examination of the lungs slimed that immediately after exposure, and the rest at at the end of exposure the soot particles were intervals up to 429 days. Lesions typical of partly spread over the lining of the bron- nonoccupational anthracosis were noted in chioles and alveoli and partly aggregated into the lungs of the animals killed immediately patches. There were no signs of edema, con- after exposure, while fibrous reactions de- solidation, hemorrhage, or, emphysema. and veloped around the carbon deponita (with the capillary congestion was slight. The lungs formation of collagen strands) in the animals were normal except for the presence of car- , 181 Een

-.3

bon particles, and animals killed 3 months when the organisms were suspended in mucin afterexposure showed phagocytosis and but not when they were injected ina broth gradual clearance of smoke from the lungs. medium. Salem and Cullumbine 3 also make brief Based upon the reported studies, smokeor mention of the exposure of mice and guinea carbon black on its own apparently produces pigs to smoke from a kerosene lamp. The little major damage to the respiratory system animals survived exposure to 664 mg/m3of of animals even at exposure levelssome smoke for 6 hours, and autopsy revealedno orders of magnitude greater than thoseen- obvious damage to the lungs. countered in polluted atmospheres. The physiological effectson mice of exposure to carbon black by ingestion, skincon- 2.Physiological Studies of Response tact, subcutaneous injection, and inhalation to Particulate Material were examined by Nau et al."-" Channel Certain particulate materials are pulmon- black ( particle diameter 0.0250 andfurnace ary irritants which have been shown to pro- black (particle diameter 0.0850were used in duce alterations in the mechanical behavior concentrations of 2.4 mg/m3 and 1.6 mg/m3 of the lungs, the alteration being predomi- respectively for the inhalation experiments. nantly an increase in flow resistance. This Mice, hamsters, guinea pigs, rabbits,and was demonstrated by Amdur 19 for sulfuric monkeys were exposed for prolonged periods acid, and by Amdur and Corn 20 foram- to the dust, but no effect other than theac- monium sulfate, zinc sulfate, and zincam- cumulation of carbon particles in the lungs monium sulfate, using the guinea pigas an was demonstrated. assay. animal. (The decreased flow rates ob- The problem of whether exposure of rats served by Amdur, Silverman, and Drinker23 to coal dust or smoke would alter theirsus- in human subjects exposed to sulfuric acid ceptibility to infection by Type Ipneumo- mist probably reflect an increase in flowre- cocci was examined by Vintinner andBaet- sistance, although, since the resistancewas jer 15 as part of a series of studieson the ef- not measured in those experiments, sucha fect of fibrous, inert, and adsorptivedusts on statement cannot be conclusive.) A series of susceptibility to infection in experimental papers making use of the increase in pulmon- animals.36-18 The concentration of coaldust ary flow resistance as an assay tool has been varied between 400 and 850 millionparticles/ published by Amdur,22-2/ and "response"to ft3 with an average of 700 millionparticles/ an irritant in discussion of her work general- ft3. The smoke level in the chamberswould ly refers to this increase. have been consideredas "dense" on visual Nadel et al.2" report a correlation between inspection, or equivalent to abouta Number the alterations in pulmonary mechanics 8 reading on the Ringelmann Chart. and Analyses actual anatomical change in cats exposedto of the particulate matter inmg/m3 in the aerosols of histamine and zinc ammonium smoke chamber averagedas follows: Total sulfate. The authors discuss the physiological solids - -570, carbon-470, ash-93, silica-mechanisms which may operate tobring 46, iron-15, and sulfur-9, thatis, about about such alterations in pulmonaryme- 100 times the values listedas "average com- chanics. position of susupended dust duringthe win- In connection with a study of the effect of ter months for all cities." Theexposures various aerosols on the increase in pulmonary ranged from 5 days to 165 days forthe bitu- flow resistance in guinea pigs producedby minous coal dust and from 2 days to154 days sulfur dioxide, Amdur and Underhill 22first for the smoke. On the basis of theirextensive examined the response to the aerosolsalone. data, the authors concluded thatthe inhala- These aerosols included spectrographic tion of smoke did not alter the car- susceptibility bon at 2 mg/m3 and 8 mg/m3, activatedcar- to infection when the organisms,either in bon at 8.7 mg/m3, manganese dioxide at broth or in mucin, were administered 9.7 by inmg/m3, open hearth dust at 7.0 mg/m3,iron trabronchial injection. The bituminouscoal oxide (Fe208) at 11.7 mg/m3 and 21.0mg/m3, dust seemed to exert a slight protectiveeffect manganous chloride and ferrous sulfate at 132 4i1- 1 mg/m3. and sodium orthovanadate at 0.7 tides have been measured. Clouds containing mg/m3; the particle sizes were less than 0.5p. 8 mg/m3, 9 mg/m3, 19 mg/m3, 33 mg/m3, and Standard one-hour exposures were used in 50 mg/m3 dust in the size range of 1p to 7p this routine bioassay method, with the ex- were used. Normal subjects inhaled the dust ception of the iron oxide exposure, which for 4 hours, and airway resistance was meas- were extended to two hours. In no instance ured with a body plethysm'ograph. No chang- did any of the aerosols produce an alteration es were obtained after the inhalation of coal in flow resistance. The failure of the aerosols dust from clouds containing 8 mg/m3 or 9 to produce an increase in resistance in these mg/m3; but with concentrations of 19 mg/m3, experiments suggests that if they cause bron- 33 mg/m3. and 50 mg/m3, significant in- chial constriction, it must be only in extreme- creases in airway resistance occurred and ly high concentrations. From the point of the response was correlated with the quan- view of air pollution toxicology, none of them tity ofdust. One hour after exposure ceased, would be classed on this basis as pulmonary the airway resistance was about two-thirds irritants. An uncharacterized "fly ash" from back to normal. With the two highest concen- an oil-fired burner was also tested and proved trations,therespiratoryrateincreased inert; throughout the 4 hours, and subjects com- At a concentration of 1 mg/m3, ferric sul- plained of difficulty in breathing after one to fate aerosol produced a 77 percent increase in two hours. It would appear that if 8 mg/m3 flow resistance in a group of 15 animals or 9 mg/m3 produced no lung function change' which was statistically significant at the level in a 4-hour period, the material (cold dust) of P<0.001. Ferric sulfate, in distinction to and perhaps other "inert" particulate matter ferrous sulfate, must be clasged as an irri- would be unlikely to do so at any concentra- tant. tions likely to occur in air pollution. In Chap- On the other hand, Dautrebande and Du- ter 1, Table 1-2 shows a. maximum geometric Bois 29' 29 have reported constriction and inmean concentration of urban particulates in creased airway resistance in isolated guinea 1961 to 1965 of 180 µg /m3. pig lungs and in human subjects with a wide Particle size may .play an important part variety of supposedly "inert" particulate mat- in determining the potency of an irritant. ter. The relationship of their results to Am- For example, at a mass concentration of 1.4 dur's work is not clear. since Dautrebande's mg/m3 to 1.9 mg/m3, sulfuric acid mist of particle concentrations appear to be ab- 0.8p produces a 51 percent increase in pul- normally high. Total lung capacity and vital monary flow resistance in guinea pigs as capacity were not altered by the inhalation compared to control values," and zinc am- of particulate material in healthy subjects, monium sulfaik particles of 0.84p produce a but the vital capacity in patients with 'pul- 21 percent increase." If the zinc ammonium monary disease was reduced by the inhala- sulfate size is 0.8p. the corresponding in- tion of particulate materials. it is interesting crease in pulmonary flow resistance is 180 in this connection that guinea pigs with an percent." The studies on zinc ammonium initially high pulmonary flow resistance sulfate were carried out by Amdur and showed a greater response to low concen- Corn 20 with nonhomogeneous aerosols with trations of irritant aerosols or of inert aero- mean sizes by weight of 0.24p, 0.51p, 0.74p, sol-irritant gas combinations than .animals and 1.4p., at several concentrations. As the with average control flow resistance values." particle size decreased over the range 1.4, The possibility that the conflict between to 0.29p, the response to an equal mass con- Amdur's and Dautrebande's work may be centration rose. When dose-response curves resolved in terms of the doses involved is of percent increase in flow resistance against given credence by studies which suggest that concentration in mg/m3 were plotted for the human response to coal dust may be dose- different particle sizes, the slopes increased related." Coal dust clouds similar to those in as the particle size decreased. A similar study mines have been produced in the laboratory, was undertaken by Amdur and Creasia 33 and the number and weight of respirable par- using m-terphenyl as the aerosol (size range 141 188 I.

0.3, to 2.0p.) ; this aerosol does not absorb the impingement of irritantson respiratory water during passage through the respira-. epithelium at branch points taken together tory tract. An essentially, identical pattern to with less efficient clearance is consistent with that seenfor zinc ammonium sulfate this result. Thus, abnormal retention andac- emerged, with the irritant potency increasing cumulation of soot (and possibly carcinogenic with decreasing particle size, and the slopes particles) may occur, especially in segmental of the dose-response curves steeper than bronchi. The accompanying peribronchial those for the smaller particles. All of the and peribronchiolar inflammatoryresponse particles used in these studies fall within furthein(rferes with physiologic mechan- the "respirable size range." The possibleim- isms o deense. plications for air pollution are: Experimental confirmation of enhancedre- . 1. Particles below 11i mAy have greater tention in the presence of irritant material

irritant potency than larger species,. is to be found in the work of Tremeret al.," and who exposed rabbits first to syntheticsmog 2..A small increase in concentration and then to soot. The resultsare shown in Table 10-1. could produce a greater-than-linear . increase in irritant response when The main conclusions of this sectionare: the particles are smaller than 44. 1.. The predominant physiological effect of irritants is to increase pulmonary The effect of particulate matteron clear- flow resistance; ance mechanisms has already beenmen- 2. Exceptionally heavy loads of tioned. The deposition of particles rela- affects tively inert particles maycause some mucous secretion and ciliary action most increase in flow resistance; and markedly atbranchings; e.g.,miniature 3. The intensity of physiologicresponse ridges throughout the tracheobronchialtree may increase with a .decrease in par- as contrasted with interveningareas, and it ticle size for any given irritant. is in the ridge areas thatalterations in the . . morphology are initially most intenseand 3.Experimental Studies of Mixtures of prolonged and ultimately irreversible.The Irritant Gases and Particulate Material adverse effect is manifested bya slowing of The possible influence of inert particulate the flow of the mucous stream, alteration in matter on the toxicity of irritantgases has the physical and chemicalproperties of been the subject of considerable mucus, and changes in ciliary action. speculation 35-37 and a limited amount ofexperimen- Examination of sections of respiratory tal work. Such interaction of gaseousand epithelium removed from thelungs reveal particulate pollutants might be important hyperplastic and metaplastic changes earli- to understanding the complicatedtoxicologi- est at these sites. The exaggeratedeffect of cal picture of the air pollution disasters. Table 10-I.EFFECT OF EXPOSURE OF RABBITSTO 2 PPM OZONIZED GASOLINEON RETENTION OF INIIALED SOOT.

Smog Room air Soot Room air Soot in Specimen exposure, (recovery), exposure, hours (recovery), lung, hours hours hours mg No recovery period after smogexposure: Control 0 0 1 0 Animal No. 1 1 3.7 0 1 0 7.9 Animal No. 2 0 With varying recovery periods: 1 24 6.4 Control 0 0 1 0 1.1 Animal No. 1 1 4 Animal No. 2 1 0 7.4 1 8 1 Animal No. 3 1 6.2 24 1 0 2.0

1 lM $41 The first experimental evidence that an particles. Ammonia is a highly soluble gas, inert aerosol could.alter the response to an'a so that synergism would have been predicted irritant gas was presented in 1939,3° when by LaBelle et al.41 Rats were exposed for it visa reported that concentrations of mus- 60 days to 100 ppm ammonia alone, 7 mg/ma tard gas which were relatively harmless to carbon alone, and to 119 ppm ammonia plus rats would produce pulmonary edema. and 3.5 mg/ma carbon. The carbon particles death when administered in combination were 95 percent smaller than 3 µ and 65 with an inert aerosol (sodium chloride). It percent smaller than 1 A. In the group ex- was postulated that the adsorption of gas posed to both ammonia and carbon, there was on the particles had increased the amount a high frequency of mucosal damage, and the of irritant vapor reaching the critical tar- ciliary activity seemed to be significantly get areas of the lung. Dautrebande and his impaired. The trachea of rats exposed to co-workers 33' 4° studied the sensory response ammonia alone showed less severe damage, of human subjects to pollutants thought to and the trachea was histologically normal in be constituents of the Los Angeles. smog and about 80 percent of the rats exposed to car- found that the presence of particles of so- bon alone. dium chloride, oil mist, or smoke, increase Boren 43 exposed mice to carbon alone, to the irritation of eye, nose, and throat by sul- nitrogen dioxide, and to carbon which had fur dioxide, formaldehyde, and other gaseous previously been exposed to nitrogen dioxide. pollutants. He stated that around 550 mg of nitrogen LaBelle et al.41 studied the effect of par- dioxide was adsorbed per gram of carbon. ticulate matter on the survival time of mice Samples of air taken from the chamber dur- exposed to formaldehyde, acrolein, and ox- ing the exposure of mice to carbon with ad- ides of nitrogen. The particles used included sorbed nitrogen dioxide indicated that there triethylene glycol, ethylene glycol, mineral was about 25 ppm to 30 ppm free nitrogen oil, glycerin, sodium chloride, two commer- dioxide. Although this is a high concentra- cial filter grades of diatomaceous earth, and tion of nitrogen dioxide, mice exposed to even a commercial silica gel. From theoretical higher concentrations (250 ppm) of nitro- considerations, the probable percent penetra- gen dioxide alone developed pulmonary ede- tion of the upper respiratory tract by vari- ma, but neither single nor repetitive ex- ous gases was calculated. If the gas pene- posure produced parenchympi lung lesions. trated to a greater extent than the particles, Control mice and mice exposed to carbon then adsorption on the particles would de- alone showed no anatomic abnormality of crease the amount of irritant gas reaching the lungs. Mice exposed to the carbon with the lungs and the toxicity would decrease. adsorbed nitrogen dioxide developed focal Such a situation exists with oxides of nitro- destructive pulmonary lesions. The expo- gen. Conversely, if the gas did not readily sures in this group were 6 hours per day, penetrate the upper respiratory tract,. ad- 5 days a week, for 3 months. sorption on small particles would tend to The typical lesions of pneumonitis were carry more gas to the lungs and thus in- observed by Gross et al." in the lungs of crease the toxicity. Such a situation exists hamsters,s rats, and guinea pigs exposed to with formaldehyde. The theoretical calcula- a "sufficiently large number of carbon par- tions coincided with experimental results in ticles with either adsorbed sulfur dioxide or over 70 percent of the gas-particle combina- nitrogen dioxide." Exposure was 8 hours tions. The theory partially explains the po- per day, 5 days per week, for 4 weeks. The tentiation of irritant gases by particulate particle size of the carbon, and the meaning material (often termed a synergistic effect), of the phrase "a sufficiently large number but subsequent research has shown that the of carbon *particles" were not given. There problem is not as simple as had been as- was no record of the amount of either gas sumed, adsorbed by the activated carbon particles. A synergistic effect was reported by Dal- Histologicalsections were from animals hamn and Reidwith ammonia and carbon killed about a month after the end of ex-

185 posure, whereby it is concluded that the le- not by 2.5 -s particles, at concentrations of sions were persistent. They were concen- about 10 mg/m3. With sulfur dioxide 24 and trated in the regiOns of the respiratory bron- with formaldehyde 25 as irritants, decreasing chioles and alveolar dusts and consisted of the concentration of the aerosol, or the total cellular wall thickening. dose of aerosol by shortening the exposure Pattie and Burgess 4 studied the effect of time," decreased the degree of potentiation mixtures of sulfur dioxide and smoke on observed from the addition of sodium chlo- mice and guinea pigs. Their concentrations ride. The hypothesis of LaBelle et a/.0 that of sulfur dioxide were in the range of 2,700 irritant gases with high water solubility mg/m3 to 12,000 mg/m3 (900 ppm to 4,000 would be potentiated by particles did not ppm), and the smoke concentrations were in explain adequately the data obtained. Sul- the range of 50 mg/m3 to 135 mg/m3. Their fur dioxide, formaldehyde, acetic acid, and end point was the dosage required to produce formic acid all have high water solubility, death. With concentrations of this magni- but it was found that the first two were po- tude, the results obtained have little appli- tentiated by sodium chloride 23' 24 and that cability to air pollution criteria. Although the latter two were not.". 27 Although both they found that the lethality of mixtures of sulfur dioxide and formaldehyde were po- sulfur dioxide and smoke was greater than tentiated by sodium chloride, there are dif- the lethality of the sulfur dioxide alone, they ferences which suggest that the guiding considered the effect to be a simple additive mechanism in the case of sulfur dioxide may one resulting from the action of smoke in be chemical change and for formaldehyde blocking the bronchi and alveoli. may involve surface adsorption." Salem and Cullumbine 5 studied the effect Another paper 2, examines further the ef- of kerosene smoke on the acute toxicity of fect of various physical and chemical factors sulfuric acid, sulfur dioxide, acrolein, and on the potentiation of sulfur dioxide by par- acetaldehyde in guinea pigs, mice, and rab- ticulate material. The degree of potentiation bits. As in the work by Pattie and Burgess,* observed could be correlated to some extent the concentrations were many magnitudes with the solubility of sulfur dioxide in the above those found in air pollution episodes. solutions of sodium chloride, potassium chlo- The administration of smoke prior to the ride, and ammonium thiocyanate. exposure to the irritant substances did not Aerosols of soluble salts of ferrous iron, alter the toxicity, although the -effects of manganese, and vanadium, which had been smoke on the toxicity of the irritantswere shown by Johnstone and co-workers 45' 46 to highly variable when the two agentswere be capable of catalyzing the conversion of given simultaneously. In guinea pigs, the sulfur dioxide to sulfuric acid when they toxicity of sulfuric acid was increased by the were present as nuclei of fog droplets, presence of smoke, the toxicity of acetalde- showed a major potentiating action where hyde and sulfur dioxide was decreased, and present at concentrations of about 1 mg/m3. the toxicity of acrolein was unchanged.. In On the other hand, dry manganese dioxide, mice, the toxicity of sulfur dioxidewas in- activated or spectrographic carbon, iron ox- creased, while that of acetaldehyde andacro- ide fume, open hearth dust, and triphenyl lein was decreased. In rabbits, the toxicity phosphate did not alter the response even of acrolein and acetaldehyde was decreased when present in concentrations of 8 mg/m3 by the smoke. The end point in allcases was to 10 mg/m3. the mean fatal dose. It is clear from the data presented 22 that A series of studies of the effect of hygro- all particulate material does not potentiate scopic particles on physiological response to the response to sulfur dioxide any more than irritants has been undertaken by Amdur,22-27 one particulate (sodium chloride) has po- using the pulmonary flow resistance tech- tentiated the response to all irritantgases nique.It was found initially that there- tested. Both solubility of sulfur dioxide in sponse to sulfur dioxide was potentiated by a droplet and catalytic oxidation to sulfuric particles of sodium chloride below 1it, but144.acid play a major role in the observed poten- 186 4 r.,.. tiation of sulfur dioxide by certain particu- incidence, and the word "carcinogen' will .late matter. be used without qualification.. A portion of the organic material present D.CARCINOGENESIS. in the atmosphere as suspended particles (Table 1-2) may be carcinogenic, and carci- 1.Carcinogens nogenic materials have been identified in the The incidence of cancer, and the insidious atmosphere of virtually all large cities in nature of the onset of malignant cell activity, which studies have been conducted. The in- together make essential the utmost effort in complete combustion of organic matter is one determining whether factors associated with of the major sources of such substances; the air pollution can lead to increased occurrence photochemical reaction products of aliphatic of lung cancer in susceptible individuals, or and aromatic constituents of gasoline in the to increased susceptibility to cancer in the presence of the atmospheric gases also pos- population at large. In various parts of the sess some potency for generating tumors ex- world, and especially in the United States, perimentally. the relative mortality due to lung cancer has Chemical and physical studies of polluted been increasing!? Furthermore, urban resi- urban air have been paralleled by carcino- dents exhibit a greater liability to the de- genic investigations using skin painting, sub- velopment of lung cancer than do those liv- cutaneous injection, and inhalationtech- ing in rural areas," and data from several niques.The carcinogenicity (as measured investigations suggest that the epidemiologi- by these techniques) of extracts of mate- cal association between urban residence and rials collected. from air as well as such pol- lung cancerisofpathogenetic signifi- lutant sources as chimney soots, road dusts, cance.45-51 The association between lung can- and vehicular exhausts, has been established cer and cigarette smoking is too well docu- by many investigators.It should be noted mented to need further amplification here. first that, in many cases, use was made of There is, however, one feature common to mite (A-strain) particularly susceptible to both air pollution and cigarette smoking tumor development; and second, only two of studies which should be emphasized. In no the studies, those involving ozonized gaso- case, for the reasons explained in the intro- line, used inhalation as a route df adminis- duction to this chapter, has a suspected car- tration. The observed response in the case , cinogen in fact been demonstrated experi- of A-strain mice inhaling ozonized gasoline mentally to produce a lung tumor in man, was the relatively rapid development of mul- although the epidemiological considerations tiple adenomas in the lung which, although to be developed in the next chapter may well tumors, are not malignant.52 show a significant association between the More recently, sequamous cell cancers of suspected material and cancer. Thus, sub- the lung were induced in C57 black mice fol- stances such as the polynuclear aromatic hy- lowing infection with influenza virus and drocarbons (of which benzo (a) pyrene, BaP, continuous exposure to an aerosol of ozon- is the prime example) may or may not pro- ized gasoline. The tumors produced were 1 duce lung cancer in man. However, they histologically identical with those observed do increase tumor incidence in laboratory most frequently in man." animals and, in addition, have produced ma- Measurable concentrations of inorganic lignancies when in combination with spe- substances, such as metal dusts and asbestos, ,g cific particles or viral infection. The mini- demonstrated to be occupationilly associated mum, possible risk should always be taken- with increased liability to lung cancer de-

with a potentially toxic substance whose ef- velopment, are also emitted into the atmo- A fect may appear after a long period of la- sphere.54-50Additional laboratory experi- tency. The bulk of the. ensuing discussion is mentation is needed to'verify such carcino- therefore based on the hypothesis that carci- genic potential relative to interacting effects nogens effective in animals may be siva& and respective ambient atmospheric concen- cant in increasing human malignant tumortrations.

187 2. Polynuclear Aromatic Hydrocarbonsas total aromatic hydrocarbon contentof air Carcinogens in PollutedAtmospheres pollutants of nine American cities. Polynuclear aromatic hydrocarbonsare The physical stability of aerosolsin pol- commonly regarded with extremesuspicion luted atmospheres has already beendescribed as possible carcinogens, and muchof the in general terms (Chapter 1).Chemically, experimental work performed hasconcerned benzo(a)pyrene seems to be relativelystable these compounds. This sectiondeals with and, even in thepresence of a strongly oxi- the presence and stabilityof the hydrocar- dizing atmosphere, suchas that found in bons in the atmosphere, andwith their elu- photochemical smog characteristicof Los tion from soots on which theymay be ad- Angeles, the rate of disappearanceof ben- sorbed. zo(a)pyrene is smaller than that ofmany Theconcentrationofbenzo (a) pyrene other hydrocarbons. Table 10-443shows the (BaP) as a representativecarcinogenic hy- destruction under certain conditionsof ex- drocarbon in selected urbanand nonurban posure of various polynuclear aromatic hy- areas within the United States is shownin drocarbons present in air. Table 10-2; 61 in Table 10-3,62the benzo(a)- Polynuclear aromatic hydrocarbonsmay pyrene content is given as a fractionof the exist in the atmosphere adsorbedon carrier particles as well as in their freestate. As Table was mentioned in Section C-2, in the respira- 10-2. BENZO(A)PYRENE CONaSNTRA- tory system, particle size influences TIONS IN SEVERAL URBANAND NONI.THBAN the rate AREAS. and extent of elution of adsorbateseither into the macrophages,or onto the respira- plg BaP/1000m° air tory epithelium. Polycyclic aromatichydro- State carbons cannot be readily eluted Urban from soots Nonurban of very small particle size; in fact,particles Alabama with an average diameter of lessthan 0.04N. 24 0.076 will remove these compounds Indiana 39 1.8 from their im- Maryland 14 0.70 - mediate environment because ofhigh sur- Missouri 54 0.025 face adsorption. Particles above0.04-p. aver- North Carolina 39 0.26 age size range will generally release adsorbed Oregon 8 0.01 aromatic Pennsylvania polycyclic hydrocarbons inthe 61 1.9 presence of appropriate solvents, which in- South Carolina 24 1.1 clude plasma and cytoplasmicproteins. As particle size increases, release becomesmore rapid and greater in extent. The Table 10-3.BENZO(A)PYRENE ASA FRACTION elution of OF THE TOTAL AROMATICHYDROCARBON polycyclic aromatic hydrocarbons from0.5-p. CONTENT OF SEVERAL URBANATMOS- soot particles after incubation withplasma PHERES for various time intervals is shownin Table 10-5." BaP fraction of In studies on skin carcinogenesis,Falk City total aromatic hydrocarbon, pg/g and Steiner,66using commercial carbon blacks, related the biological Lot 19 Lot 20 activity of adsorbed carcinogens to the sizeof the soot Atlanta 1,800 1,900 particle and the presence of naturaleluting Birmingham 2,300 3,400 substances at the site of deposition.They Cincinnati 2,800 5,200 advanced the principles of naturaland con- Detroit 3,800 4,600 _ ditional carcinogens, of solvent elution,and Los Angeles 660 260 i of adsorption, to explain Nashville 5,900 4,900 some clinical and New Orleans 2,100 1,600 epidemiological observations of humanskin Philadelphia 2,500 and lung cancers, and of the roleof preced- San Francisco 680 290 ing pathological lesions inpredisposing to pulmonary tumors. 188 Table 10-4.EFFECT OF VARIOUS CONDITIONS OF EXPOSURE ON THE DESTRUCTION OF SOME POLYNUCLEAR AROMATIC HYDROCARBONS

Percent destroyed

Pure unadsorbed Adsorbed on soot

Hydrocarbons By air By air By smog By air in dark in light in light in ligh .v By smog Hours

24 48 24 48 1 48 1

Compound X 100 100 100 12 72 Anthanthrene 44 49 42 44 5 55 Phenanthrene 39 61 34 60 Pyrene 24 43 20 42 83 1 58 Fluoranthene 17 20 16 24 59 4 59 3, 4 Benzpyrene 0 0 21 22 50 10 18 1, 2 Banzpyrene 7 51

1, 12 Benzperylene 0 0 _ 0 0 27 0 67 Coronene 0 0 0 0 5 Chrysene 0 0 11 0 15

The interaction o_ f carcinogens with other could induce cancers in this system." Ac- particulate agents has been studied toxico- ording to Saffiotti et at." the increased ac- logically, utilizing laboratory animals. Ex- tion for the carcinogen is thought to be periments have shown that the addition of brought about by its adherence to the fine seemingly inert particulates Jo carcinogens inert particulate which in turn carries it results in the production of malignant neo- through the respiratory bronchioles and plasms in the lung.Pylev 66 produced an alveoli into the lung parenchyma. The carci- appreciable incidence of lung cancers in rats nogens may then be eluted from the particu- by the intratracheal administration of 9, lates and spread diffusely to reach the target 10-dimethy1-1, 2 benzathracene (DMBA) in- tissue. They infer that there is also a re- corporated with india ink in a 4-percent duction in the speed in which BaP is re- casein solution, whereas Gricute " was un- moved from the respiratory tract brought successful with the same material when it about by the hermatite dust. Shabad et al.'1 was suspended only in physiological saline. have reported that when india ink was in- Saffiotti el.'" has produced a variety of ma- cluded in the inoculum, BaP was eliminated lignant tumors in the lungs of hamsters by more slowly from the lung. One must con- intratracheal instillation of saline suspen- sider the possibility that the carrier material sions of BaP ground together with hematite itself might be contributing some effect. (Fe208) as a carrier dust in amounts equiv- Faulds and Stewart" reported increased in- alent to 3 mg of each chemical, once weekly cidence of carcinoma in the : lungs of hema- for 15 injections. Not only was a high in- tite miners. However, it is difficult to assess cidence of lung cancers produced but also the exact role of iron in such a complicated these lung cancers mimicked all the various exposure situation, since silica and other cell types seen in human cancers, i.e., squa- dusts are certain to be present.Bonser mous cell carcinoma, anaplastic carcinoma, et al." suggest. that iron oxide may play adeno-carcinoma, and even tracheal cancers. role in converting the fibrogenic effect of Dose-responseeffects. were suggested, as silica into a carcinogenic process. Haddow were indications that a single high dose and Horning " have reported that the car-

f 139 1.47 Table 10-5.PERCENTAGE RECOVERY OF POLYNUCLEAR AROMATICHYDROCARBONS FROM 0.5A SOOT PARTICLES AND FROM PLASMA AFTER INCUBATIONWITH PLASMA FOR VARYING PERIODS.

Incubation time. hours Compound Concentration, Fraction 1.6 16 96 192 vg /mg Soot Percentage recovery

Pyrene 8.4 Soot 9 34 9 6 Plasma 81 61 60 61 Total 90 96 69 67 1-7 Fluoranthrene 1.0 Soot trace present 0 present Plasma 100 present present present Total 100

Compound-X 2.8 Soot 0 trace 0 0 Plasma 100 98 present 89 Total 100 98 89

1,2-k mpyrene 2.9 Soot trace 17 0 0 Plasma 62 41 21 21 Total 62 68 21 21

8,4-Benzpyrene 1.7 Soot 18 41 6 18 Plasma 82 69 28 18 Total 100 100 29 86

1,12-Benzperylene 9.2 Soot 81 67 6 11 Plasma 66 88 16 18 Total 97 100 20 24

Anthanthrene 2.4 Soot 26 64 trace 18 Plasma 64 88 17 18 Total 79 87 17- 20

Coronene 10.0 Soot 40 66 12 15 Plasma 86 26 8 10 Total 76 92 20 26 cinogenic action of an iron-dextran complex mas. In mature mice injected subcutaneous- cannot be entirely explained by the dextran ly with carcinogens, the tumors usually de- content alone. Consequently, iron cannot be velop in the vicinity of the site of inocula- excluded as a possible contributing factor tion. However, in newborn mice, the tumors or cofactor in cancer production. Epstein frequently develop at distal points suchas et a1.75 have recently applied methods em- the liver, lungs, or lymph nodes. ploying the injection of crude benzene-solu- More recently, Kuschner '76has deinon- ble extracts of atmospheric particulate into strated the interaction of a known carcino- suckling mice. The total dosages adminis- gen with the gaseous air pollutant, SO,. In- tered ranged from 5 to 55 mg and produced halation exposures of rats indicated that SO2, a high incidence of tumors in surviving mice alone, produced proliferative and metaplastic as compared to controls. At 50 weeks post- changes in the bronchial epithelium; benzo- inoculation, a variety of tumors was evi- (a) pyrene, alone, failed to cause the develop- dent, the most significant being lymphomas, ment of tumors, but the inhalation of benzo- hepatomas, and multiple pulmonary adeno- (a) pyrene in the presence of SO2 caused the development of bronchogenic squamous cell Table 10-6.DISTRIBUTION OF LUNG CANCER carcinoma. BY SITE OF ORIGIN

3.Pathology of Carcinogenesis Percentage Site of origin of Ratherlittleexperimental evidenceis incidence available on the pathology of carcinogenesis following exposure to air pollutants; much Main bronchus (including intermediate) 11 more experimentation has been carried out Lobar bronchus 29 Segmental bronchus 29 in relation to smoking and lung cancer. The Segmental area (i.e., peripheral tumor) 31 results of the extensive work on the latter topic by Auerbach et al." are reported briefly because of the possible similarities between E.SUMMARY carcinogenic mechanisms in cigarette smok- This chapter reviews toxicological studies ing and air pollution. The authors describe of various types of particulate matter known a series of changes which are characterized to be present in ambient atmospheres. These by loss of cilia, increase in the number of studies are primarily concerned with the cell rows, and the presence of atypical cells disciplinary areas of pathology, physiology, in the thickened epitheliuni. Their findings and carcinogenesis. In addition, the mecha- suggest a progression of changes from ini- nisms of the toxicological action of particu- tial goblet cell hyperplasia to metaplasia, late matter are discussed and considerations metaplasia with atypism, carcinoma in situ, concerning mixtures of irritant gases and and invasive cancer. Their data further sup- particulate matter are given proper empha- port the epidemiologic observation of a dose sis. To date, studies utilizing laboratory ani- response to cigarette smoke. Carnes 78 also mals have, in the main, been concerned with observed a clear and pronounced association levels of particulate materials far in excess betvveen the extent of epithelial change and of ambient concentrations. Although direct exposure to pollutants, and emphasized the extrapolations from the laboratory animal similarity of epithelial changes in man to to man are impossible, animal experimenta- "hyperplasia and other changes in the bron- tion is useful and necessary for rapidly de- chial epithelium of mice." Indistinguishable fining the toxicological mechanisms of ac- histologic counterparts can be identified in tion and for pinpointing the primary bio- both man and experimental animals. logical systems affected by a specific particu- The sequence of hyperplasia, metaplasia, late material alone or in the presence of an metaplasia with atypical change, cancer in irritant gas. Findings obtained from animal situ, and invasive cancer is likely to occur experimentation can be tested under com- first at sites of impingement and particulate munity conditions with human populations retention. In experiments with animals, par- via epidemiological studies. ticle deposition and retention occur,most Particulate matter may exert a toxic effect readily in the more distal segments of the via one or more of three mechanisms: tracheobronchialtree, a result which appeared at first to be incompatible with early 1. The particle may be intrinsically clinical and pathologic observations that pri- . toxic due to its inherent chemical mary bronchial carcinomas originated chiefly and/or physical characteristics; in the main stem bronchi. Early clinical ob- 2. The particle may interfere with one servations, however, included a majority of or more of the clearance mechanisms cases in which tumor size was great and in the respiratory tract; point of origin was difficult to ascertain, and 3. The particle may act as a carrier of recent reports question the concept that most an adsorbed toxic substance. primary lung cancers are hilar or central in The last of these mechanisms can lead to a origin. For example, Table 10-6 shows the "potentiating" effect in which particles con- .distribution of lung cancer by sites of origin taining an adsorbed toxic substance increase given by Kotin." the physiological response to the adsorbed I. 1 141 substance to a level above that which one 9. Schnurer, L."Effects of Inhalation of Smoke would expect if the substance were present from Common Fuels." Am. J. Public Health, in the absence of the particle.Conversely, Vol. 27, pp. 1010-1022, 1937. 10. Pattie, R. E., Wedd, C. D., and Burgess, F. "The prior exposure of an animal to particulate Acute Toxic Effects of Black Smoke." Brit. J. matter can sometimes afford a degree of pro- Ind. Med., Vol. 16, pp. 216-220, 1959. tection to subsequent exposure to irritant 11. Nau, C. A., Neal, J., and Stembridge, V. "A gases. Particle size and dust load both con- Study of the Physiological Effects of Carbon tribute toward determining the toxicity of Black. I. Ingestion." Arch. Ind. Health, Vol. 17, pp. 21-28, 1958. any specific chemical substances: reduction 12. Nau, C. A., Neal, J., and Shembridge, V. "A in particle size generally increases toxicity, Study of the Physiological Effects of Carbon while even an "inert" particle may elicit Black. H. Skin Contact."Arch. Ind. Health, toxic responses when present in high enough Vol. 18, pp. 511-520, 1958. concentrations. Finally, it has been clearly 13. Nau, C. A., Neal, J., and Stembridge, V. "A Study of the Physiological Effects of Carbon demonstrated that a number of substances Black. III. Adsorption and Elution Potentials." (metal dusts, asbestos, polynuclear aromatic Arch. Environ. Health, Vol. 1, pp. 512-533, 1960. hydrocarbons, etc.) known to be carcinogenic 14. Nau, C. A., Neal, J., Stembridge, V., and Cooley, in animals are present in polluted atmos- R. N. "Physiological Effects of Carbon Black. pheres. When linked with urban-rural dif- IV. Inhalation." Arch. Environ. Health, Vol. 4, ferences in lung cancer frequency revealed pp. 15-431, 1962. 15. Vintinner, F. J. and Baetjer, A. M. "Effect of from epidemiologic investigations, this evi- Bituminous Coal Dust and Smoke on the Lungs. dence indicates that such substances in urban - Animal Exptriments." Arch. Ind. Hyg., Vol. 4, polluted atmospheres may be potentialcar- pp. 206-216, 1961. cinogens for the exposed human population. 16. Baetjer, A. M. and Vintinner, F. J. "The Ef- fects of 'Silica and Feldspar Dusts on Suscepti- bilityto Lobar Pneumonia.Animal Experi- F.REFERENCES ments." J. Ind. Hyg. Toxicol., Vol. 26, pp. 191- 1. Stokinger, H. E. and Coffin, D. L. 108, 1944. "Biologic 17. Baetjer, A. M. "The Effect of Port...and Cement Effects of Air Pollutants." In :Air Pollution, Vol. I, A. C. 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Ind. Hyg. Assoc. J., Vol. 4. Pattie, R. E. and Burgess, F. "Toxic Effects of 24, pp. 326-333, 1963. Mixtures of Sulphur Dioxide and Smoke with 21. Amdur, M. 0., Silverman, L., and Drinker, P. Air." J. Pathol-Bacterial., Vol. 73, pp. 411-419, 1957. "Inhalation of Sulfuric Acid Mist by Human Subjects." Arch. Ind. Hyg., Vol. 6, pp. 305-313, 5. Salem, H. and Cullumbine, H. "Kerosene Smoke 1962. and Atmospheric Pollutants."Arch. Environ. Health, Vol. 2, pp. 641-647, 1961. 22. Amudr, M. 0. and Underhill, D. W. "The Effect of Various Aerosols on the Response of Guinea 6. Wagner, W. D., Dobrogorski, 0. J., and Stokin- Pigs to Sulfur Dioxide." Arch. Environ. Health, ger, H. E. "Antagonistic Action of Oil Mists Vol. 16, pp. 460-468, 1968. on Air Pollutants." Arch. Environ. Health, Vol. 23. Amdur, M. 0. "The Influence of Aerosols upon 2, pp. 523-534, 1961. the Respiratory Response of Guinea Pigs to 7. Amdur, M. 0. and Devir, S. E.Unpublished Sulfur Dioxide." Am. Ind. Hyg. Quart., Vol. data. 18, pp. 149-155, 1957. 8. Schnurer, L. and Haythorn, S. R. "The Effects 24. Amdur, M. 0. "The Effect of Aerosols on the of Coal Smoke of Known Compositionon the Response to Irritant Gases." In: Inhaled Par- Lungs of Animals." AM. J. Pathol., Vol. 13, ticles and Vapours, Vol. I, C. N. Davies (ed.), pp. 799-810, 1937. Pergamon Press, London, pp. 281-292, 1961. 142 25. Amdur, M. 0. "The Response of Guinea Pigs to 40. Dautrebande,L., Shaver,J., and Capps, R. Inhalation of Formaldehyde and Formic Acid "Studies on Aerosols. XI. Influence of Particu- Alone and with a Sodium Chloride Aerosol." late Matter on Eye Irritation Produced by Vola- Intern. J. Air Pollution, Vol. 3, pp. 201-220, tile Irritants and Importance of Particle Size 1960. inConnectionwith Atmospheric Pollution." 26. Amdur, M. 0. "The Physiological Response of Arch. Intern. Pharmacodyn., Vol. 85, pp. 17-48, Guinea Pigs to Atmospheric Pollutants."In- 1951. tern. J. Air Pollution, Vol. 1, pp. 170-183, 1959. 41. LaBelle, C. W., Long, J. E., and Christofano, 27. Amdur, M. 0."The Respiratory Response of E. E. "Synergistic Effects of Aerosols. Particu- Guinea Pigs to the Inhalation of Acetic Vapor." lates as Carriers of Toxic Vapors." Arch. Ind. Am. Ind. Hyg. Assoc. J., Vol. 22, pp. 1-5, 1961. Health, Vol. 11, pp. 297-304, 1955. 28. Nadel, J. A., Corn, M., Zwi, S., Flesch, J., and 42. Dalhamn, T. and Reid, L. "Ciliary Activity and Graf, P. "Location and Mechanism of Airway Histologic Observations in the Trachea after Constriction after Inhalation of Histamine Aero- Exposure to Ammonia and Carbon Particles." sol and. Inorganic Sulfate Aerosol." In: Inhaled In: Inhaled Particles and Vapours, Vol. II, C. Particles and Vapours, Vol. II, C. N. Davies N. Davies (ed.), Pergamon, London, 1967, pp. (ed.), Pergamon Press, London, pp. 55-67, 1967. 299-306. 29. Dautrebande,L."Microaerosols." Academic 43. Boren, H. C. "Carbon as a Carrier Mechanism Press, New York, 1962. for Irritant Gases."Arch.Environ. Health, 30. DuBois, A. D. and Dautrebande, L. "Acute Ef- Vol. 8, pp. 119-124, 1964. fects of Breathing Inert Dust Particles and of 44. Gross, P., Rinehart, W. E., and DeTreville, R. T. Carbachol Aerosol on the" Mechanical CLarac- "The Pulmonary Reactions to Toxic Gases." teristics of the Lungs in Man. Changes in Re- Am. Ind. Hyg. Assoc. J., Vol. 27, pp. 315-321, sponse after Inhaling Sympathomimetic Aero- 1967. sols."J. Clin. Invest., Vol. 37, pp. 1746-1755, 45. Johnstone, H. F. and Coughanowr, D. R. "Ab- 1958. sorption of Sulfur Dioxide from Air Oxida- 31. Amdur, M. 0. "The Effect of High Flow-Re- tion in Drops Containing Dissolved Catalysts." sistance on the Response of Guinea Pigs to Ir- Ind. Eng. Chem., Vol. 50, pp. 1169-1172, 1958. ritants." Am. Ind. Hyg. Assoc. J., Vol. 25, pp. 46. Johnstone, J. F. and Moll, A. J. "Formation of 564-568, 1964. Sulfuric Acid in Fogs from Sulfur Dioxide in 32. McDermott, M. "Acute Respiratory Effects of Air Containing Nuclei of Manganese and Iron the Inhalation of Coal Dust Particles." J. Phys- Salts." Preprint. (Presented at the 136th Amer- iol., Vol. 162, p. 53, 1962. ican Chemical Society meeting, Atlantic City, 33. Amdur, M. 0. and Creasia, D. A. "The Irri- New Jersey, 1959.) tant Potency of M-Terphenyl of Different Par- 47. Pascua, M. "Increased Mortality from Cancer ticle Sizes." Am. Ind. Hyg. Assoc. J., Vol. 27, of Respiratory System."Bull. World Health pp. 349-352, 1966. Organ., Vol. 12, pp. 687. 704, 1955. 34. Tremer, H., Falk, H. L, and Kotin, P. "Effect 48. Kotin, P. and Falk, H. L. "The Role and Action of Air Pollutants on Ciliated Mucus-Secreting of Environmental Agents in the Pathogenesis Epithelium." J. Natl. Cancer Inst., Vol. 23, pp. of Lung Cancer:I. Air Pollutants."Cancer, 979-997, 1959. Vol. 12, pp. 147-163, 1959. 35. Stockinger, H. E. "Toxicologic Perspective in 49. Kotin, P. "The Role of Atmospheric Pollution Planning Air Pollution Studies." Am. J. Public in the Pathogenesis of Pulmonary Cancer. A Health, Vol. 13, pp. 742-751, 1953. Review." Cancer Res., Vol. 16, pp. 375-393, 1956. 36. Vorwald, A. J."Effect of Inert Dusts in Air 50. Cambell, J. A. "Cancer of the Skin and In- Pollution."In: U.S. Technical Conference on crease in Incidence of Primary Tumors of Lung Air Pollution, McGraw-Hill, New York, 1952, in Mice Exposed to Dust Obtained from Tarred pp. 485-488. Roads." Brit. J. Exptl. Pathol., Vol. 15, pp. 287- 37. Schrenk, H. H. "Causes, Constituents and Physi- 294, 1934. cal Effects of Smog Involved in Specific Dra- 51. Clemo, G. R., Miller, E. C., and Pybus, F. C. matic Effects."Arch. In Hyg., Vol. 1, pp. "The Carcinogenic Action of City Smoke." Brit. 189-194, 1950. J. Cancer, Vol. 9, pp. 137-141, 1955. 38. Dautrebande, L."Bases experimentales de la 52. Kotin, P. and Falk, H. L."Experimental In- protection contre les gas de combat." J. Ducu! duction of Pulmonary Tumors in Strain A Mice lot (Belgium), 1939. Following Their Exposure to an Atmosphere of 39. Dautrebande, L. and Capps, R."Studies on Ozonized Gasoline." Cancer, Vol. 9, pp. 910-917, Aerosols. IX. Enhancement of Irritating Effects 1956. of Various Substances in the Eye, Nose, and 53. Kotin, P. and Wiseley, D. V. "Production of Throat by Particulate Matter and Liquid Aero- Lung Cancer in Mice by Inhalation Exposure sols in Connection with Pollution of the Atmo- to Influenza Virus and Aerosols of Hydrocar- sphere." Arch. Intern. Pharmacodyn., Vol. 82, bons." Progr. Exptl. Tumor Res., Vol. 3, pp. 505-527, 1950. 186-215, 1963.

51 143 54. Hueper, W. C. "A Quest into Environmental omogenic Action of Urethane."Vopr. Onkol., Causes of Cancer of the Lung." U.S. Dept. of Vol. 2, pp. 671-678, 1956.(In Russian) Health, Education, and Welfare, Public Health 68. Saffiotti, U., Cefis, F., Kolb, L. H., and Grote, Service, Public Health Monograph 36, 1956. M. J."Intratracheal Injections of Particulate 55. Lynch, J. R. and Ayer, H. E. "Measurement of Carcinogens into Hamster Lungs."Proc. Am. Asbestos Exposure." J. Occupat. Med., Vol. 10, Assoc. Cancer Res., Vol. 4, p. 59, 1963. pp. 21-24, 1968.. 69. Saffiotti, U., Cefis, F., and Kolb, L. H. "Broncho- 56. Balzer, J. L."Industrial Hygiene for Indus- genic Carcinoma Induction by Particulate Car- trial Workers." J. Occupat. Med., Vol. 10, pp. cinogens."Proc. Am. Assoc. Cancer Res., Vol. 25-31, 1968. 5, p. 55, 1964. 57. Tabershaw, I. R. "Asbestos 'as an Environmen- 70. Saffiotti, U., Cefis, F., Kolb, L. H., and Shubik, tal Hazard."J. Occupat. Med., Vol.10, pp. P. "Experimental Studies of the Conditions of 32-37, 1968: Exposure to Carcinogens for Lung Cancer In- 58. Cralley, L. J., Cooper, W. C., Lainhart, W. S., duction."J. Air Pollution Control Assoc., Vol. and Brown, M. C. "Research on Health Effects 15, pp. 23-25, 1965. of Asbestos." J. Occupat. Med., Vol. 10, pp. 38- 71. Shabad, L. M., Pylev, L. N., and Kolesnichenko, 41, 1968. T. S. "Importance of the Deposition of Carci- 59. Cralley, L. J., Keenan, R. G., Lynch, J. R., and nogens for Cancer Induction in Lung Tissue." Lainhart, W. S."Source and Identification of J. Natl. Cancer Inst., Vol. 33, pp. 135-141, 1964. Respirable Fibers."Am. Ind. Hyg. Assoc. J., 72. Faulds, J. S. "Carcinoma of the Lung in Hema- Vol. 29, pp. 129-135, 1968. tite Miners." J. Pathol. Bacteriol., Vol. 72, pp. 60. Cralley, L. J., Keenan, R. G., Kuepel, R. E., and 353-366, 1956. Lynch, J. R. "Characterization and Solubility 73. Bonser, G. M., Faulds, J. S., and Stewart, M. J. ofMetals Associated with Asbestos Fibers." "Occupational Cancer of the Urinary Bladder Am. Ind Hyg. Assoc. J., Vol. 29, p. 125, 1968. in Dyestuffs Operatives and of the Lung in 61. Sawicki, E Elbert, W. C., Hauser, T. R., Fox, Asbestos Textile Workers and Iron-Ore Miners." F. T., and Stanley, T. W. "Benzo(a)pyrene Con- Am. J. Clin. Pathol., Vol. 25, pp. 126-134, 1955. tent of the Air of American Commu'.; ties." Ind. 74. Haddow, A. and Horning, E. S. "On the Car- Hyg. J., Vol. 21, pp. 443-451, 1960. cinogenicityof an Irondextran Complex."J. 62. Hueber, W. C., Kotin, P., Tabor, E. C., Payne, Natl. Cancer Inst., Vol. 24, pp. 109-147, ,1960. W. W., Falk, H., and Sawicki, E. "Carcinogenic 75. Epstein, S. S., Joshi, S., Andrea, J., Mantel, N., Bioassays of Air Pollutants."A.M.A. Arch. Sawicki, E., Stanley, T., and Tabor, E. C. "The of Pathology, Vol. 74, pp. 89-115, 1962. Carcinogenicity of Organic Particulate Pollut- 63. Falk, H. L., Markul, I., and Kotin, P."Aro- ants in Urban Air after Administration of Trace matic Hydrocarbons. IV. Their Fate Following Quantities to Neonatal Mice." Nature, Vol. 212, Emission into the Atmosphere and Exposure to pp. 1305-1307, 1966. Washed Air and Synthetic Smog." A.M.A. Arch. 76. Kuschner, M. "The J. Burns Amberson Lecture : Ind. Health, Vol. 13, pp. 13-17, 1956. The Causes of Lung Cancer." Am. Rev. Res- 64. Falk, H. L., Miller, A., and Kotin, P. "Elution pirat. Diseases, Vol. 98, pp. 573-590, 1968. of 3, 4-Benzopyrene and Related Hydrocarbons 77. Auerbach, 0., Stout, A. P., Hammond, E. C., and from Soots by Plasma Proteins."Science, Vol. Barfinkel, L. "Smoking Habits and Age in Re- 127, pp. 474-475, 1958. lation to Pulmonary Changes. Rupture of Al- 65. Falk, H. L. and Steiner, P. E. "The Identifica- veolar Septums, Fibrosis, and Thickening of tion of Aromatic Polycyclic Hydrocarbons in Walls of Small Arteries and Arterioles." New Engl. J. Med., Vol. 269, pp. 1045-1054, 1963. Carbon Blacks." Cancer Res, Vol. 12, pp. 30-39, 1952. 78. Carnes, W. H. "The Respiratory Epithelium in Relation to Selected Diseases and Environmen- 66. Pylev, L. N. "Experimental Production of Pul- tal Factors."(Report to the U.S. Dept. of monary Cancer in Rats by Intratracheal Intro- Health; Education, and Welfare) April 1964. duction of 9, 10- dimethyl -1, 2-Benzanthracene." Biull. Eksp. Biol. Med., Vol. 52, pp. 99-102, 1961. 79. Kotin, P. and Falk, H. L. "Carcinogenesis of the (In Russian) Lung: Environmental and Host Factors." In: The Lung.Williams and Wilkins Co., Balti- 67. Greezuitay, L. A. "On the Mechanism of Blast- more, Maryland, pp. 203-225, 1968. Chapter 11

EPIDEMIOLOGICALAPPRAISAL OF PARTICULATE MATTER Table of Contents Page A. INTRODUCTION 148 B. APPLICATION OF EPIDEMIOLOGY TO AIR POLLUTION 148 1. Indices 148 2. Cautions 148 C. INDICES OF HUMAN RESPONSE: THE EPIDEMIOLOGIC STUDIES 150 1. Acute Episodes 150 a. Mortality 150 b. Morbidity 154 2. Chronic (Long-Term) Air Pollution 156 a. Day-to-Day Variations in Mortality and Morbidity 156 b. Geographical Variation in Mortality 156 1. Studies Based on Available Data 156 2. Special Studies Involving the Collection of New Data 158 c. Geographic Variations in MorbiditySpecial Studies 161 d. MorbidityIncapacity for Work 164 3. Studies of Children 165 4. Studies of Pulmonary Function 167 5. Studies of Panels of Bronchitic Patients 168 D. SUMMARY 169 E. REFERENCES. -176

List of Figures Figure 11-1Mortality Figures for the January 1956 and December 1957Smog "Episodes" in London 151 11-2Mortality and Air Pollution in Greater London duringthe Winter of 1958-1959 152 11-3 Death Rates and Air Pollution Levels in Dublin, Ireland, for1938- 1949 155 11-4 Average Annual Death Rate from all Causes 160 11-5 Average Annual Death Rate from Asthma, Bronchitis,or Emphy- sema Indicated on the Death Certificate 160 11-6 Average Annual Death Rate from Gastric Cancer 161 11-7 Age-Standardized Morbidity Rateper 1,000 for Three Diseases .in Japan 162 11-8Effect on Bronchitis Patients of High Pollution Levels (January 1954) 169

Y 146 154 List of Tables

Table _ Pope 11-1Pollution Levels in Salford (seasonal daily averages) 159 11-2Average Annual Death Rates Per 1,000 Population From AllCauses According to Economic and Particluate Levels, and Age: White Males 50-69. Years of Age, Buffalo and Environs,1959-1961 159 11-3Average Annual Death Rates Per 100,000 Population from Chronic Respiratory Disease According to Economic and ParticulateLevels, and Age: White Males 50-69 Years, Buffalo and Environs,1959- 1961 160 11-4Average Annual Death Rates Per 100,000 Population forGastric Cancer According to Economic and Particulate Levels: WhiteMales 50-69 Years of Age, Buffalo and Environs,1959-1961 161 11-5Response of Telephone Workers in the U.K. and the U.S.A. toAir Pollution 163 11-6Summary Table of Epidemiological Studies 171

.155 t I e 147 Chapter 11 EPIDEMIOLOGICAL APPRAISAL OF PARTICULATE MATTER

A. INTRODUCTION life," of major segments of the worldpopu- Health effects produced by atmospheric lation. particulate matter are discussed in this chap- Several health indices are described in ter in terms of epidemiologic studies. Be- Section B-1;certainprecautions which cause particulate matter tends to occur in should be observed in the application of epi- the same kinds of polluted atmosphere as demiologic methods to air quality criteria sulfur oxides, few epidemiologic studies have are suggested in Section B-2. The studies been able adequately to differentiate the ef- themselves are listed in Section C, accord- fects of two pollutants. It follows, therefore, ing to the index employed. that the studies presented in this chapter are frequently identical with those described in B.APPLICATION OF EPIDEMIOLOGY the companion document, Air Quality Cri- TO AIR POLLUTION STUDIES teria for Sulfur Oxides. 1. Indices' Epidemiologicstudies, asdistinguished from toxicologic or experimental studies, Various indices of health may be used for analyze the effects of pollution from ambi- correlation with air pollution by the oxides ent exposure on groups of people living in of sulfur. Among the possible indicesare: a community. Such studies have the advan- 1. mortality (greater than expected) tage of examining illness where it occurs (i) deaths from all causes naturally, rather than in a laboratory, but (ii)deaths from specific causes carry the disadvantage of not being able to (iii) deaths among the differentage control precisely all the factors of possible and sex groups importance. Nevertheless, the preparation of air quality criteria must rest on epidemio- 2. morbidity logic studies because of the very severe limi- (i)incidence of diseasechronic tations of toxicologic and industrial studies bronchitis, pulmonary emphy- for this purpose. Other countries, notably sema, diffuse interstitial pneu- the Netherlands and Sweden, have based monitis, cancer of respiratory their air quality criteria solely on epidemio- tract, disease of remote organ logic studies. (e.g., gastrointestinal, ophthal- In determining whether or notan asso- mic, and cardiovascularsys- ciation is causal, consideration must be given tems) to several aspects of association which in- (ii)prevalence of diseasessame clude strength, consistency, specificity, tem- examples as for "incidence" porality, biological gradient, plausibility,co- (iii) prevalence of respiratorysymp- herence, and analogy.' A judgment of the toms (e.g., changes in quality value of an epidemiologic study requiresan and/orquantityofsputum understanding of these aspects. Many types production) of epidemiologic evidence suggest that air (iv) exacerbation of diseasesrhi- pollution may exert considerable influenceon norrhea, asthma, tracheobron- health, as well as on the "satisfaction with chitis, and chronic illness, and : 148 .,156 enhancement of infection: pne- urements to enhance detection, while long- umonia, sinusitis, otitis, mas- term chronic processes may be adequately toiditis related to long-term sampling intervals. Air (v)changes in clinical conditions pollution measurements useful in studies of (e.g., bronchitic patients) acute health effects are becoming available; 3. changes in various aspects of lung a less satisfactory situation exists for the function long-term effects studied. (i)ventilatory functiondecrease In many instances the possible role of cig- in peak flow rate, decrease in arette smoking has not been considered. It is spirometric volumes,impair- expected that future epidemiologic studies ment of flow-volume relation- involving adults will routinely collect data on ship, and increased airway re- smoking habits of the study group. Other sistance factors are significantly related to respiratory disease. These include occupational and (ii)blood/gas distributionimpair- other past exposures; infections, past and ment of lung-gas distribution present; and allergy and heredity. (iii) blood/gasexchangeimpair- Few or no epidemiologic studies have been ment of pulmonary blood-gas possible where the pollution challenge has exchange been limited to particulate matter, unaccom- (iv) increased work of breathing panied by significant amounts of other pol- Definitions of the various disease states are lutant substances. Indeed, most of the availa- to be found in the glossary; most of the pul- ble conclusions link particulate levels with monary function methods have been men- those of concurrently measured sulfur di- tioned in Chapters 9 and 10.. oxide; some studies attempt statistical sep- The manner of presentation of the state of aration of the culpability of one factor from epidemiological knowledge of effects of par- the other in the effects cited. ticulate matter in the ambient atmosphere In seeking the possible effects on popula- when accompanied by the oxides of sulfur is tions resident in areas of differing air pollu- outlined in the Table of Contents. tion, factors such as smoking, type and conditions of employment, ethnic group, and mobil- 2.Cautions ity in response to experienced irritation or In the first place, as discussed in Chapter disease have sometimes been considered.. 1, methods of measurement vary from coun- There has, however, been a minimum of at- try to country and place to place. Results tention paid to the indoor or domestic envi- from the high volume sampler and the results ronments and their potential contribution. from smoke stain calibration are very dis Measurement of such indoor exposures might similar. Also, coh values cannot be compared be difficult, but omission of the information with µg /m'. could well modify the appraisal of the im- Secondly, particle size plays an important portance of particulate pollution. part in the appropriateness of the measuring Toxicologic studies indicate a specific po- technique as it does in determining the site tential of some particulate materials to pro- and effectiveness of deposition in the respirse duce human responses. The levels used in tory tract. (See Chapter 9.) However, size toxicologic studies are far higher than those distribution of particles has nearly always found in the communities in the epidemio- been ignored in field studies. logic studies under review. Thus the actual Thirdly, pollution and health indices are responsibility of "particulate matter" for not always measured over the same time the community responses is uncertain, and periods. It is to be hoped that the pollution it is sometimes necessary to invoke addition- levels cited bear some relation to those extant al concepts; for example, the idea of syn- during the time when the chronic disease ergism with other known or unkown ambient states were developing. Further, acute effects pollutants, or the idea that particulate matter require frequent short-term pollution mess- is but an index of availability of some other

149 substance (s) which are fully responsible for must consider especially the impact of air the effects reported. pollution on the "most sensitive" responders. Over a short period of time, mortality Many factors seem to enhance susceptibility fluctuates considerably, and only a syste- or sensitivity to air pollution. These include matic, long-term approach will allow a valid being at the extremes of age (i.e., infants and determination of the real role of air pollution. the very old) ; having pre-existing chronic Cassell et al.2 have reviewed the problem of respiratory disease (e.g., pulmonary emphy- detecting peaks in mortality and relatingsema or chronic bronchitis); having pre- them to any single variable. The danger with existing cardiovascular disease (functional episodic studies is that short-term fluctuation capacity not defined) ; regularly smoking cig- in the death rate, when picked to coincide arettes; or living in overcrowded or depressed with an air pollution incident, may appear socioeconomic strata. Some of these factors to be causally related; in the long term, how- have been singled out for attention in the ever, numerous other unassociated peaks are references to be cited, and the level of pol- found in both the death rates and the air pollutant said to have an "effect" may take cog- lution levels. nizance of such special sensitivity. Specific substances encountered as respira- The effects discussed are related insofaras ble particles, and associated with disease en- possible to specific pollution over specific time tities (beryllium, asbestos, arsenic, vanadi- intervals; it must be emphasized that lower um, lead, airborne pathogens, etc.) are not values by no means imply a "no effect" level assessed in this report. They deserve consid- of the pollutants. eration, however, as exemplars of the modes of response of which the human is capable, C. INDICES OF HUMAN RESPONSE: and which may delay or confound the recog- THE EPIDEMIOLOGIC STUDIES nition of the importance of "particulate matter" inhalation. The demonstration of the 1.Acute Episodes importance of aerodyriamic behavior rather a. Mortality than ofmass or particle dimension for both In conurbations, such as London, New impingement and retention of asbestos is York, Chicago, and Detroit, it has beenpos- striking. Long-delayed effects from relatively sible to observe deviations from the moving brief community dispersion exposures toas- averages of deaths during various seasons, bestos and beryllium are significant(see and to relate such deviations to the coincident Chapter 10). Furthermore, penetration of period levels of air pollutants., "poorly cleared" particles of asbestos tore- In writing about the Mease Valley episode mote body sites suggests complex body trans- in 1936, Firket stated that if there werea port mechanisms, differing organ or. tissue similar phenomenon in London, some 3,200 sensitivities, and the need for evaluation of death might occur 1.3 Unfortunately, hewas as yet untested relationships between disease quite accurate iri his estimate since, in Decem- entities and respirable offenders. These mod- ber 1952, the world's most disastroussmog els confer some sense of urgency to establish- incident occurred in London, causing about ing the relationships of human disease and 4,000excess,deaths throughout the Greater dysfunction to air pollution by "generalpar- London area. Marked increases were noted ticulate matter." in both respiratory and cardiovascular deaths The concept of "susceptible population" (and for almost every cause except traffic demands consideration. Human responses to accidents; presumably the smog was too thick toxicants, and to community air pollution, for people to drive). Since some of the diseas- show wide variations, which contribute inno es such as lung cancer and tuberculosis were small way to the difficulty in assessing ina obviously existent before the pollutionep- general manner the effects of pollutants. isode, much of the effect of the fogwas clear- Since air quality criteria must, unless other- ly to hasten the death of people whowere wise specified, consider "all" population rath- already ill. Detailed investigations were made er than just major segments of it, studies of 1,280 post-mortem reports ofpersons who 150 -158 had died before, during, or shortly after the well as the differential relationship between episode. No fatalities were found which could sulfur dioxide and smoke levels and the re- not have been explained by previous respira- sulting mortality. tory or cardiovascular lesions. In this episode Gore and Shaddick s and Burgess and as in others, the elderly and persons with pre- Shaddickreviewed acute "fog" episodes existing pulmonary and cardiac disease were which occurred in London in 1954, 1955, 1956 most susceptible. (January and Decmeber), and 1957 (Decem- A number of investigations have analyzed ber), in terms of excess mortality above a and compared the various London episodes. moving average, related to the mean of daily The report by Brasser et al.° appears to cover readings at seven stations for smoke and SO2. all the episodes and to present a detailed Figure 11-1 shows mortality figures for the analysis of each of these episodes, pointing January 1956 and December 1957 episodes. out the importance of the duration of the Somewhat differing patterns of onset of maximum values. More recently, Joosting mortality rise, of age of population suffering has examined the relationship between the most heavily, of deaths related to bronchitis duration of maximum values of sulfur dioxide and to other respiratory diseases, and of total and smoke during air pollution episodes, as deaths, were noted in these acute episodes.

JANUARY, 1956 DECEMBER. 1957

ALL AGES

70+ YEARS

0 69 YEARS

25 305 10 15

DEC. JAN. NOV. DEC.

FUMES 11-1. Mortality Figures for the January 1966 and December 1967 Smog "Episodes" in London .° (The figure shows the increase in numbers of deaths during sjn g, episodes" (shaded periods),' especially in the older age group.)

151

347.335 P.0.369.461REV. REPRO . Common to them, however, were elevations sociation between mean daily sufur dioxide in the mean daily levels of SO2 and smoke, levels and deaths (all causes). Bronchitis measured at seven different stations, from deaths showed a lower correlation with the two to four times the winter average levels; pollution level, and the authors suggest the "effects" were estimated at 2,000 pg/m3 black need for consideration of effects of air pol- suspended matter together with 0.4 ppm lution on patients with cardiovascular di- (1,145 pg /me) SO2 (representing all acidic sease. In addition, excess deaths have been gases). Deaths ascribed to bronchitis were related to increases (on the day preceding materially affected, but deaths due to other death) of mean daily black suspended matter causes also increased. Deaths appeared to by more than 200 pg/m3, and rises inmean begin to increase before the onset of theep- daily SO2 of more than about 75 pg/m3 (2.5 isodes; during the episodes, of course, they pphm). In a later paper," dataare shown to increased substantially. Scott 10 observeda suggest an increase in mortality from all similar relationship, for similar periods of causes, and of respiratory and cardiac mor- "fog," with "effective pollutant" levels at bidity, associated with levels of smoke about seven different stations in London of 2,000 1,000 pg/m3, and SO2 concentrations of 715 pg/m3 for smoke and 0.4 ppm for SO2. There pg/m3 (25 pphm). This "effect" is properly was a sharp impact on the elderly and the related to abrupt rises in the concentration of greatest proportionate rise, forcause of smoke and/or S02, with perhapsa continuum death, in bronchitic.s. of effects at lower levels. Since thesemeas- Martin and Bradley 11correlateddaily urements were obtained at a single point in mortality (all causes) and daily bronchitis Central London, it should be presumed thata mortality with mean daily black suSpended relatively wide range of values around these matter (see Figure 11-2) measured atseven levels actually contributed to the mortality locations in London for the winter of 1958- statistics which were correlated. A reanalysis 1959, and also found a significant positiveas- by Lawther 13of these mortality studies

80-- 20 60 >- Ors 10 AN, I cc : 20 c z 0 IF z x 0 " oz eso o ro-00% el.. 0 0 C 5 (3 0. a% 0 >- 01 0-- 0 s

CORRELATION COEFFICIENT rw 0.613 CORRELATION COEFFICIENT re, 0.411

1.0 1.2 1.4 1,6 1.8 2.0 2.2 2.4 1.0 1.2 1.4 1.6 1.8 2.0 2.22.4

(LOGI° OF BLACK SUSPENDED MATTER CONCENTRATION) FIGURE11-2. Mortality and Air Pollution in Greater Londonduring the Winter of 1958-1959." (The figure shows increased mortality due to "all causes"! ,nd to bronchitisduring a period of high pollution.) 152 1.160 places the mortality "effect" at about 750 pg/ ter related to the amount of excess mortality, m3 for smoke and about 715 µg /me (0.25 other factors must be considered as possibly ppm) for SO2. hosting states that the maxi- also reducing the number of deaths. Since mum sulfur dioxideconcentration above 1952, a great deal of publicity has been given which significant correlation occurs with to the harmful effects of smog, and more sus- death and disease is 400 µg/m3 to 500µg /m' ceptible individuals have been encouraged to (0.15 ppm to 0.19. pppm)* when there is a use masks and filters and stay indoors. In high soot content. addition, when episodes come close together, The Dutch report on sulfur dioxide,° which a large number of susceptible individuals discusses in detail seven air pollution episodes might not accumulate, since some are killed in London, states that in the December 1956 off each time. An effect as large as that seen episode, 400 excess deaths, or 25, percent in the first incident would not, therefore, be above expected, were observed in Greater expected. London at maximum 24-hour levels of 1,200 The number of deaths in New York City pg/m8 for smoke and 1,100 pg/m3 (0.41 was reviewed for excess mortality in rela- ppm) * for SO2. The report also notes that in tion to the air pollution episode of November January 1959, 200 excess deaths were observ- 1953, by Greenburg et al." Excess deaths ed in Greater London, or 10 percent above were related to elevations of concentrations expectedmortality,at a levelof 1,200 of sulfur dioxide and suspended particles. µg /m' for smoke and 800 µg /m' (0.30 ppm) * Average daily suspended particulate matter for SO2. The episodes all took place during measured in Central Park was in excess of winter; cold weather seems to have been an 5.0 coh units, while the SO2 rose from the important feature of London air pollution New York City average ranges of 430 µg /m3 mortality. to 570 µg /m' (0.15 ppm to 0.20 ppm) to a In Martin's review 12 in 1964 of daily mor- maximum level of 2,460 µg /ml (0.86 ppm). tality in London during the winters of 1958- For this episode, there was a "lag effect," 1959 and 1959-1960, he concluded: "From and distribution of excess deaths among all the data it would be difficult to fix any thresh- age groups was noted. The number of deaths, old value below which levels of air pollution although not showing the marked rise seen might be regarded as safe." However, his in some of the London episodes, was above review included data with smoke concentra- average for comparable periods in other tions ranging upward from 500 lAg/m3and ac- years during and immediately after the in- companied by sulfur dioxide concentrations cident. For the November 15 to 24, 1953, of about 400 µg /m' (0.14 ppm) and above. period, the average number of deaths per As a result of smoke control regulations, day was 244, whereas during the three years the particle content of London air has steadi- preceding and following 1953, the average ly decreased since the 1950's, but the sulfur was 224 deaths per day for the same calen- dioxide concentrations have not decreased dar period. proportionately. At the same measuring sites A later episode (1962) was studied," But as in 1952, sulfur dioxide was actually slight- Greenburg et al. did not discern an excess ly higher in the 1962 episode than in that of mortality. However, McCarron and Brad- 1952, buC smoke levels were considerably ley," reviewing episodes in New York City lower.Also, as Brasser et at.° have noted in November and December of 1962, January there was only one day of maximum pollution and February of 1963, and February and values in 1962 as contrasted with the 2 days March of 1964, compared 24-hour average of maximum pollution in December 1952. levels of various pollutants with New York Although the smoke levels appear to be bet- City mortality figures, employing daily deviations from a 15-day moving average; the measurements were performed at a single *SO, is converted from ppm to pg/m8 in the Dutch report by using the equivalency 2,700 pg/ne.-1 ppm; station in lower Manhattan and fluctuations Scott apparently used 2,860 pg/nei1 ppm; this re- in the values at this station were known. to port uses 2,860 pg/m8.-.1 ppm. correlate well with those at another station

4 158 6.5 miles away. Excess deaths on December companying. SO2 greater than 285µg /m' 1, 1962, followed a daily average SO2 concen- (0.1 ppm) ; the measurements were made at tration of 2,060 µg /m° (0.72 ppm) and smoke a single station in the central commercial

shade in excess of 6 coh units, during a pe- area of the city. - riod of atmospheric inversion and low- When a marked increase in air pollution ground-wind speed. The increased death is associated with a sudden dramatic rise in rates were shared by the 45-to-64 age group, the death rate or illness rate lasting for,a as well as by the age group over 65. In a few days and both return to normal shortly later episode (January 7, 1963) associated thereafter, a causal relationship is strongly with an SO2 concentration of 1,715 µg /m' suggested. Sudden changes in weather, how- (0.6 ppm) and smoke shade at 6 coh units, ever, which may have caused the air pollu- there was a peak of death rate apparently tion incident, must be considered as another superimposed upon an elevated death rate possible cause of the death rate increase. average due to the presence of influenza vi- Over the years, a number of such acute epi- rus in the community. Two further epi sodes have been reported, and thereseems sodes 'a. '7 also suggest the relationship of little doubt that air pollution was thecause. excess deaths to abrupt rises in both SO2 and The British studies presented in thissec- suspended smoke at times of air stagnation. ,tion suggest that excess mortality,a small An example of the inherent danger of re- rise in the daily death rate, is detectable in lating mortality peaks to air pollution is large populations if the concentrations of shown by Leonard et atliin,the Dublin stud- smoke and SO2 rise abruptly to levels above ies. During the war and post-war years of 750 µg /m3 and 715 µg /m, (about 0.25 ppm) 1941 to 1947, pot was burned as the main respectively; the same effects are noted in fuel rather than coal, and air pollution (as American cities for SO2 concentrations above measured by particle concentrations) was 1,700 µg /m' (about 0.6 ppm) and a "smoke markedly decreased. Sulfur dioxide levels shade" of 6 coh units. The major targetsare varied in a manner similar to those of sus- the aged population, patients with chronic ob- pended particulate matter. The winter peaks structive pulmonary disease, and patients in death, however, were unaffected, and thus with cardiac disease. A more distinct rise do not seem to be related to air pollution. in deaths is noted generally when particulate When coal again became available in 1948, matter reaches about 1,200 pigim3 forone the air pollution levels rose with no appar- day and sulfur dioxide levels exceed 1,000 ent effect on the death rate (see Figure 11- µg/m, (about 0.35 ppm). Daily concentra- 3). Unfortunately, it is not possible to assess tions of suspended particulates exceeding the effects of changing medical practices and 2,000 pg/m3 for one day in conjunction with the advent of antibiotics for use in treat- levels of sulfur dioxide inexcess of 1,500 ing respiratory diseases on these data. µg /m' ( ppm) appear to be associated In Detroit '° a rise in infant mortality and with an increase in the death rate of 20per- deaths in cancer patients occurring overa cent or more over baseline levels. 3-day period accompanied a rise in the 3- b. Morbidity day mean suspended particulate matter for The acute episodes have- resulted in sub- the same period above 200 µg /m'accom- stantial increases in illness.Thus a sur- panied by an SO2 maximum of 2,860 pgjma vey in of emergency clinics at major New (1.0 ppm) (September 1952). This is not York City hospitals in November 1953 indi- believed to be related to the cold temper- cated a rise in visits for upper respiratory atures which have characterized the London infections and cardiac diseases in both chil- episodes. dren and adults in all of the four hospitals In Osaka, Japan, Watanabe 2° reported on studied. "Smoke shade" was close to 3 coh excess deaths in a December 1962 smog epi- units, and sulfur dioxide concentrations had sode. There were 60 excess deaths related not yet exceeded 715 µg /ms. (0.25 ppm) when to mean daily concentrations of suspended hospital admissions clearly rose." matter greater than 1,000 pg/m3, with ac- Again, the number of emergency clinic 700 A 70 ; II 60 it- elDEATHS FROM1 RESPIRATORY DISEASES 50 400 I / POLLUTION BY SUSPENDED MATTER 11IIII 40 4 ISI IiI1 5 30 n s Aa I t I A sII i 1 0 1II I % I I l i 1s II I it I I I 1 i oI t 1 1 1 s I t I 1 20 100 I so I I 1 I It ; I ' ' 1i 4.4" / I / t 1 .... i i I I i I ' - iist. $ I I II I1 1 1 1 1 1 1 .. 1 1 . I I I I I t 1 I /I 1 i 1 II i 1 I .. I i 1 1 l ,0 0 , FEB JUNE JAN JUNE JAN JUNE JAN JUNE JAN JUNE1938 JAN JUNE JAN JUNE JAN JUNE JAN JUNE JAN JUNE JAN JUNE JAN JUNE 1939 1940 1941 1942 1943 1944 1945 . 1946 1947 1948 1949 FIGURE 11-3. Death Rates and Air Pollution* Levels in Dublin, Ireland for 1938 - 1949." YEAR ii,1144:.i.'i ';i-:.Aii;,4.*izi. .i4;,..i4A4'...,=- '. . ..+I-4,S:.,FA:-.,1:;:...:...... i+V.iYl..,.,:.24;.....N::' . visits for bronchitis and asthma atseven piratory and cardiac morbidity daily in large New York City hospitals Lon- was examined don, Martin 12 examined deiriations inmor- during the Thanksgiving 1966 air pollution bidity from a 15-day movingaverage in Lon- episode.22 There was a rise in the number don during the winters of 1958-1959and of such visits on the third' day ofthe epi- 1959-1960. Both smoke and sulfur dioxide sode, among patientsage 45 and over, at concentrations appear to be about equally three of the seven hospitals investigated. Un- related to morbidity rates, anda definite ex- fortunately, the Thanksgiving holidaygreat- cess in morbidity seemed to exist as it did for ly complicated evaluation of theemergency mortality,. though there wasa somewhat clinic visits over the holiday period." greater degree of irregularity. In the investigation of the London episode An approach similar to Martin's, but limit- of December 1952, information on illness ed to observations on mortality,was used by was collected from as many sourcesas pos- McCarroll and Bradley 16 in New York City. sible including sickness claims, applications Covering a 3-year period (1962-1964) they for hospital admission, pneumonianotifica- examined a number of peaks in New York tions and records of physicians. Theanaly- City mortality associated with periods of sis demonstrated a real and importantin- high air pollution. There are examples given crease in morbidity, though there wassome where sulfur dioxide and smoke shadeap- indication that the increase in illnesswas pear to be related to mortality. The authors not as large proportionatelyas the increase present other episodes, however, where the in deaths and the effects were not so sudden relationship to air pollution is not nearlyas in producing a marked_rise inthe early days clear, although the death rate* fluctuates to of the episode. In a number ofother severe even higher peaks. Reference to this analy- London episodes the increase inmorbidity sis has already been made in.our discussion put a considerable strainon the health serv- of the data on episodes in Section B.1. ices. McCarroll et al.22 studied residents of.a These episodes reflect results whichfall New York City housing project, using into Level IV of the World Health week- Organiza- ly questionnaires. Exact levels of airpol- tion's"guidesto air quality." 23These lutants which could be used for establish- "guides," equivalent inusage to our term.ment of air quality criteria were not given; "criteria," cover sets of concentrationsand however, the data indicate that sulfur diox- exposure times at which specified types of ide rather than particulate matterwas asso- effects are notedor at which no effect is ciated with eye irritation. Syinptoms of noted. Level IV includes "concentrationsand cough were also shown to be related toair exposure times at and above which there is pollution but were not well differentiated be- likely to be acute illnessor death in sus- tween association with particles and sulfur ceptible groups of the population." dioxide. The particular time-series analysis 2.Chronic (LongTerin) Air Pollution used with these data is not well known,and Kurland 24 has called to our attentionthat the biases inherent in itsuse have not been air pollution episodes repreient,by defini- fully determined. tion, massive, overwhelming, andunusual exposure, and thus the most significant patho- b. Geographical Variations in Mortality logic effects. There isan "iceberg" effect 1. Studies Based on Available Data. in that such data represent the obvious,while Mortality and morbidity statistics eachhave the greater share of the problemremains advantages as well as disadvantages.Rec- submerged. We are dealing withan essen- ords of illness should bemore fruitful in de- tial dose-response situation, theupper limits fining subtle effects, since illness precedes of which are represented by theseepisodes. death and since all illness does notresult in death.Mortality statistics are collected a. Day-to-Day Variations in Mortality and in every country and are available Morbidity for quick tabulation.Unfortunately, the quality of In a systematic approach to analyzinglp4mortality statistics varies. One of the prob- 156 lems is that with the present system of tabu- cess of bronchitis mortality occurred for lating mortality data, a single cause of death clams of area where the average daily smoke must be selected and coded,even. though and SO2 concentrations both exceeded 200 more than one cause may be involved in the pg/A13, Although smoking habits were re- death. The single cause of death designated viewed and were apparently uniform from (e.g., specific chronic respiratory disease) area to area, occupational and domestic in- depends largely on the judgment of the at- door environmental exposures were not con- tending physician and has little, if any, rela- sidered. The pollutant values selected for tion to epidemiologic use. While contributing the correlations do not cover the same time causes of death appear on the death cer- period as the mortality figures. tificate, they are not reflected in summary A series of papers by Stocks' et at.,27-31 tabulations. The coding of only the "under -. related atmospheric pollution in urban and lying" cause of death minimizes the impor- rural localities with mortality due to lung tance of such diseases as emphysema which cancer, bronchitis, and pneumonia. Stand- often appear on the death certificate as con- ardized mortality ratios apparently refer to tributory or associated causes of death.25 the period 1950 to 1953 for bronchitis and Almost all studies of the effects of long- pneumonia and to the period 1950 to 1954 term exposure on death rates compare the for lung cancer. Lung cancer mortality was rate in one area with that in another. Mor- found to be strongly correlated with smoke tality as well as morbidity studies are ham- density in the atmosphere for 26 areas of pered by the possibility of differences other northern England and Wales, for 45 districts than air pollution existing between the areas, of Lancaster and Yorkshire, and for 30 such as social class, occupation, age, and sex county boroughs.(Similar but weaker cor- composition of the population, and cigarette relations were observed within Greater Lon- smoking. Assuming that almost all deaths don.) Further, social differences in the popu- are recorded and tabulated, comparison of lations concerned only partially explain this total mortality rates(i.e., deaths from all correlation.Bronchitis and pneumonia for causes) obviates the bias of diagnostic selec- males and bronchitis for females similarly tion, but does not lessen the chances of other showed strong correlations with smoke den- associated factors having caused the differ- sity in the atmosphere. Cancers of the stom- ence. ach and intestine in the county boroughs Buck and Brown 26 reported in 1964 'the were also related significantly to smoke con- relation of standardized mortality ratios for centrations, and other relationships are de- the 5-year period 1955-1959 to four vari- scribed for various areas of the country. It ables: daily smoke and SO2 concentrations is, however, difficult to extract specific quan- for March 1962 (presumed representative of titative "effect" levels for smoke or the other the study period), population density in 1961, pollutants studied. Papers 30. 31 describe the and a social index of 1951. The studies in- statistical elimination applied to develop sig- volved populations in 214 areas of the United nificant correlations of spectographic analy- Kingdom (19 London boroughs, 49 county ses of 13 trace, elements with mortality rates. boroughs, 70 boroughs, 61 urban districts, Reanalysis of the data by Anderson 52 con- and 15 rural districts). firmed the importance of smoke levels, as Statistical studies indicate that bronchitis well as social and population parameters, to mortality had a significant positive associa- mortality from lung cancer; vanadium is also tion with both the smoke and the SO2 con- identified as an important independent concentrations encountered in these residential tributor to lung cancer, female cancer, and;,, areas, and also with social index. The stand- pneumonia mortalities. ardized mortality rates for lung cancer were In summary, the results of this analysis not, in general, significantly associated with of long-term mortality indicate effects which smoke or SO2 concentrations in the residen- would coincide with Level III of the World tial areas. Examination of the tables given Health Organization's "guides to air qual- by Buck and Brown suggests that the ex- 23 Level III is defined as "concentrations t U1 157 5

and exposure times at and above whichthere cer and bronchitis mortality rates between is likely to be impairment of vital physiologic the two localities. Occupationalexposure to rJ functions or changes thatmay lead to chronic pollution was then taken into account inthe diseases or shortening of life." analysis. The conclusion was that there is 2. Special Studies Involving the Collection an association between the degree of air of New Data.In 1964, also, Wickenand pollution and the incidence of lungcancer Buck 33 reported on a study of bronchitisand and bronchitis mortality in the twoareas of lung cancer mortality in sixareas of North- the Eston urban district. Though both sul- east England, one in Eston, another inStock- fur dioxide and smoke values andconcen- ton and four in rural districts. Thedeaths trations are furnished in the report and the covered the period 1952 to 1962. Thesurvey effects apparently cannot be separated, Gras- of decedents with cause of death frombron- ser et al.6 apparently have used the sulfur chitis or lung cancerwas matched against dioxide concentrationas the more relevant the survey of decedents withcause of death measure of this study. from nonrespiratory disease controlledfor The community of Salfordwas classified age and sex; the basis for the diagnostic into three pollution areas by Burn and Pem- classifications was not stated in the report. berton," according to Table 11-1. Fivesam- Personal interviews were carriedout with pling stations in the areawere employed. next of kin. Personal interviews ofa ran- Despite the closeness of theranges of values, dom sample of householdswere also con- a high rate of bronchitis mortality, of lung ducted to obtain sex, age, smoking habitsand cancer mortality, and of deaths from all occupation of the population at risk, theliv- causes, was observed in the high, compared ing population. The survey of decedentswas to the lower pollution wards. Itappears (see carried out between January andOctober Section C-4) that there was alsoan increased 1963; the survey of the living populationwas rate of bronchitis morbidity in the highly carried out between December 1963and polluted wards. March 1964.c.iSmoke and sulfur dioxidecon- Winkelstein et al.35-37 analyzed pollution centrations were measured in the Estonur- effects in a group of studies made ban district. One year's aerometric in the data was Buffalo, New York, area. In July of1961, obtained. The study was excellent inprin- 21. air sampling stationswere set up in and ciple though, unfortunately, sulfurdioxide. around the city of Buffalo, and dailyvalues and particulate valueswere available only for suspended particulates, dustfall, for the Eston urban district. and oxides of sulfur were taken until Juneof 1963. Eston, itself, as a sub-study,was subdi- Suspended particulate levelswere used as vided into North Eaton and SouthEston. the index of air pollution. On thebasis of North Eston containsor lies near heavy in- the measurements, the studyarea was di- dustrial plants, whereas South Estonis a vided into. four contiguousareas 'according residential area.During the period May to their levels of air pollution. Level1 was 1963 to April 1964, mean weekly observa- less than 80 pg /m3 (2-yr. geometricmean) ; tions of the sulfur dioxide and smokecon- level 2, 80 pg /me to 100 pg/m3;level 3, centrations were carried out in two sitesin 100 pg/ma to 135 pg/ma; and level 4,greater North Eston and one station in SouthEaton. than 135 µg /me. Each areawas also divided Smoke values were 160 pg/m3 and 80 µg /ma into five economic groupings. Mortalityfig- for North and South Eston respectively.The ures for the area were taken from the period sulfur dioxide value in North Estonon the 1959 to 1961, with the 1960census provid- yearly average was' 115 pg/ma (0.040ppm) ing the population basis. and for South Eston it was 74 ,:g /ma (0.026 Annual death rates per 100,000popula- ppm). The deaths studied occurredbetween tion for (1) all causes of death; (2) 1952 and 1962. Adjustments chronic were made for respiratorydisease;(3)malignant neo- differences in age composition, smokinghab- plasms of the bronchus, trachea,and lung; its, and social class, and these were'insuffi- and (4) gastric carcinomawere related to cient to explain the differences in lungcan- the four areas of air pollution intensityand 158 1 J4166 Table 11 -1. POLLUTION LEVELS IN SALFORD (SEASONAL DAILY AVERAGES)"

SO2 µg /m' Deaths Smoke pg/m observed x 100 Pollution area (ppm in parentheses) expected classification All Lung Winter Summer Winter Summer causes Bronchitis cancer

High 680 270 716 266 106 128 124 (0.25) (0.09) Intermediate 490 170 460 200 100 97 84 (0.16) (0.07) Low 450 170. 340 146 90 52 79 (0.12) (0.06)

Note: The data in the original report show SO: concentrations in parts per hundred million (pphm). to the socioeconomic levels of the deceased. established with suspended particulate levels Among white males between 50 and 69 and totalmortality, and mortality from years of age, the death rate from all causes chronic respiratory disease, regardless of was 20 per 1,000 in the area with the least the economic level of the deceased. More- suspended particulates (less than 80 pg/m3). over, a positive correlation was established It was 20 percent higher in the next most between suspended particulate levels and gas- polluted area (between 80 pg/m3 and 100 tric cancer that appeared to be independent pg/m3) and twice as high in the most pol- of economic 'status. It should be noted, how- luted area (more than 135 pg/m3). See Table ever, that this study did not take into ac- 11-2 and Figure 114. count the smoking habits of the deceased. Among white males between 50 and 69 Among white males and females between years of age, the death rate from chronic 50 and 69 years of age, the death rate from respiratory disease was 42 per 100,000 popu- gastric carcinoma was 27 per 100,000 population for those living in the area with the lation for those living in the area with the leastsuspendedparticulates,40percent least suspended particulates, half again as higher for those living in the next most high for those living in the next most pol- polluted area, and about three times as high luted area, and one and one-half times as for those living in the most polluted area. high for those living in the most polluted See Table 11-3 and Figure 11-5. Suspended area. See Table 11-4 and Figure 11-6. particulate levels did not appear related to The Nashville Air Pollution Study by Zeid- deaths from cancer of the bronchus, trachea, berg et al.?. 39 used sulfation and dustfall or lung. However, positive correlations were data from 123 sampling stations, and sulfur

Table 11-2.AVERAGE ANNUAL DEATH RATES PER 1,000 POPULATION FROM ALL CAUSES ACCORD- ING TO ECONOMIC AND PARTICULATE LEVELS, AND AGE: WHITE MALES, 50-69 YEARS OF AGE, BUFFALO AND ENVIRONS, 1959-1961.

Particulate Level Economic Level 1. (Low) 2 3 .4 (High) Total

1 (low) 36 41- 52 43 2 24 27 30 36 29 8 24 26 33, 25 4 20 22 27 22 5 (high) 17 21 20 19 Total 20 24 31 40 26

159 dioxide concentrations and soiling indices nomic classes, and then further coded by age, from 36 stations. All codable deaths regis- sex, race, and underlying cause of death. tered between 1949 and 1960 (32,067) were Standardized mortality ratios (for total res- then distributed among census tracts rated piratory disease, and for pneumonia, influ- according to high, moderate, and low pollu- enza, bronchitis, emphysema, tuberculosis, tion levels, and upper, middle, and lower eco- and lung and bronchial cancer) were then

140

ao 100

-10 20

0 0 2' 3 4 1 2 3 PARTICULATE LEVELS PARTICULATE LEVELS (all economic levels) (all economic Mveb) FIGURE 11-5.Average Annual Death Rate from Asth- FIGURE11-4.Averave Annual Death Rate from All ma, Bronchitis, or Emphysema Indicated on the Causes. (The graph shows the daath rate per 1,000 Death Certificate. (The graph shows the death population for white males between 60 and 69 years rate per 100,000 population for white males be- of age for four levels of particulate matter, Buffalo tween 60 and 69 years of age for four levels of par- and environs, 1959-1961.) ticulate matter, Buffalo and environs, 1969-1961.)

Table 11-3.AVERAGE ANNUAL DEATH RATES PER 100,000 POPULATION FROMCHRONIC RESPI- RATORY DISEASE ACCORDING TO ECONOMIC AND PARTICULATE LEVELS, AND AGE:WHITE MALES, 50-69 YEARS OF AGE, BUFFALO AND ENVIRONS, 1959-1961.

Particulate Level Economic Level 1 (Low) 2 3 4 (High) Total

1 (low) Oa 126 188 133 2 64 75 96 105 84 3 66 61 103° 64 4 36 47 114 62 5 (high) 42 63 Oa 50 Total 44 62 94 129 72 a Rate based on less than five deaths. rates between 1955 and 1960. For white infant mortality, significant regressions were obtained for sulfation; dustfall (alone, or as an interaction variable) was the most frequently related variable. In the study, account was not taken of smoking habits of the deceased; also, the "middle class" group covered a relatively large segment of the decedents. It is intresting to note that the association between suspended particulate levels and gastric cancer in the Buffalo study which appeared to be independent of economic status was also observedinthe Nashville study."

2 3 4 c. GeographicVariationsin Morbidity (HIGH) Special Studies PARTICULATE LEVELS (economic levels 2, 3, and 4) It has been postulated that the study of records ofillness rather than mortality FIGURE 11-6. Average Annual Death Rate from Gis- tric Cancer. (The graph shows the death rate per -should be more fruitful in defining subtle 100,000 population for white males between 50 and effects, since morbidity is an earlier and 69 years of age for four levels of particulate mat- more sensitive index of deviation from nor- ter, Buffalo and environs, 1959-1961.) mal health. A much larger insult must presumably be given to the body to cause death related to the pollution indices obtained dur- than to cause illnesp.,Routinely collected ing 1959. The statistically significant mor- morbidity data are, however, not generally tality increases were those forall'respira- available. Data may occasionally be obtained tory diseases related to sulfation and soil- from group insurance plans, hospitaladmis- ing; lung and bronchial cancer mortality, and sion records, or existing school records. Since bronchitis and emphysema mortality were such data are usually not collected in a uni- not clearly related. "High" pollution in these form, precise manner, most morbidity stud- studies referred to soiling at more than 1.1 ies require expensive and time-consuming coh units/1,000 linear feet and SO2 concen- field surveys with questionnaires or actual trations of more than about 30 fag/ma (.01 medical examinations of the subjects. ppm). A later paper 40 derived from the same Morbidity studies of adults involving long- study period, analyzed infant and fetal death term exposures are frequently not as useful

Table 11-1.AVERAGE ANNUAL DEATH RATES PER 100,000 POPULATION FOR GASTRIC CANCER ACCORDING TO ECONOMIC AND PARTICULATE LEVELS: WHITE MALES, 50-69 YEARS OF AGE, BUFFALO AND ENVIRONS, 1959-1961. Particulate Level Economic Level 1 (Low) 2 3 4 (High) Total

1 .(low) 0(0) 63(10) 136(8) 77(18) 2 45(5) 41(12) 48(10) 84 (8) 50(35) 8 39(9) 51(6) 51(2) 44(17) 4 15(3) 38(9) 63(5) 33(17) 5 (high) 26(5) 16(3) 0(0) 20(8) Total 26(13) 84(33) 53(31) 42(95) Figures in parentheses indicate numbers of deaths'

?. 161 as desired due to the presence of complicat- tory disease morbidity from the highly in- ing factors such as occupation and smoking. dustrialized (and presumably polluted)areas Accordingly, Anderson 3° has recommended to .the rural areas of Japan. Further,the that children and housewives be usedto de- pulmonarydiseasemorbidityratiowas termine the health effects of air pollution. higher in the industrialized, pollutedareas A study was conducted by Petri lli et a1.41 than... were the ratios for other diseasegroup- in Genoa, Italy, which followedAnderson's m,g& The gradient was not noted for cardio- recommendation. The subjectswere women vascular diseases nor for gastrointestinal over 65 years of age, nonsmokers who had diseases.Unfortunately, specific pollutant lived for a long period in the same area and concentrations are not clearly indicatedto who had no industrial work experience.Eco- accompany these data on morbidity. The nomic and social conditions in theareas of age-standardized morbidity ratesper thou- residence were thus consideredas well as sand for several cities in Japauare shown the levels of pollution in theareas of their in Figure'11 -7. residence. Pollutant measurementswere car- Holland et W." studied the prevalence of ried out between 1954 and 1964 in19 differ- chronic respiratory disease symptomsand ent areas, and morbidity indices.were cal- performance of pulmonary function tests in culated for 1961 and 1962 for thispopula- a comparative study of outdoor telephone tion, which received free medicalcare from workmen in London, in rural England,and the municipality and thereforewas under on the east and west coasts of the United continuous medical observation. Therewas States. Types of occupationalexposure, use a significant correlation between the fre- of cigarettes, and socioeconomic matching quency of bronchitis with mean annual sul- were considered. The annual meanconcen- fur dioxide levels (r =0.98) anda nonsig- tration of suspended particulate matter nificant correlation in for mean annual sus- the British exposures was approximately200 pended matter (r -0.82) andmean annual Fg/m3, and approximately 120µg /m3 in the dustfall (r =0.66). American case. For sulfur dioxide, themean Toyama," in a comprehensive studyof air concentrations were: in London 300 110113 pollution and its health effects inJapan, (-10.1 ppm), in rural areas of England 60 charts the age-standardized morbidityrates µg /m8 (-0.02 ppm), and in the United (per thousand) secured by interviewsurvey States between 30 µg /m' and 120µg /m' in 1961, and describesa gradient of respira- (-0.01 ppm and 0.04 ppm). Persistent

-I RESPIRATORY CARDIOVASCULAR GASTROINTESTINAL

KAWASAKI

YOKOHAMA

FUJINO I 1

I KAINAN -I DAITO

0 10 20 30 o 10 0 10 20 30 RATE PER THOUSAND

FIORE11-7. Age-Standardized Morbidity Rateper 1,000 for Three Types of Diseases in Japan." (The mortality rate for respiratory diseases shows a clear correlation with pollution levels. There isno such clear correlation for cardiovascular or gastrointestinaldisorders.) 162 kv..A70 cough, phlegm, and chest_ illness' episodes and nomic factors were presumed the same, the increased sputum volume were all signifi- occupational exposures were homogenous, cantly more frequent in men (between the and corrections were applied for smoking. ages of 50 and 59) in the London area than There were some physique differences in the in rural England; and pulmonary function rural areas and allowances were made for was poorer in relation to the levels of smoke these in the statistical evaluation. Unfortu- and sulfur dioxide. It is possible, therefore, nately, no quantitative air quality determina- that an increase in smoke concentration from tions accompanied these results. The authors 120 pg/m8 to 200 pg/m3 (with an equivalent nevertheless concluded that the most likely increase in sulfur dioxide level) increases cause of the difference in respiratory mor- the risk to older workers of deteriorated pul- bidity between the men working in Central monary function and increased symptomatol- London and those in the three rural areas ogy of chronic respiratory disease.Table was related to the differences in the local air 11-5 summarizes some of the results ob- pollution. tained. In a group of Canadian veterans studied Holland and Reid " reviewed respiratory by Bates et a relationship between air symptoms, sputum production, and lung pollution and both bronchitis and pulmonary function levels in post office employees both function measurements has been reported. in central London and in peripheral towns. There are, unfortunately, inadequate data Over the age of 50, the London men had more on the levels of smoke, sulfur dioxide, and frequent and more severe respiratory symp- other pollutants, in the four Canadian cities toms, produced more sputum, and had sig- compared, to derive specific relationships be- nificantly lower lung function tests. Socioeco- tween the levels of these pollutants and the

Table 11-5.-RESPONSE OF TELEPHONE WORKERS IN THE U.K. AND U.S.A. TO AIR '?OLLUTION."

United KingdOm United States Baltimore. London Rural Washington San Francisco areas Westchester Los Angeles County

Age Age Age Age Age Age Age Age 40-49 60-69 40-49 60-69 40-49 60-69 40-49 60-69

Number of men examined 118 187 267 159 896 229 861 119 Persistent cough and phlegm (percent) 25.7 88.7 24.0 18.9 22.2 25.8 21.6 24.4 Persistent cough and phlegm and chest illness episode (percent)___ 10.6 10.9 7.5 5.0 6.8 7.0 4.0 7.6 FEV1.0 (liters) mean values: Non smokers 2.8 2.6 8.0 2.8 8.6 8.1 3.7 8.8 Cigarette smokers: 1-14 per day 2.6 2.8 2.8 2.6 8.4 8.0 15-24 per day 2.6 2.2 2.8 2.5 8.2 2.8 8.4 2.8 26 or more per day 2.5 2.1 2.7 2.5 8.2 2.9 Sputum volume 2 cc. or more (percent) 28.9 42.9 22.1 28.5 7.1 10.0 8.6 14.8 Suspended particulate matter, 24 hr (pg/m): Mean 220 200 120. 120 Maximum 4000 8000 500 840 Sulfur dioxide, 24 hr. (pg/In), ppm in parentheses: Mean 290 (0.1) 60 (0.02) 110 (0.04) 80 (0.01) Maximum 8700 (1.8) 740 (0.26) 716 (0.26) 170 (0.06)

168 VyY 471 prevalence or exacerbation of diseaseor the eases were directly correlated with the aero- deterioration of pulmonary function. How- metric parameters. There was no statistical ever, there is an association in the "dirty" evidence of increased respiratory disease cities (Montreal and Toronto)versus the morbidity or morbidity of otherorgans and "clean" cities (Halifax and Winnipeg) of systems. The same qualifications noted for increased prevalence and severity a bron- the mortality data in this study apply to chitis, and poorer pulmonary functionper- these data on morbidity. formance. Anderson and Ferris 46.47 completed a com- d. MorbidityIncapacity for Work parison of respiratory disease incidence and Dohan " reviewed the incidence of res- air pollution in three residentialareas of priatory disease producing absence from Berlin, New Hampshire, by prevalencesur- work in a population of women employed vey.Subjects who were nonsmokers and in several branches of an electronicscom- those who were moderate smokers werespe- pany in the eastern part of the United cifically evaluated. The different levels of States. Pay scales were roughly equivalent air pollution at one or more stations in each and presumptions were made, therefore, that area were recorded in relation to monthly the socioeconomic status and smoking pat- dustfall and to sulfur dioxide concentration. terns were uniform. Air measurements were Prevalence of respiratory disease and pul- made from areas near the town of employ- monary function determinations(FEVI.G ment (for suspended particulate sulfates, ni- and peak expiratory flow rate) were made. trates, copper, zinc, vanadium, nickel, and The mobility of the population, variations acetone-soluble organic matter, as well as of concentrations of pollutants withina given total suspended particulate matter). Ab- area, possible effects from the area of occu- sences for a respiratory illness in excess of 7 pation, and differences in the in-homeen- days were calculable from company-employ- vironment, were considered as contributors ment and health-insurance records. There to the lack of consistent effect on the studied was a significant correlation of respiratory parameters of air pollution.In a later disease absence frequency with theconcen- study'" these authors compared this "pol- tration of suspended particulate sulfates, luted" town in New Hampshire witha con- with 24-hour values measured biweekly; al- trol community in British Columbia and though the level of total suspended particu- again found an obscuring of the effects of air late matter ranged from 100 µg /m3 to 190 pollution on respiratory symptoms and pul- µg /m3 in the various cities, a correlation was monary function performance, suggesting not demonstrated. The implication of the perhaps the overwhelming effect of cigarette significantly correlated datum "suspended smoking in symptom 'production.It should particulate sulfate" is not clear,as it might, be noted, however, that the pollution levels for example, be an index of the community and the ranges were possibly too lowor too fuel consumption or an index of sulfur di- small to show a relationship. oxide irritation. The Nashville air pollution study'-.re- Burn and Pemberton 34 reviewed the in- viewed total morbidity in relation to air pol- creased number of certificates of incapacity lution. A wide matrix of sampling stations issued to workers in Salford in relation to was used to group the residence of individ- smog episodes. When mean daily smoke pol- uals into areas of high, moderate, and low lution, based on data from five sampling pollution according to geometricmean an- stations, exceeded 1,000 µg /ms for 2consecu- nual measurements, and the morbidity data tive days, the number of "bronchitiscer- were secured by home interview. Significant tificates". issued exceeded the expectednum- "direct correlations" of total morbidity with ber by a factor of two, on fouror five oc- levels of pollution (measured by soiling in- casions in 1958. dex and 24-hour sulfur dioxide levels)were During 1961-1962 a study of the inci- observed for individualsover 55 in the mid- dence of incapacity for workwas conducted dle socioeconomic class. Cardiovascular dis- by the British Ministry of Pensions and Na- 164 tional Insurance." The population covered strong time dependence,. and .yearly cyclical was representative of the working popula- behavior; when this factor was removed tion of England and Wales. Rates of sick- there remahled no strong positive relation- ness absence for bronchitis, influenza, arth- ship between respiratory absence and the ritis and rheumatism were related to in- pollution variables studied. Respiratory ill- dices of pollution. There was a significant ness absence rates were at their highest correlation between bronchitis incapacity in level when sulfur dioxide and smoke shade middle-aged men (35-54) and the average levels were both high on cool days; and a seasonal (October through March) levels of lag effect for respiratory absences was not smoke and sulfur dioxide in high-density noted. residential districts; based on 24-hour meas- 3.Studies of Children urements. For Greater London, there was a Comparisons of the prevalence of respira- significantcorrelation between bronchitis tory disease in areas of varying pollution incapacity and both smoke and sulfur di- levels have been made to delineate the role oxide for all age groups taken together, and of air pollution and specific pollutants. A for men aged 35 to 54 and 55 to 59. It is problem common to all the studies is the interesting that there was also more incapac- difficulty in guaranteeing that the areas are ity from arthritis and rheumatism in areas' similar (except for air pollution) in all fac- having heavy smoke pollution. Influenza in- tors that might affect the prevalence of capacity was greater in those areas with disease. higher pollution levels over Great Britain Because studies on adults tend to be com- as a whole but not within the Greater Lon- plicated by smoking habits, changes of oc- don conurbation, nor was there in this lat- cupations, and changes in address over a ter area' any association between pollution period of years, several studies have been and psychosis or psychoneurosis. The low- .directed at effects of air pollution on school est bronchitis inception ratesrelatedto children. The advantages of utilizing chil- smoke levels between 100 ter/m3 and 200 dren for research on the primary etiologic µg /m3 and to sulfur dioxide concentrations effects of air pollution were first noted by between 150 µg /m3 and 250 µg /m3 (0.053 Reid 53 several years ago; Anderson 32 has ppm and 0.081 ppm). The highest values most recently reaffirmed this view. A major related to particulate concentrations of 400 element of concern is that deleterious effects µg /m3 and 400 aims (0.14 ppm) sulfur di- on the respiratory system of very young oxide. children may have an effect on the subse- Verma et al.,52 presented information on quent evolution of the chronic bronchitis syn- illness absences in relation to air pollution. drome in the adult population. Illness data for the employees (males and The relationships of respiratory infections females, ages 16 through 64) of a metro- to long-term residence in specific localities politan New York insurance company were have been studied in England by Douglas obtained through the records of the person- and Waller."Levels of air pollution, in nel department. They included medical his-: terms of domestic coal consumption records, tory, X-ray information, and laboratory re- were used to classify four groups; the auth- sults obtained by the medical department of ors include an evaluation of the validity of the company, and were classified by absences this method at the end of their report. The due to respiratory illness and to nonrespira- histories of 3,866 children born during the tory illness. Mean daily concentrations of first week of March 1946 were followed until air pollution and meteorologic data were se- 1961, when the children were 15 years of cured from the monitoring system of metro- age.Social class composition of these chil- politan New York: smoke shade, sulfur di- dren did not differ significantly from area oxide, and carbon monoxide content were re- to area. Measured concentrations for smoke ported. The data for the 2 years 1965 and and for SO2 in 1962 and 1963 were coin!. 1966 were examined statistically and several pared with the earlier prediction of pollu- conclusions were reached.There was a tion intensity based on the coal consumption

165 data, and indicated an overlap for the greater ranging above 130 µg /m' and SO2 above 130 London area of low and moderate groupings; aims (0.046 ppm). for other areas, the predicted gradient of The lower respiratory tract findings of concentrations was affirmed. Because of the Douglas and Wallerwere confirmed in a age of the subjects, smoking was apparently study by Lunn et al." The patterns ofres- not considered in this evaluation. In 1965, piratory illness in school children of theage 19 percent of the boys and 5 percent of the group 5 to 6 have been studied with ref- girls, aged 11 to 13, smoked at leastone erence to residence in four areas of Sheffield. cigarette a week regularly." Mean daily smoke levels measured in each In the Douglas and Waller study, thegen- of four areas ranged from 97µg /m' in the eration of pollutants in the indoor home en- Vow" area to 301 µg /m' in the "high"area; vironment (e.g., by heating and cooking) SO, concentrations were respectively 123 was not considered.Interviews were con- µg /m' (0.043 ppm) and 275 µg /m' (0.096 ducted with the mothers when the children ppm) in the two areas, during 1963-1964. were 2 and 4 years of age; information was Somewhat lower pollution levelswere noted obtained about upper and lower respiratory the following year, although the gradientbe- illness and recorded hospital admissions for tween the districts was preserved. Ques- these and other causes. Data about colds, tionnaire to the parents, physical examina- coughs, and hospital admissionswere also tion, observation for thepresence of nasal gathered by school doctors at medicalex- discharge, examination of the eardrums, and aminations when the childrenwere 6, 7, 11 recording of both the forced expiratory vol- and 15 years of age. Between theages of ume of 0.75 seconds (FEVo.n) and the 61/2 and 101/2, special records forcauses of forced vital capacity (FVC), were completed school absence exceeding one weekwere re- during each of the summer terms of 1963, viewed with the mothers. A total of 3,131 1964, and 1965. Several socioeconomic fac- families remained in the same pollutionarea tors were compared for the various districts; throughout the first 11 years of this study. smoking was appropriately disregarded for The conclusions of the studywere that upper this age group; internal home environments, respiratory tract infectionswere not related or differences in home heating systems, were to the amount of air pollution, but that lower not reported.The authors conclude that respiratory tract infectionswere. Frequency there is an association with the levels ofat- and severity of lower respiratory tract in- mospheric pollution and chronicupper res- fections increased with the amount of air piratory infections (as indicated by muco- pollution exposure, affecting both boysand purulent nasal discharge, history of three girls, and with no differences detectablebe- or more colds yearly, or scarred or perfo- tween children of middle class and working rated eardrum). Further, lower respiratory class families. This associationwas found tract illness (measured by history of fre- at each of the examinationages, including quent chest colds or episodes of bronchitis age 15. At age 15, persistence of rales and or pneumonia) was similarly associated. rhonchi (chest noise), possibly theprodrome Functional changes, in the form of reduced of adult chronic respiratory disease,was FEV0.75 ratios emerged where therewas a some tenfold less in the very low pollution past history of pneumoniaor bronchitis, of area, and a factor of two less in the low pol- persistent or frequent cough,or of colds lution area than thatin the high pollution going to the chest. Thereappears, there- area. If the 1962-1963 measuredconcentra- fore, to be a persistence of respiratorydys- tions for smoke and SOcan truly be extrap- function, even in the absence ofhigh-pollu- olated to the 15-year respiratoryillness sur- tion extant at the time of thefunction vey, then these British school children testing. The lowest "effect" level forsmoke ex- and SO: is not clearly indicated perienced increased frequencyand severity by this study, but the increased associationof "res- of lower respiratory diseasesin association with annual mean smoke piratory infections" in school childrencan concentrations be detected for areas whosemean daily figures exceed about 100 ag/m3 for smoke and piratory disease and residence in a pc fluted 120 µg /ma (0.042 ppm ) for SO:. community. The exacerbation of acute respiratory illness of school children in Ferrara, Italy, has 4.Studies of Pulmonary Function been studied by Paccagnellaet al."Air pol- Hollandet al."report decreased perform- lution measurements from 1959 through ance of the FEV1.0 test in London and Brit. 1964 permitted definition of high, medium, ish rural outside telephone workers com- and low zones of pollution. School children pared with their American counterparts. in the age range 7 to 12 had daily examina- For both groups the FEV was further de- tions, and the date of onset of acute respira- creased in relation to smoking intensity. tory disease was recorded. Although climatic FEV differences within the United Kingdom conditions were related to changes in pollut- workers (i.e., London versus rural) could ant levels, the onset of acute respiratory dis- also be related to the sulfur dioxide concen- ease in the children wasnotcorrelated sig- trations accompanying the particulate lev- nificantly with changing air pollution values, els. A more detailed discussion of the study except in the poorest socioeconomic area. appears in Section C-4. The pollutant values for this community are, Toyama 42 reported measurements of peak however, lower than those encountered in flow rate and total vital capacity perform- the British studies previously discussed (20 ance in Japanese school children in areas of µg /m, to 45 µg /m3 annual mean). In fact, differing air pollution, measured monthly; these are levels which are lower than many fluctuations were observed in the mean peak rural values in the United States. flow rates of children attending schools and Toyama 42 studied two groups of school living in 'polluted industrial areas; and the children, 10 to 11 years old, in Kawasaki, variations were smaller for children in Japan. Sulfation rates at the school in the clearer areas. Total vital capacity was not more polluted area varied from 0.5 to 1.9 significantly differentbetween pupils of the and averaged 0.9 mg/100cm2-day Pb02; no various schools.There was a substantial sulfation rates were given for the school in difference in peak flow rates between the the area of lower pollution.Dustfall was two school districts at times of highest pol- considerably less in the area of lower pollution. When pollution "values were lowest, lution (ranging from about 5 tons/km=- the differences were less. The lowest values mo. to 15 tons/km2 -mo.) * than in the more relatedtodustfall measurements of .60 polluted area (ranging from about 15 tons/ tons/km2-mo.* and daily sulfur dioxide levels km2-mo. to 70 tons/1=2-mo.). The children equivalent to 20 4/cm2 (lead candle meas- from the more polluted area had a higher urement). r frequency of nonproductive cough, irritation In Osaka, Watanabe 20 studied the peak of the upper respiratory tract, and increased flow rate and vital capacity performances by mucus secretion. Whether the effect was due the children of schools enduring differing air to oxides of sulfur or particulate matter can- pollutant concentrations. It was noted that not be determined from this study. individual peak flow rates were more mark- A study by Manzhenko 58 of upper respira- edly decreased in the winter months (Sep- tory tract conditions in school children in .tember to December, 1963) for the school Irkutsk is difficult to relate to the Sheffield in the highly polluted area than for the study. However, the higher incidence of res- school in the low pollution area. Daily mean piratory tract conditions and the undefined concentrations of both dustfall and sulfur abnormal X-ray findings in these children'r dioxide concentrations were twice as great lungs are disturbing evidence of the poss. in the polluted area as in the unpolluted area. bility of an association between serious res- In a comparison by Prindleeta" of pul-

*Ia the United States, dustfall is measured in *In the United States, dustfall is measured in tons/mi'-mo. tons/mikmo. 4} 175 167 monary function and other parameters in out apparent classification of either smoking two Pennsylvania communities with widely patterns or possible occupational or residen- different air pollution levels, average airway tial exposure differences. Increased sputum resistance and specific airway resistance production, deterioration of pulmonary func- were measured in persons 30 years of agetion performance (FEV1.0), and themore and older.These measurements were per- frequent occurrence of respiratorysymp- formed at several stations in each of thecom- toms classified as "upper" (coryza, influenza, munities and indicated differences between and acute respiratory disease), and "lower" the high-pollution and low-pollutioncommu- (chest colds,bronchitis, wheezy attacks,, nities which were probably related to the pneumonia) were all associated with in sixfold greater dustfall. However, smoking creases in both smoke and sulfur dioxide and occupation were not accounted for. concentrations. There was frequently diffi- In the paper by Lunn et al.," Sheffield culty in defining an exacerbation of disease school children were shown to have reduced inthose individuals already experiencing FEV0.75 and FVC ratios in the area of high- chronic bronchitis. During this period, ill- est pollution. The measurements were made ness peaks (attack rate) may haveoccurred: during the summer, when pollution levels with weekly mean concentrations of smoke were low and apparent incidence of acute exceeding 400 µg /m' and of sulfur dioxide respiratory infection was diminished,sug- exceeding 460 µg /m' (0.16 ppm) ;weekly gesting, in contrast to the Japanese studies mean concentrations were calculated using referred to above, that there may - beper- the highest daily mean occurring each week sistence of the respiratory function deterio- at each of 13 locations in the area: ration in relation to residence in the area of Bierstecker e3surveyed male municipal high pollution; mean dailyaverages measured at a single station were: smoke, 300 employees in Rotterdam for symptoms of µg /m'; SO2, 275 µg /m' (0.096 ppm). bronchitis and for peak flow meter perform- The studies relating morbidity and deteri- ance, and reviewed years of residence in oration in pulmonary function to particulate Rotterdam versus years of residence ina nonurban environment as wellas smoking levels cover effects which are also included habits. Level III of the World Health Organiza The individualswithbronchitis tion's "guides to air quality."23 symptoms were matched with individuals without such symptoms but with similarage 5, Studies of Panels of Bronchitis Patients and background. Sigiificant differencesre- Lowther e°relatedseveral episodes of lated to heavy cigarette smoking, butno acute urban pollution to worsening ofcon- reliable statistical indication ofan effect of dition in a group of bronchitic patients, well urban or nonurban residence in the produc- studied in a registry at St. Bartholomew's tion of symptoths was detectable. Sincepar- hospital. Changes in their symptomatolagy ticulate levels in Rotterdamare very low, the were recorded in a daily diary and acute range of difference between particulate levels worsening in significant numbers of the in Rotterdam' aifd the nonurban environment group was associated with daily rises in air may have been close to minimal. pollution above 300 µg /m' of smoke and 600 Fletcher et al." followed 1,136 working pg/m3 (021 ppm) of sulfur dioxide: Figure men aged 30 to 59. in West London' by sur- 11-8 shows graphically the effects observed veys at 6-month interval& The surveys in- on 29 bronchitic patients of high pollution cluded collection and measurement ofmorn- levels in January 1954 ing sputum volume, FEV, and respiratory Angel et at." reviewed theoccurrence of symptom j questionnaires.While expected new reepiratory symptoms in; men, Working patterns of decline in lung function withage in factories and in offices, most of Whom occurred and thiswas the most rapid in had prior evidence of chronic bronchitis. cigarette smokers with low lung fuction to The study, group of 85men obserYed through start with, an unexpected findingwas a de-. +ha + L W ttf aao_i no .1 - 18 17 18 19 20 21 22

100 90 RH 50 60 PERCENT MEAN 45 80 TEMP oF 40 70 35

2.0

1.8 1.6

SMOKE 1.4 mg / m3 1.2 1.0 0.8 0.6 0.6 0.5

0.4 0.4 SO2 0.3 PPm NUMBER OF 0.2 PATIENTS 4 0.1 WORSE 0 4 BETTER 8

JANUARY 1954 FIGURE 11-8. Effect on Bronchitic Patients of High Pollution Levels (January 1954)." (The figure represents the effect on bronchitic patients of increased pollution levels; patients stated whether they regarded their condition as "worse" or better".) sistent in the winter samples, but shOwed a that of the decrease in smoke.Possible significant trend in samples taken together changes in cigarette tars, in methods.of as well as in the winter samples. (Trend smoking and in techniques for collecting a data are based on 825 men whO attended sample, or other factors, could have influ- at least nine periodic examinations.)The enced this result. authors felt this was possibly due to a de- 1st hour sputum volumeIn men of cline in air pollution in London. They pre- constant smoking habits sented data on trends in SO, and black suspended matter which indicated that there is 1961.19651968 196419651966 a consistent downward trend in particulate Summer 1.650.830.93:0.930.830.72 pollution(highly significant)but a less Winter 1.381.271.20 1.180.70 D. SUMMARY steady decline in 502.'. This unique set of data could mean that This chapter reviews epidemiologic studies with a decrease of smoke 'pollution (yearly of the relationship between pollutant con- mean) from 140 pgim3 to 60 isg/ins, there is centrations and their effects on health. In- indicators were under review, and in these Lawther, in reviewing a long series of ob- cases it is possible to state pollutant levels servations on the condition of bronchitic at which an effect is noted. However, such patients, estimated that they tended to be- values cannot be taken to mean that effects come worse when daily levels of smoke ex- will not be noted at lower concentrations. ceeded 300 µg /m' with SO2 over 600 pg/ms. Most studiesinvolving long-termeffects Angel et al. made somewhat similar obser- using a geographic area comparison willuse vations with smoke above 400 µg /m' and the cleanest area as the "control"area SO: over 460 µg /m'. against which mortality and morbidity dif-' Winkelstein found in Buffalo that in- ferentials are to be found. This necessarily creases in the mortality rate were signifi- assumes that this "cleanest" area itself does cantly linked to higher levels of suspended not have any effects from its level of pollu- particulate pollution.His studies showed tion.Conversely, some studies have com- that mortality from all causes, from chronic pared areas with very low particulate load- respiratory diseases, and from gastriccar- ing or with very limited ranges of differ- cinoma increased from the lowest of his ences. It is not possible to dethonstrate any five levels of pollution (less than 80 µg /m') relationship under conditions of minimum through the three higher ranges, after the values, or minimal differences.. Table 11-6 effects of socioeconomic status had beencon- summarizes the epidemiologic studiesre- sidered.Zeidberg found in Nashville sig- viewed according to the several indices. nificant increases in all respiratory deaths From the material reviewed in this chap- at soiling levels over 1.1 cohs annual aver- ter, a selection has been made of data from age. Neither of these studies took smoking those studies which furnish the best quan- habits into account, and the Nashville study titative information that we have available only. partiallyallowed for socioeconomic at the present time. Levels are given in the factors. measurement system used in the original .Studies of illness in relation to residence observations,since conversion from one in more- and less-polluted areas contribute method to 'another is not recommended. At- additional information. Fletcher et al. noted tention should be given to the difference be- a proportional decline in the production of tween British "smoke" and American "sus- morning sputum in chronic bronchitics in pended particulate" measurements. Bothare West London from 1961 to 1966 as smoke given in micrograms per cubic meter of air, pollution in their residence areas declined but they are not identical. Limited data in- from 140 µg /m' annual mean. Douglas and dicate that the American valuesmay be Waller found an increase in frequency and higher in the same situation.In making severity of lower respiratory illness at smoke use of these data,- attention must also be ;and SO: levels over 130 µg /m® annualaver- given to the averaging' time whichwas em- age. The Sheffield study by Lunnet al.' ployed 'in the original observation. Long- shows similar differences occurring. with term averages are, of necessity, considekably some morbidity measures between about lower than selected high daily means in the 100 pg/ins and 200 pg/ms of smoke, and for same locations. others between 200 µg /m' and 300µg /m' British studies of acute episodes of in- annual average. creased pollution show excess deathsoccur- A study of British workmen found in- ring at smoke levels from 750 1.4g/m3 to 2,000 creased respiratory illness absence inareas pg/ms. High 802 levels are, ofcourse, con- w_ ith smoke levels inexcess of 200 lg. g/m3.. currently present :The excesses of mortal- Physiologic studies of lung function have ity are. always accompanied bya very large also been made in- both adults and children. increase in Illness, -2nninly exacerbations of On the basis of present limited knowledge chrOnic eonditions; Similar:: but lessspec- it appears that the alterations foundmay be tacular ATIktlILISt in'Mgtv vnni, rs'

Table 11-6 (continued).SUMMARY TABLE OF EPIDEMIOLOGICAL STUDIES .., . g .5 4 1 lid Oki rs E 2811.1. 32 *a TA el) 2 C! = as Aget El 1.04 4:1 .q' tiroIV a § VIE 8 1 co as co, &E & 0:1 cnNI i ... Health hides I . 0 Findings cn 1 O A

8. Japan Peak flow rates decreased more in 20 winter for children in polluted areas than in less polluted areas. 4. Pennsylvania, Possible relation of dustfall and 69 2 com- SO: differences in average and munities. specific airway resistance of subjects in the two communities. 6.Sheffield, U.K. 100 275 Reduced FEVom and FVC in 66 areas of highest pollution. Possible persistence of respiratory function deterioration related to residence in area of high pollution. I.Studies of panels of bronchitic patients: 1. London, 300 >600 Acute worsening of symptoms in 60 November, bronchitis patients. 1965-May, 1966.1 2. U.K., October, 400 460 : Possible increase in respiratory 62 1962-April, disease attack rates. 1963. 3. Rotterdam, n.a. n.a. No indication of residence effect 68 'Netherlands. on bronchitis symptoms. 4. London 140 pg/m3 200 pg/m3 Decrease in morning sputum 64 declining declining volume with decreasing air to to pollution levels in bronchitis 60 penis. 160 pgim3. patients under observation during 6 years. study shows reduced pulmonary function in severity. This association is most firm for the children in the most polluted area, i.e., the short-term air pollution episodes. where smoke concentration is above 300. There are probably no communities which pg/m2.Studies in Japan show a decrease do not contain a reservoir of individuals with in pulmonary function in school children liv- impaired health who are prime targets for ing in areas of high dustfall as compared the effects of elevated levels of particulate with those living in low duatfall areas.. In matter and sulfur oxides. However, to show Osaka the dustfall levels were 6.5 gm/m2- small changes in deaths associated with co- month and 13.3 gm/m2-month. incident higher levels of air pollutants re- The analyses of the numerous epidemio- quires extremely large populations. In small logical studies discussed clearly indicate an cities, these small changes cannot be de- association between air tiollution.1, as aim- tected ti

in Relation to Air Pollution." Arch. Environ. 59. Prindle, R. A., 'Wright, G. W., Health. 18:636-643, 1969. McCaldin, R. 0., 53. Reid, D. D. "Air Pollution and Marcus, S. C., Lloyd, T. C., andBye, W. E. Respiratory Dis- "Comparison of Pulmonary Functionand Other ease in Children." In: Bronchitis, SecondIn- Parameters in Two Communities ternational symposium, Groningen,The Nether- with Widely lands, April 22-24, 1964. Different Air Pollution Levels." Am.J. Public Health 53:200-218, 1963. 54. Douglas, J. W. B. and Waller,R. E. "Air Pol- 60. Lawther, P. J. "Climate, lution and Respiratory Infectionin Children." Air Pollution, and Chronic Bronchitis." Proc. Roy.Soc. Med. 51: Brit. J. Prevent. Soc. Med. 20:1-8,1966. 262-264, 1958. 55. Holland, W. W. and Elliott, A."Cigarette Smok- 61. Waller, R. E. and Lawther, P. J. ing, Respiratory Symptoms,and Antismoking "Some Obser- vations on London Fog." Brit. Med..).4952:1356- Propaganda : an Experiment." Lancet1:41-43, 1968. 1358, Dec. 3, 1955. 56. Lunn, J. 62. Angel, J. H.Fletcher, C. M.,Hill, I. D., and E., Knowelden, J., and Handyside, Tinker, C. M. "Respiratory Illness in A. J. "Patterns of Respiratory Illnessin Shef- Factory and Office Workers." Brit. J. DiseasesChest field Infant School Children." Brit.- J.Prevent. 59:66-79, 1965. Soc. Med. 21:7-16, 1967. 63. Biersteker, K. "Air Pollution 57. Paccagnella, B., Paranello, R., andPesarin, F. and Smoking as Cause of Bronchitis among 1,000 MaleMunici- "The Immediate Effects of Air Pollutionon the pal Employees in Rotterdam (The Health of School Children in SomeDistricts of Netherlands). Arch. Environ. Health.'18:531-536,1969. Ferara." Arch. Environ. Health. 18:495,502, 1969. 64. Fletcher, C. M., Tinker, B. M.,Hill, I. D., and Speizer, F. E. "A Five-Year ProspectiveField 58. Manzhenko, E. G. "The Effect ofAtmospheric Study of Chronic Bronchitis." Pollution on the Health of Children." Preprint (Pre- Hyg. Sara. sented at the 11th Aspen Conferenceon Re- 31:126-128, 1966. search in Emphysema June 1968.) the settleable portion of particulate air pollu- (NASN), which uses the high-volume samp- tion. Typical values for cities are 10 to 100 ler. NASN currently operates some 200 tons/mile2-month; as high as 2,000 tons/ urban and 300 non urban stations, and is mile2-month have been measured in the vicin- supplemented by State and local networks. ity of especially offensive sources. Levels of From the NASN data, the annual geometric dustfall have apparently declined in some mean concentrations of suspended particu- American cities, and dustfall measurements late matter in urban areas range from 60 are probably not useful as an index of over- Ag/m3 to about 200 Ag/m3. The maximum 24- all particulate air pollution. However, dust- hour average concentration is about three fall itself constitutes a nuisance, and its times the annual mean, but values of seven measurement can be used as an index of the times the annual mean do occur. Mean par- dirtiness of air pollution. ticulate concentrations correlate, in general, Several methods are available for measur- with urban population class, but the range ing suspendedparticulateconcentrations. of concentrations for any class is broad, and The most commonly used device is the high- many smaller communities have higher con- volume sampler, which consists essentially centrations than larger ones. For nonurban of a blower and a filter, and which is usually areas the annual geometric mean is typically operated in a standard shelter to collect a between 10 µg /m3 and 60 µg /me. 24-hour sample. The sample is weighed to determine concentration, and is usually ana- ...A.Effects on Health lyzed chemically. The hi-vol is considered a Fort ft most part, the effects of particu- reliable instrument for measuring the weight late air pollution on health are related to of total particulate matter. Chemicel analysis injury to the surfaces of the respiratory sys- of the hi-vol sample, however, may be limit- tem. Such injury may be permanent or tem- ed: the filter material may contaminate the porary. It may be confined to the surface, or sample; different substances in the sample it may extend beyond, sometimes producing may react with each other; and losses may functional or other alterations. Particulate occur throughvolatilizationof material. material in the respiratory tract may pro- Tape *mplers, which collect suspended par- duce injury itself, or it may act in conjunc- ticulate matter on filters and analyze the tion with gases, altering their sites or their sample optically, are also in common use. modes of action. While these samplers are inexpensive and Laboratory studies of man and other ani- rugged, they yield data which cannot always mals show clearly that the deposition, clear- be easily interpreted in terms of particulate ance, and retention of inhaled particles is a mass concentration. Other techniques avail, very complex process, which is only begin- able for measuring particulate pollution in- ning to be understood. Particles cleared from clude optical systems, which provide an indi- the respiratory tract by transfer to the cation of concentration without requiring lymph, blood, or gastrointestinal tract may that a sample be taken. exert effects elsewhere. Few studies have in- The averaging time used for measuring vestigated the possibility of eye injury by suspended particulates is not as significant a particles in the air; only transient eye irrita- factor as it is for gaseous pollutants. The tion from large dust particles presently is basic unit of time is 24 hours.' Values taken known to be a problem. over this period may be combined into week- Theavailabledatafromlaboratory ly, monthly, seasonal, and annual means as experiments do not provide suitable quantita- required. The relationships between daily tive relationships for establishing air quality and other longer time periods in the United criteria for particulates. The constancy of States is known with some degree of precis- population exposure, the constancy of tem- ion, as data exist for a 10-year period. perature and humidity, the use of young, Most of the data on mass concentrations normal, healthy animals, and the primary of suspended particulates come from the focus on short-term exposures in many lab- NationalAirSurveillanceNetworks, oratory studies make extrapolation from 182 190 ; . these studies of limited value for the general in illness have been observed in London at population, and singularly risky for special smoke levels above 750 pg/ms and in New risk groups within the population. These York at a smokeshade index of 5-6 cohs. Sul- studies do, however, provide valuable inform- fur oxides pollution levels were also high in ation on some of the bioenvironmental rela- both cases. These unusual short-term,mas- tionships that may be involved in the effects sive exposures result in immediatelyappar- of particulate air pollution on health. The ent pathologic effects, and they represent the data they provide on synergistic effects 'show upper limits of the observed dose-response very clearly that information derived from relationship between particulates and ad- single-substance exposures should be applied verse effects on health. - to ambient air situations only with great Daily averages of smoke above 300pg /ma caution. to 400 pg/m3 have been associated with acute Epidemiological studies do not have the worsening of chronic bronchitis patients in precision of laboratory studies, but they have England. No comparable data are available the advantage of being carried out under in this country. Studies of British workmen ambient air conditions. In most epidemiologi- found that increased absences due to illness cal studies, indices of air pollution levelare occurred when smoke levels exceeded 200. obtained by measuring selected pollutants, µg/ms most commonly particulates and sulfurcom- Two recent British studies showed in- pounds. To use these same studies to estab- creases in selected respiratory illnessin lish criteria for individual pollutants is justi- children to be associated with annualmean fied by the experimental data on interaction smoke levels above 120 pg/ms. Additional of pollutants. However, in reviewing there- health changes were associated with higher sultsofepidemiologicalinvestigations it levels. These effects may be of substantial should always be remembered that the speci- significance in the natural history of chronic fic pollutant under discussion is being used bronchitis. Changes beginningin young as an index of pollution, not as a physico- children may culminate in bronchitis several chemical entity. decades later. In epidemiologcial studies consistency of The lowest particulate levels at which results at different times and places is im- health effects appear to have occurred in this portant in determining the significance of country are reported in studies of Buffalo observations. However, while polluted air has and Nashville. The Buffalo study clearly many similarities from place to place and shows increased death rates from selected from time to time, it is not identical in all causes in males and females 50 to 69 years communities or at all times, and complete old at annual geometric means of 100 pg/ma consistency between epidemiological studies and over. The study suggests that increased should not be expected. Thereare not a large mortality may have been associated with number of suitable epidemiological studies residence in areas with 2-year geometric available at present, but those thatare avail- means of 80 µg /ms to 100 pg/ms. The Nash- able show some consistency in the levels at ville study suggests increased death rates which effects were observed tooccur. for selected causes at levels above 1.1 cohs. Considerable data have been presentedon Sulfur oxides pollution was also present dur- a number of air pollution episodes in London ing the periods studied. In neither study and in New York City. In reviewing thesewere the smoking habits of the decedents data it should, be remembered that British known. air pollution measurementsare not entirely Corroborating informationissupplied comparable with American measurements. from Fletcher's study of West London work- The only published comparison indicates that ers between the ages of 30 and 59. The data the British method of measuring particulates indicate that with a decrease of smoke pollu- tends to give somewhat lower readings than tion (yearly mean) from 140 pg /ma to 60 American methods. pg/me, there was an associated decrease in Excess deaths and a considerable increasemean sputum volume. Fletcher noted that

183 191 there may have been changes in the tar com- about by increased concentrations of particu- position of cigarettes during the period stud- late air pollution, may be more than cancel- ied; such a change could affect the findings. ling out the climatic effect of the increased This study provides one of the rare oppor- carbon dioxide. That worldwide particulate tunities to examine the apparent improve- air pollution has been increasing is evidenced ment in health that followed an improvement by the fact that in the United States and in in the quality of the air. other countries, turbidity, a phenomenon produced by the. back-scattering of direct 3.Effects on Climate Near the Ground sunlight by particles in the air, has increased Particles suspended in the air scatter and significantly over the last several decades. absorb sunlight, reducing the amount of solar 4.Effects on Visibility energy reaching the earth, producing hazes, and reducing visibility. Suspended particu- Particles suspended in the air reduce vis- late matter plays a significant role in bring- ibility, or visual range, by scattering and ing about precipitation, and there is some absorbing light coming from both an object evidence that rainfall in cities has increased and its background, thereby reducing the as the cities have developed industrially. contrast between them. Moreover, suspended particles scatter light into the line of sight, Suspended particulate matter, in the con- illuminating the air between, to further de- centrations routinely found in urban areas, grade the contrast between an object and its considerably reduces the transmission of background. solar radiation to the ground, creating an The scattering of light into and out of the increased demand for artificial light. The line of viewing by particles in the narrow effect is more pronounced in the winter than range of 0.1 14 to 1 14 in radius has the greatest in the summer, when particulate pollution effect on visibility. Certain characteristics of loadings are higher, and sunlight must pene- behavior of these particles make it possible trate more air to reach the ground. For to formulate a useful approximate relation- similar reasons the effect is also more pro- ship between visual range and concentrations nounced during the workweek than on week- of particulate matter: ends, during industrial booms, and in higher latitudes. For a typical urban area in the ,- AX 103 United States, with a geometric mean annual G' particulate concentration of roughly 100 where G'. particle concentration (µg /me), ag/m3, the total sunlight, including that re- L,= equivalent visual range, and ceived directly from the sun and that reflect- .4 A=1.22for L, expressed in kilome- ed by the sky, is reduced five percent for 0.6 every doubling of particle concentration. The 1.5 reduction is most pronounced on ultraviolet tent and 0.750.38 radiation. For urban areas in the middle and high for L, expressed in miles latitudes, particulate air pollution may re- The value 1.2 for A is the mid-range value duce direct sunlight by as much as one-third empirically obtained from observations in a in the summer and as much as two-thirds in variety of air pollution situations. The data the winter. This effect may have implica- indicate that the range 0.6 to 2.4 covers tions for tha delicate heat balance of the virtually all cases studied. The relationship earth's atmospheric system. In spite of an does not hold at relative humidities above 70 increase in the carbon dioxide content of the percent, nor does it apply to fresh plumes atmosphere over the past several decades, from stacks, and it may not hold for the which would presumably bring about an products of photochemical reactions. A com- increase in atmospheric temperature, mean panion document, Air. Quality Criteria For worldwide temperatures have been decrease Sulfur Oxides, discusses a relationship being since the 1940's. Increased reflection of tween levels of sulfur dioxide and visual solar radiation back to outer space; brought range at various relative humidities. 184 492- ' Within the limitations prescribed, the re- at relative humidities above 70 percent; and lationship provides a useful means of esti- they greatly increased when traces of sulfur mating approximate visual range from par- dioxide were added to the laboratory air. ticulate concentrations. In addition to aesthe- It is apparent that the acceleratedcorro- tic degradation of the environment, reduced sion rates of variomanetals in urban and visibility has serious implications for safe industrial atmospheres are largely the re- operation of aircraft and motor vehicles. At sult of relatively higher levels of particulate a visual range of less than 5 miles, opera- Pollution and sulfur oxides pollution. High tions are slowed at airports because of the humidity and temperature also play an im- need to maintain larger distances between portant synergistic part in this corrosion re- aircraft. Federal Aviation Administration action.Studies show increased corrosion restrictions on aircraft operations become rates in industrial areas where air pollution increasingly severe as the visual range de- levels, including sulfur oxides and particu- creases below 5 miles. Using the upper and lates, are higher. Further, corrosion rates lower bounds of the relationship described are higher during the fall and winter sea- above, visibility could be 5 miles at a par- sons when particulate and sulfur oxides pol- ticulate loading as high as 300 µg /m3 or as lution is more severe, due to a greater con- low as 75 µg /m3. However, on the average, sumption of fuel for heating. visibility can be expected to be reduced to Steel samples corroded 3.1 times faster in approximately 5 miles at a particulate con- the spring of the year in New York City, centration of 150 µg /m3. At a level of 100 whereannualparticulate *concentrations ',terns, visibility is reduced to 71/a miles. This average 176 µg /m3, than did similar samples limited distance, however, may be related to in State College, Pennsylvania, where the particulate concentrations as low as 50 fig/m3 average concentrations were estimated to and as high as 200 µg /m3. range from 60 pg/m3 to 65 µg /m3. In the fall of the year, when particulate and sulfur 5.Effects on Materials oxide concentrations in New York were considerably higher than in the spring, the steel Particulate air pollution causes a wide samples in New York corroded six times range of damage to materials. Particulate faster than the samples at State College. matter may chemicallyattackmaterials Similar findings were reported for zinc through its own instrinsic corrosivity, or samples. Moisture may have contributed to through the corrosivity of substances absorb- the corrosion. ed or adsorbed on it. Merely by soiling ma- In Chicago and St. Louis, steel panels were terials, and thereby causing their more fre- exposed at a number' of sites, and measure- quent cleaning, particulates can accelerate ments taken of corrosion rates and of levels deterioration. of sulfur dioxide and particulates. In St. Laboratory and field studies underscore Louis, except for one exceptionally polluted the importance of the combination of par- site, corrosion losses correlated well with sul- ticulate matter and corrosive gases in the fur dioxide levels, averaging 30 percent to deterioration of materials. On the basis of 80 percent higher than losses measured in present knowledge, it is difficult to evaluate nonurban locations. Sulfation rates in St. precisely the relative contribution of each of Louis, measured by lead peroxide candle, also the two classes of pollution; however, some correlated well with weight loss due to general conclusions may be drawn. corrosion. Measurements of dustfall in St. Particulates play a role in the corrosion of Louis, however, did not correlate significant- metals. In laboratory studies,steel test ly with corrosion rates. Over a 12-month panels that were dusted with a number of period in Chicago, the corrosion rate at the active hygroscopic particles commonly found most corrosive site (mean SO2 level of 0.12 in the atmosphere corroded even in clean ppm) was about 50 percent higher than at air. Corrosion rates were low below a rela- the least corrosive site (mean SO2 level of tive humidity of 70 percent; they increased 0.03 ppm). Although suspended particulate

185 levels measured in Chicago with high-volume 6.Economic Effects of Atmospheric samplers also correlated with corrosion rates, Particulate Matter a covariance analysis indicated that sulfur dioxide concentrations were the dominant It is not possible at the present stage of influence on corrosion. Based on these data, knowledge to provide accurate measures of it appears that considerable corrosion may all the costs imposed on society by particu- take place (i.e., from 11 percent to 17 per- late air pollution. Selected categories of cent weight loss in steel panels) at annual effects can be quantified; it is obvious that average sulfur dioxide concentrations in the these estimates represent a significant under- range of 0.03 ppm to 0.12 ppm, and although statement of the total cost. high particulate levels tend to accompany 7.Effects on Vegetation high sulfur dioxide levels, the sulfur dioxide concentration appears to have the more Relatively little research- has been carried important influence. out on the effects of particulate air pollution Particulate air pollution damages electri- on vegetation, and much of the work that cal equipment of all kinds. Oily or tarry par- has been performed has dealt with specific ticles, commonly found in urban and indus- dusts, rather than the conglomerate mixture trial areas, contribute to the corrosion and normally encountered in the atmosphere. failure of electrical contacts and connectors. This document reports briefly on some of Dusts can interfere with contact closure, and these specific particulate studies only to illus- can abrade contact surfaces. Hygroscopic trate the possible mechanisms through which dusts will absorb water and forin thin elec- particulate matter may affect vegetation. trolytic films which are corrosive. This information is not presented for the purpose of establishing air quality standards Particulatessoil and damage buildings, on these specific pollutants. statuary, and other surfaces. The effects are Thereisconsiderableevidencethat especially severe in urban areas where large cement-kiln dusts can damage plants. A quantities of coal and sulfur-bearing fuel marked reduction in the growth of poplar oils are burned. Partii;les may act asreser- trees 1 mile from a cement plant was observ- voirs of acids, and thereby sustain a chemical ed after cement production was more than attack that will deteriorate even the more doubled. Plugging of stomates by the dust resistant kinds of masonary. Particles stick may have prevented the exchange of gases to surfaces, forming a film of tarry soot and in leaf tissue that is necessary for growth grit which oftentimes is not washed away by and development. Moderate damage to bean rain. Considerable money and effort have plants occurred when the plant leaves were been spent in many cities to sandblast the dusted at the rate of 0.47 mg /cm= -day (400 sooty layers that accumulate on buildings. tons /m=- month) for 2 days and then exposed Water-soluble salts, commonly found in ur- to natural dew. The mechanism through ban atmospheres, can blister paint. Other which the leaves are damaged is not en- particles may settle on newly paintedsur- tirely understood, but direct alkaline dam- faces, causing imperfections, thereby in- age to tissues beneath the crust formed by creasing the frequency with which a surface the dust and moisture has been observed. The must be painted. deposits may also plug stomates and block The soiling of textiles by the deposition of light needed for photosynthesis. Cement- dust and soot on fabric fibers not only makes kiln dusts may change the alkalinity of soils them unattractive, and thereby diminishes to benefit or harm vegetation, depending on their use, but results in abrasive wear of the the species. fabric when it is cleaned. Vegetable fibers, Dust deposits may also eliminate preda- such as cotton and linen, and syntheti' nylons tors, and thereby bring on increased insect are particularly susceptible to chemical at- injury to plants; they may interefere with tack byacidcomponentsofairborne pollen germination; and they may make particles. plants more susceptible to pathogens. 186 ,1194 Fluoride dusts apparently have a difficult It is thought that the reaction to suspended time penetrating leaf tissue in physiologi- particulates as a nuisance probably occurs cally active form, and they are much less dam- at peak concentrations, and not necessarily aging to vegetation than isgaseous fluoride. at the values representing annual means. Soluble fluoride dusts may be absorbed by However, the relationship provides a useful the plant, but the amount is relatively small example of how the nuisance effect of air compared to that which can enter the plant pollution relates to concentrations. Approxi- in gaseous form. The evidence suggests that mately 10 percent of the study population there is little effect on vegetation at fluoride considered air pollution a nuisance in areas particulate concentrations below 2 pg/m3. with suspended particulates at an annual Concentrations of this magnitude and above geometric mean concentration of 80 µg /m3. can sometimes be found in the immediate At this same level of pollution, 30 percent of vicinity of sources of fluoride particulate the study' population was "aware of" air pollution; they are rarely found in urban pollution. In areas with 120 1&g/m3 (annual atmospheres. geometric mean), 20 percent were "bothered Ingestion of particles deposited on plants by" and 50 percent were "aware of" air pol- can be harmful to animal health. Fluorosis lution; in areas with an annual geometric and arsenic poisoning have been brought on mean of 16f, µg /m3, one-third of the popula- through this medium. tion interviewed were "bothered by" and Soot may clog stomates and may produce three-fourths were "aware of" air pollution. necrotic spotting if it carries with it a soluble Although data from other studies do not toxicant, such as one with excess acidity. readily lend themselves to quantitative for- Magnesium oxidedeposits on soils have been mulation, they do, in general, support the shown to reduce plant growth, while iron relationship reported by the St. Louis study. oxide deposits on soils have been shown to A study of communities in the Nashville, reduce plant growth, while iron oxide de- Tennessee, metropolitan area in 1957 found posits appear to have no harmful effects, and that at least 10 percent of the population ex- may be beneficial. pressed concern about the nuisance of stir pollution at dustfall levels exceeding 10 tons/ 8.Effects on Public Concern mil- month. Several studies indicate that there is a relationship between levels of particulate 9.Suspended Particles as a Sources pollution, used as an index of air pollution, of Odor and levels of public concern over the problem. A study conducted in 1963 in the St. Particulate air pollution is not ordinarily Louis metropolitan region found a direct considered a significant source of odors. linear relationship between the fraction of However, there is evidence that liquid and a community's population who said air pollu- even solid particles of some substances may tion was a nuisance, and the annual mean be volatile enough to vaporize in the nasal concentration of particulate air pollution in cavity, and produce sufficient gaseous ma- the community. The relationship, which was terial to stimulate the sense of smell. Fur- derived from data on communities in the St. ther, particles may carry absorbed odorants Louis area whose annual concentrations into the nasal cavity, and there transfer them ranged from 50 µg /m3 to 200 µg /m3, was to olfactory. receptors. A survey of State and formulated as: local air pollution control officials revealed that approximately one-fourth of the most frequently reported odors are those which y=0.3x 14 are known to be, or are suspected to be, asso- where y= population fraction (%) ciated with particulate air pollution. The concerned, and sources of these odorous particles are div- x=annual geometric mean par- erse, including diesel and gasoline engine tide concentration (pg/m2). exhausts, coffee-roasting operations, paint spraying, street paving, and the burning of munity exposures to particulate matter and trash. respiratory disease incidence and prevalence B.CONCLUSIONS rates is conservatively believed to be intermediate in its reliability. Because of the re- The conclusions which follow are derived enforcing nature of the studies conducted to from a careful evaluation by the National date, the conclusions to be drawn from this Air Pollution Control Administration of the type of study can be characterized as prob- foreign and American studies cited in previous chapters of this document. They repre- able. sent the Administration's best judgment of The association between long-term resi- the effects that may occur when various dence in a polluted area and chronic disease levels of pollution are reached in the atmos- morbidity and mortality is somewhat more phere. The data from which Lie conclusions conjectural. However, in the absence of other were derived, and the qualifications which explanations, the findings of increased mor- should be considered in using the data,are bidity and of increased death rates for select- identified by chapter reference in each case. ed causes, independent of economic status must still be considered consequential. 1.Effects on Health Based on the above guidelines the following conclusions are listed in order.of reliabil- Analyses ofnumerousepidemiological studies clearly indicate an association be- ity, with the more reliable conclusiiis first. tween air pollution, as measured by particu- Refer to Chapter 11 for cautions to be taken late matter accompanied by sulfur dioxide, in comparing British and American air qual- and health effects of varying severity. This ity measurement data. association is most firm for the short-term a. AT CONCENTRATIONS OF 750 air pollution episodes. µg /m' and higher for particulates on a 24- There are probably no communities which hour average, accompanied by sulfur dioxide do not contain individuals with impaired concentrations of 715 µg /m3 and higher, health who are particularly susceptible to excess deaths and a considerable increase in the adverse effects of elevated levels of par- illness may occur. (British data; see Chapter ticulate matter and sulfur oxides. However, 11, Section C-1) to show small changes in deaths associated b. A DECREASE FROM 140 µg /ms to 60 with coincident higher levels of air pollutants WM' (annual mean) in particulateconcen- requires extremely large populations. In trations may be accompanied by a decrease small cities, these changes are difficult to in mean sputum volume in industrial work- detect statistically. ers. (British data; see Chapter 11, Section The epidemiologic studies concerned with C-4) increased mortality also show increasedmor- bidity. Again, increases in morbidityas c. IF CONCENTRATIONS ABOVE 300 measured, for example, by increases in hos- µg /m' for particulates persist on a 24-hour pital admissions or emergency clinic visits, average and are accompanied by sulfur diox- are most easily demonstrated in major urban ide concentrations exceeding 630µg /me over areas. the sameaverage,period, chronic bronchitis For the large urban communities which patients will likely suffer acute worsening of are routinely exposed to relatively high levels symptoms. (British data; see Chapter 11, of pollution, sound statistical analysiscan Section C-3) show with confidence the small changes in d. AT CONCENTRATIONS OVER 200 daily mortality which are associated with tig/mi for particulates on a 24-houruverage, fluctuation in pollution concentrations. Such accompanied by concentrations of sulfur analysis has thus far been attempted only dioxide exceeding 250 µg /mmover the same in London and in New York. average period, increased absence of indus- The association between longer-termcora- trial workers due to illness mayoccur. (Brit- 188 is ish data; see Chapter 11, Section C-5) 4.Effects on Materials e. WHERE CONCENTRATIONS RANGE AT CONCENTRATIONS RANGING FROM 100 µg /m' to 130 p g / in, and above for FROM 60 p g/m3 (annual geometric mean), particulatei (annual mean) with sulfur di- to 180 item' for particulates (annual geo- oxide concentrations (annual mean) great- metric mean), in the presence of sulfur diox- er than 120 p g/m3, children residing in such ide and moisture, corrosion of steel and zinc areas are likely to experience increased inci- panels occurs at an accelerated rate. (Amer- dence of certain respiratory' diseases. ican data; see Chapter 4, Section B) f. AT CONCENTRATIONS ABOVE 100 item' for particulates(annual geometric 5.Effects on Public Concern mean) with sulfation levels above 30 mg/ AT CONCENTRATIONS OF APPROXI- cm2-mo., increased death rates for persons MATELY 70 pg/ms for particulates (annual over 50 years of age are likely. (American geometric mean), in the presence .of other data; see Chapter 11, Section C-2) pollutants, public awareness and/or concern for air pollution may become evident and in- g. WHERE CONCENTRATIONS RANGE crease proportionately up to and above con- FROM 80 Item' to 100 p Wm' for particu- centrations of 200 p g/m3 for particulates. lates (annual geometric mean) with sulfa- (See Chapter 7, Section B-1) tion levels of about 30 mg /cm= -mo., increased death rates for persons over 50 years of age C. RESUME may occur. (American data; see Chapter 11, In addition to health considerations, the Section C-2) economic and aesthetic benefits to be obtained from low ambient concentrations of par- 2.Effects on Direct Sunlight ticulate matter as related to visibility, soiling, AT CONCENTRATIONS RANGING corrosion, and other effects should be con- FROM 100 item' to 150 it Wm' for particu- sidered by organizations responsible for lates, where large smoke turbidity fac ors romulgating ambient air quality standards. persist, in middle and high latitudes direct Under the conditions prevailing in areas sunlight is reduced up to one-third in sum- where the studies were conducted, adverse mer and two-thirds in winter. (American health effects were noted when the annual data; see Chapter 2, Section C-2) geometric mean level of particulate matter exceeded 80 p g / .Visibility reduction to about 5 miles was observed at 150 p g/m3, and 3.Effects on Visibility adverse effects on materials were observed at AT CONCENTRATIONS OF, ABOUT an annual mean exceeding 60 p g/m3. It is 150 µg /m' for particulates, where the pre-: reasonable and prudent to conclude that, when dominant particle size ranges from 0.2N.to promulgating ambient air quality standards, 1.0 it and relative humidity is less than 70 consideration should be given to require- percent, visibility is reduced to as low as 5 ments for margins of safety which take into miles. (American data; see Chapter 3, Sec- account long-term effects 'on health and tion E-4) materials occurring below the above levels.

189Ne 1.97

APPENDIX ASYMBOLS

A b Brea of the filter stain, cm= abs aerosol B extinction coefficient dueto absorption turbidity coefficient ( empirical ), A = 0.5it by aerosol particles C b particle concentration in the air,µg /m3 abs gas Be turbidity coefficient, measured on the extinction coefficient dueto absorption ground by gas such as NO2 b B. Rayleigh turbidity coefficient, measured at height extinction coefficient dueto scatter by z above the ground gas molecules I b light intensity, usually in ergs/cm=fsec scat Ie initial or incident light intensity extinction coefficient due to scatter by aerosols d equivalent visual range, or visibility, but diameter of a spherical particle, cm calculated on basis of a constant scat- e tering coefficient, b, along the line of Napierian log base ( =2: .82818) sight gacceleration of gravity, cm/sec= P m probability index of refraction P (A) solar transmission factor for atmos- correlation coefficient V phere aerosols; it is a function of A settling velocity of a particle, cm/sec X particle mass concentration in the air, distance, m or cm usually in µg /m2 z S height above ground, meters scattering cross-section, cm= /particle a light scattering coefficient(empirical) Scderived surface particle concentration, relates b to A gi cm 2 /3 turbidity coefficient for A=144 T transmissivity, I/Io viscosity of air, or othergas, poises V A volume of air sampled, m3 wavelength of light Angstroms, microns, b or nanometers extinction coefficient, m-3( =b X abs aerosol probability function, usually expressed + b + b +b ) abs gas Rayleigh seat as x2 ("Chi square")

192 .1.89 1 I. APPENDIX BABBREVIATIONS

A Angstrom, 1A =10 -6 cm m3 cubic meter BTPS body temperature, pressure, mg milligram saturated mi mile cm centimeter, lcm = 10-2m mi= square mile cm= square centimeter min minute cm3 cubic centimeter ml milliliter CMD count median diameter MMD mass median diameter coh coefficient of haze mo month DMBA,10-dimethy1-1, 2 benzanthracene millimicron, 0.001p, FEV forced expiratory volume micron, 1p,= 10-4cm= 10-om = 104A FVC forced vital capacity wg microgram g mass, grams ppm parts per million hr -hour RUDS reflectance unit of dirt shade 1 liter sec second m length, meter yr year

193 200 APPENDIX C.- CONVERSIONFACTORS To convert To Multiply by mg/ms Perna 1000 mg/100 m3 µg /m3 10 µg /ft3 pg/ms 35.314 pg/1000 m3 ;terns 10-4 itg S02 /m3 ppm SO2 (vol) 3.5 x 10-' (0°C, 760 mm Hg) ppm SO2 (vol) SO2 aims (0° C, 760mm Hg) 2860 tons/mi2-mo mg/cm3-mo 3.5 x 10-2 tons/mi2-mo g/m2-day 1.07 X 10-3 tons/mi2-mo metric tons/km2 -mo 3.5 x 10-' tons/mi2-mo pg/m2-mo g.5 x 103 mg/cm2-mo tons/mi2-mo 28.5 g/m2-day tons/ref-mo 85.5 p or pm m 10-4 14 A 104 A cm 10-8 14 cm bbl 10-4 gal. 55 1 ft3 C:i q1153 ft3 1 28.32 ml in' 6.1 x 102 m ft 3.28 lb g 453.6

194 -201 1;1

APPENDIX D-- GLOSSARY

Acid, freean acid which is unneutralized Albedothe ratio of the amount of electro- by other compounds magnetic radiation reflected by a body to Acid, stearicthe most common fatty acid the amount incident upon it, commonly ex- occurring in natural animal and vegetable pressed as a percentage fats, almost completely colorless and odor- Aldehydeany of a class of organic com- less pounds containing the group R-CHO, in- Acroleina toxic colorless mobile liquid al- termediate in state of oxidation between dehyde with an acrid odor primary alcohols and carboxylic acids Adenocarcinomaa malignant tumorin Alveolus (pl. alveoli)a small, sac-like dila- which the cells are arrar ged in the form tion at the innermost end of the airway, of glands or gland-like structures through whose walls gaseous exchange Adenomaan epithelial tumor, usually be- takes place nign, with a gland-like structure Analysis, factoriala method of evaluating' Adhesionthe attraction of two unlike sub- certain definite integrals by the use of stances gamma functions Adsorptionthe phenomenon by which gases Anaplasia (adj. anaplastic)acondition in are attracted, concentrated, and retained tumor cells in which normal functional and at a boundary aid: face physical differentiation is lost Aerodynamicsa phase of the mechanics of fluids, its study being limited to the re- Anthracosisa disease of the lungs caused actions caused by relative motion between by inhalation and accumulation of carbon fluid and solid, the fluid being limited to particles air in most cases but occasionally broad- Antirachiticopposing or preventing the ened to include any gas development of rickets Aerosola cloud of solid particles and/or Aphid (aphis)a small sucking insect; a liquid droplets smaller than 100p in di- plant louse ameter, suspended in a gas Atelectasisthe collapse of all or part of a Aerosol, bidispersean aerosol in which all lung, with resultant loss of functioning the suspended particles tend to be of two tissue sizes (diameter) Attenuation In physics, any process in Aerosol, monodispersean aerosol in which which the flux density (or power, ampli- all the suspended particles are of nearly tude,intensity, illuminance, etc.)of a equal size (diameter) "parallel beam" of energy decreases with Air, residualthe air that stays in the lungs increasing distance from the energy source after forceful expiration Auscultation (adj. Auscultatory)the act of Air, tidalthe air that is carried to and listening for sounds within the body, us- from the lungs during a respiratory cycle ually with the use of a stethoscope Airwayany part of the respiratory.tract Bacillus subtilika common microorganism through which air passes during breathing found in soil and water and frequently oc- Airway resistanceresistance to the flow of curring as a laboratory contaminant; rare- air in the passages to the lungs ly implicated in causing disease

195 202 Benzo (a) pyrenea polycyclic aromatic hy- Capacity, vitalthe maximum volume of drocarbon which under certain ecum- gas which can be expired from the lungs stances has been shown to produce cancer following a maximum inspiration Bifurcationa site where a single structure Carbonationconversion into a carbonate divides into two branches (which in many cases refers to one or Blistering, osmoticpaint blisters caused by more members of the calcite, dolomite, and moisture picking up water-soluble salts in aragonite groups of minerals) impregna- its passage through the paint film, result- tion with carbon dioxide ing in an ideal situation for osmosis which Carcinogena substance capable of causing represents a tremendous force formation living tissue to become cancerous of blisters Carcinogenesisthe production of cancer Carcinomacancer; malignant growth made Blo'vby the leakage of gas or liquid be- up of cells derived from epithelial tissue tween a piston and its cylinder during op- Carcinomas bronchogeniccancer arising in eration bronchial tissue of the lung Body, asbestosa fiber of asbestos sur- Carcinoma, squamous cellscancer develop- rounded by a deposit of protein material ing from squamous epithelial cells Bronchiectasisa chronic dilatation of a Carcinoma in situa neoplastic entity in bronchial passage which tumor cells are present but the in- Bronchioleone of the finer subdivisions of vasion of normal tissue has not yet taken the bronchial tree place Bronchitisan inflammation of the bronchi, Cardoivascularpertaining to the heart and 'usually manifest clinically by cough and blood vessels the production of sputum Cercospora beticolaa member of the genus Cercospora, which consists of imperfect Bronchitis, chronic--a long-standing inflam- fungi that are leaf parasites with long mation of the bronchi characterized byex- slender multi-septate spores cessive mucus secretion in the bronchial Channel blackcarbon black made by im- tree and manifested by a persistent or re- pingement of a luminous natural gas flame current productive cough. For the pur- against an iron plate from which it is poses of definition, these symptoms must scraped at frequent intervals; properties be present on most days for a minimum of vary widely, but the material has an un- 3 months of the year for at least 2 suc- usually fine state of subdivision and great cessive years (American Thoracic Soci- surface area ety) Chloroplasta specialized body (a plastid) Bronchoconstrictiona diminution in the containing chlorophyll in the cytoplasm of size of the lumen of a bronchus plants; the site of photosynthesis and Bronchus (pl. bronchi)one of the larger starch formation in plants air passages in the lung Cholinesteraseany one of several enzymes Brotha liquid medium for the cultivation that hydrolyze choline esters, occurring of microorganisms most frequently in nervous tissue and the Capacity, forced vital (FVC)the largest blood amount of gas which can be forciblyex- Cilium (pl. cilia)small, hairlike process at- pired from the lungs following a maximal tached to a free surface of a cell, capable inspiration of rhythmic movement Capacity, functional residual (FRC)the C'earancethe removal of material from volume of gas remaining in the lungs at the body or from an organ the resting end-expiratory level Clinkerkiln-fired limestone from which commercial cement is made Capacity, total lung (TLC)the volume of Coalescencein cloud physics, the merging gas contained in the lungs at full inspira- of two water drops into a single larger tion drop 196 -903 Coefficient, absorptionthe fractional rate Coryzctan acute catarrhal conditiOn of the at which flux density of radiation decreases nasal mucous membrane with profuse dis- by absorption with respect to the thick- charge from the nostrils ness of the absorbing medium traversed Criteria, air qualitya compilation of the Coefficient, extinctionthe sum of the ab- scientific knowledge of the relationship be- sorption coefficient and the scattering co- tween various concentrations of pollutants efficient for a medium that both absorbs in the air and their adverse effects and scatters radiation Cryolitea mineral fluoride consisting also Coefficient, scatteringthe fractional rate of sodium and aluminum in the transmission of radiation through a Cuticlea varnish-like layer covering the scattering medium (as of light through surface of a leaf fog) at which the flux density of radia- Cytoplasmthe protoplasm of a cell(ex- tion decreases by scattering in respect to cluding that of the nucleus) the thickness of the medium traversed Dead space, anatomicthat part of the air- Coh unita measure of light absorption by way occupied by gas which is unavail- particles, defined as that quantity of light able (by its location) to take part in oxy- scattering solids producing an optical den- gen-carbon dioxide exchange through the sity of 0.1 walls of the alveoli Collagen--a fibrousprotein forming the Dead space, physiologicthe volume of gas main supportive structure of connective within the alveoli which does not partici- tissue pate in the oxygen-carbon dioxide ex- Collector, cyclonica centrifugal fraction- change through the walls of the alveoli ator in which a vortex of air thrcws par- Dehydrogenaseany one of various enzymes ticles out of a stream, where they collect which accelerate the removal of hydrogen or stick to the surface of a container from metabolities and its transfer to other Comminuteto break or crush into small substances, thus playing an important role pieces in biological oxidation-reduction processes Concentration- -the total mass (usually in Deliquesceto dissolve gradually and be- micrograms) of the suspended particles come liquid by absorbing moisture from contained in a unit volume (usually one the air cubic meter) at a given temperature and Densitythe amount of matter per unit vol- pressure; . sometimes,the concentration ume, usually expressed in grams per cubic may be expressed in terms of total num- centimeter ber of particles in a unit volume (e.g.,Density, opticalthe degree of opacity of parts per million) ;concentration may any translucent medium; the common loga- also be called the "loading" or the "level" rithm of the ratio of the initial intensity of a substance concentration may also per- of light to the intensity of transmitted or tain to the strength of a solution reflected light Coniferbelonging to the coniferales order, consisting primarily of evergreen trees Desorptionthe release of a substance which and shrubs has been taken into another substance by Consolidationthe process by which a dis- a physical process or held in concentrated eased lung passes from an aerated col- form upon the surface of another sub- lapsible state to one of an airless solid stance; the reverse of absorption or ad- consistency because of accummulation of sorption exudate Desquamateto cast off epidermis in shreds Contrastin visual range theory, the ratio or scales; to peel off in sheets or scales of the apparent luminance of a target mi- Deviation,standardgeometric (og) a nus that of its background to the apparent measure of dispersion of values about a luminance of the background geometric mean; the portion of the fre- Conurbationa great aggregation or con- quency distribution that is one standard tinuous network of urban communities geometric deviation to either side of the

197 geometric mean accounts for 68% of the Endocytosisa conditionor disease arising total samples from the inclusion within a cell ofma- Deviation, standard nor malameasure of terial which does not properly belong there dispersion of values about a mean value; Entomologyzoology dealing only with in- the square root of the average of the sects squares of the individual deviations from Epidemiologya science dealing with the the mean factors. involved in the distribution and Dextranawater-solublepolymerused frequency of a disease process in apopu- therapeutically as a plasma substitute lation Diameter, count median (CMD)thegeo- Epidermisthe outermost layer of skin in metric median size of a distribution of animals; any integument particles, based on a numerical count Epiglottisa plate of cartilage whichcovers Diameter, mass median (MMD)thegeo- the entrance to the larynx during swal- metric median size of a distribution ofpar- lowing, thus preventing foodor fluid from ticles, based upon a weight (usually de- entering the windpipe rived from a Stokes' Diaineter) Epithelium--a closely packed sheet ofcells Diameter, Stokes'the diameter thata unit arranged in one or more layers, covering density particle of spherical shape would the surface of the body and lining hollow have if it behaved the sameas the particle organs being studied Epithelium, columnara type of epithelium Dichotomousdividing in succession into composed of tall, prismlike cells pairs; showing a dual arrangement Epithelium, spuamousa type of epithelium Distalfurthest or most remote from the composed of plate-like cells median line of the body, from the point Ergometeran instrument whichmeasures of attachment, or from the origin; periph- work done, e.g., by muscle contraction;a eral (cf. proximal) dynamometer Diverticulum (pl. diverticula)a pouch or Evaginateto turn inside outor protrude cul-de-sac of a hollow organ by eversion Dosimetrythe accurate measurementand Extrapolateto project data intoan area determination of (medicinal) doses not known or experienced, and arrive at Dyspneadifficult or labored breathing knowledge based on inferences of conti- Earth, diatomaceousa chalky materialused nuity of the data as a filter aid, an absorbent, a filler, an Fibrosisthe development of fibros tissue; abrasive, and as thermal insulation sclerosis Edemaa condition due to thepresence of Filiformhaving the shape ofa thread or abnormally large amounts of fluid in the filament intercellular tissue spaces of the body Flocsomething occurringinindefinite Effluentsomething that flows out, suchas masses or aggregates a liquid discharged as a waste Fluorosisa pathologic condition resulting Elutionthe process of washing out,or re- from excessive intake of fluorine moving with the use of a solvent Fluorsparthe mineral fluorite Elutriator, fractionala tractional sampler Fluxa flowing or discharge of fluid;a sub- which removes coarse particles fromthe stance used to promote fusion (as byre- air by gravity settlement moving impurities) of metalsor minerals; Emphysemaa swelling due to thepresence the rate of transfer of fluid, particles,or of air, usually excessor additional air. energy (as radiant energy) across a given The term is usually used to refer topul- surface monary emphysema Fumean aerosol formed by the condensa- Emphysema, pulmonarya conditionin tion of vapors as they cool which there is overdistension ofair spaces Gastricpertaining to the stomach and resultant destruction of alveoliand Gastrointestinalpertaining to the stomach loss of functioning lung tissue and intestines 198 Goblet cella type of epithelial cell contain- Interstitialpertaining to or situated in the ing mucus and having the shape of a flask space between cells or goblet In vitroin a test tube or other artificial Gravimetricof or relating to measurement environment by weight In vivowithin a living body Hazefine dust or salt particles dispersed Isotherma line on a chart representing through a portion of the atmosphere; the changes of volume or pressure under con- particles are so small that they cannot be ditions of .constant temperature; or lines felt or individually seen with the naked on a map connecting points having the eye, but they diminish horizontal visibil- same temperature ity and give the atmosphere a character- Ketoneany of a class of organic compounds istic opalescent appearance that subdues that are characterized by a carbonyl group all colors attached to two carbon atoms, usually con- Hematitethe mineral iron oxide; Fe203 tained in hydrocarbon radicals or in a Histaminea substance which produces di- single bivalent radical, similar to alde- latation of capillaries and stimulates gas- hydes but less reactive tric secretion, occurring in both animal and Lacrimation (lachrymation)tear forma- vegetable tissues; p-imidazolethylamine tion, especially in excess Histograma graphical representation us- Langleya unit of energy per unit area, ing a series of bars commonly employed in radiation theory Histologythe study of the anatomy of tis- and equal to one gram-calorie per square sues and their microscopic cellular struc- centimeter ture Larynxthe organ concerned with the pro- Hydrocarbona compound containing only duction of the voice, situated at the upper hydrogen and carbon. This group is sub- end of the trachea divided into alicyclic, aliphatic, and aro- Lesionan injury or other circumscribed matic hydrocarbons according to the ar- pathologic change in a tissue rangement of the atoms and the chemical Logarithma number which represents the properties of the compounds. power to which a given number must be Hygroscopicreadily absorbing and retain- raised to produce another given number ing moisture from the atmosphere Lumenthe inner space of a hollow organ Hyperplasia(adj.hyperplastic)anin- or tube crease in the number of cells in and bulk L7copodiuma genus of club-moss; a pow- of a tissue, with retention in normal func- der ("vegetable sulfur") used to prevent tion and cellular structure the agglutination of pills in a box or as Illuminationthe process in which light is a dusting powder brought to some surface or object Lympha fluid that is collected from the Impactor, cascadean instrument which tissues throughout the body, flows in the employs several impactions in series to lymphatic vessels, and is eventually added collect successively smaller sizes of par- to the bloodstream ticles Lymphomaany neoplasm developing from Incidencethe rate at which a certain event lymphatic tissue or disease occurs Macrophagea large phagocytic cell found Insolation the rate at which direct solar rain the connective tissue, especially in areas diation (of all wavelengths) is delivered of inflammation to a unit area of a horizontal surface, us- Malignancysomething which tends to be- ually at or near ground level come progressively worse and if un- Insulationthe prevention of the transfer checked could result in death of energy between two conductors by sepa- Mastoiditisan inflammation of the skull ration of the conductors with a non-con- bone behind the ear ducting material; or, the non-conducting Mean, geometric (M.)a measure of cen- material itself tral tendency for a log-normal distribution; 1) 4 I, a. 199 the value, in a given set of samples, above Nephelometeraphotometricinstrument INNich 50% of the values lie for the determination of the amount of Meatusa natural body passage, particular- light transmitted or scattered by a sus- ly the external opening of a canal pension of particles Mesotheliomaa tumor which develops from Nodea circumscribed swelling the lining of a coelomic body cavity Node, lymphone of many accumulations of Metaplasia (adj. metaplastic)a change in lymphatic tissue situated throughout the the cells of a tissue to a form which is not body normal for that tissue Nomograma graph that enables one to Metastablemarked only by a slight margin read off the value of a dependent variable of stability with the use of a straightedge, when the Meteorological range (standard visibility, values of two or more independent vari- standard visual range)an empirically ables are known consistent measure of the visual range of Nucleationthe process of particle growth a target; a concept developed to eliminate through collection around a nucleus from consideration the threshold contrast Nucleus (condensation nucleus)a particle and adaptation luminance, both of which in the size range from 0.1p to 1p which vary from observer to observer serves as a nidus on which water or other Morbiditythe occurrence of a disease state vapors in the air can condense to form Morphologya branch of biology dealing liquid droplets with the structure and form of living or- Olefin --a class of unsaturated aliphatic hy- ganisms Arocarbons of the general formula C.11. Mortalitythe ratio of the total number of Olfactorypertaining to the sense of smell deaths to the total population, or the ratio Ophthalmicpertaining to the eye of the number of deaths from a given dis- Otitisan inflammation of the ear ease to the total number of people having Palisade tissuea layer of columnar cells that disease rich in chloroplasts found beneath the up- Motion, Brownianthe rapid random mo- per epidermis of foliage leaves tion of small particles due to bombard- Parameteran arbitrary constant which ment by surrounding molecules which are characterizes a mathematical expression in thermal motion Parenchymathe specific or functional tis- Mucina glycoprotein or mucopolysaccha- sue of a gland or organ, as opposed to its ride secreted by mucous glandular cells supporting framework Mucopurulentpertaining to an exudate (or Particleany dispersed matter, solid or liq- sputum) that is chiefly purulent (pus) but uid, in which the individual aggregates also contains significant amounts of mucus are larger than single small molecules Mucoviscidosiscystic fibrosis (about 0.0002p in diameter), but smaller Mucus (adj. mucous)the clear viscid se- than about 500p in diameter cretion of a mucous membrane Particulateexisting in the form of minute Muratpertaining to the wall of a cavity separate particles Mustard gasan irritating and toxic volatile Pathogenesisthe production or the mode liquid used as a weapon in World War 1; of origin and development of a disease dichloroethyl sulfide condition Naris (pl. nares)a nostril or other open- Pathologythe study of the essential nature ing into the nasal cavity of disease, particularly with respect to the Nasopharynx the part ofthe pharynx structural and functional changes in or- (throat) lying above the level of the soft gans and tissues palate Peritoneum-the membrane lining the ab- Nebulizeto reduce to a fine spray dominal cavity and investing the viscera Necrosisloatlized death of cells Phagocytea cell that has the power of in- Neoplasm any abnormal growth, such as gesting microorganisms and other small a tumor particles 200 Phagocytosis the ingestion of a microor- and virga in that it must reach the ground ganism or other small particle by a phago- Precipitator, electrostatican apparatus for cyte the removal of suspended particles from Pharynxthe upper expanded portion of the a gas by charging the particles and pre- alimentary canal lying between the mouth, cipitating them by applying a strong elec- the nasal cavities, and the beginning of tric field the esophagus; the throat Predatoran organism living by preying on Photometeran instrument for measuring other organisms luminous intensity, luminous flux, illumi- Prevalencethe number of cases of a dis- nation, or brightness by comparison of two ease at a given time unequal lights from different sources Prodromethe symptoms preceding the ap- Photomicrographa photograph of a mag- pearance or recognition of an actual dis- nified image of a small object ease state Photosynthesisthe formation of carbohyr Proteinosisthe accumulation of protein in drate from carbon dioxide and water in excess in the tissues the presence of chlorophyll and light, in Proteinosis, alveolara chronic progressive plant tissues lung disease characterized by the accumu- Physiologya science which studiesthe lation of granular proteinaceous material function of a living organism or its parts in the alveoli Phytotoxicharmful to plant materials Proximalnearest to the center of the body Plasmolysi:tthe shrinking of the cytoplasm or the point of origin (cf. distal) away from the wall of a living cell due to Radioautograph (autoradiogram)a radio- water loss by osmotic action graphic portrayal of an object or organism Plethysmographan apparatus for the de- made by the inherent radioactivity of the termination and recording of a change in object or organism the size of an organ or limb or body Ralean abnormal respiratory sound heard Pneumococcus (pl. pneumococci)a bacte- in auscultation of the chest rial organism which most often infects the Ratio, standardized mortalitythe ratio of lung and is a common cause of pneumonia; the number of deaths observed in a given Diplococcus pneumoniae population over a given period of time to Ptieumoconiosisa fibrous reaction in the the number of deaths expected to occur lungs, caused by the retention of certain in the given population over the same pe- inhaled dusts in the lungs riod of time if the given population be- Pneumonitis a general term for inflamma- hayed as any other group of similar com- tion of the lung position would during that same period Pneumotachygraphan instrument used to Reflectometera photometric or electronic determine the force and velocity of re- device for ineasuring the reflectances of spired air light or other radiant energy Polystyrenea clear, colorless polymer of Regressiona trend or shift toward a mean. styrene, an unsaturated hydrocarbon of A regression curve or line is thus one that the form C6115CH=C11, best fits a particular set of data according Potentiationsynergism, as between two to some principle agents which together have a greater ef- Rhinitisan inflammation of the nasal mu- fect than the sum of their effects when cous membrane acting_ separately Rhinorrhea . "runny nose" Precipitationany or all of the forms of Rhonchus (pl. rhonchi)a dry, coarse sound water particles, whether liquid or solid, usually originating from partial obstruc- that fall from the atmosphere and reach tion in a bronchial tube the ground. It is a major class of hydro- Scattering, Mieany scattering produced by meteor, but is distinguiPhed from cloud, spherical particles, without specific regard fog, dew, rime, frost, etc. in that it must to the comparative size of radiation wave- "fall," and is also distinguished from cloud length or particle diameter '1: 208 201 Scattering, Rayleighany scatteringproc- Tanninany one of a group of solubleas- ess produced by spherical particles whose tringent complex phenolic substances that radii are smaller than about one-tenth the are widely distributed in plants wavelength of the scattered radiation Terpeneany one of a class of isomeric hy- Sigmoid curvea "bell-shaped"curve serv- drocarbons of the prototype Colin that ing as a prototype for the normal distri- are found in many essential oils, butespe- bution of data about a mean cially from conifers; may also refer toany Silicosisa type of pneumoconiosis caused of various compounds derived fromter- by inhalation of silica dust and character- pene hydrocarbons or closely related to ized by silica-containing nodules ofscar them tissue in the lung parenchyma Tipburna disease of the potato, lettuce, and Sorptionthe generalized term for themany other cultivated plants, characterizedby phenomena commonly included under the burning or browning of the tips andmar- terms adsorption and absorption, when the gins of the leaflets and caused by lossof nature of the phenomenon is unknownor water due to excessive heat and sunshine indefinite Toxicologythe study of poisons, including Spirometeran instrument for themeasure- their preparation, identification, physio- ment of the volume of gas respired by the logic action, and antidotes lungs Tracheawindpipe; the airway extending Sporea reproductive element ofmany from the larynx to the origin of thetwo lower organisms mainstem bronchi Squamous resemblingorcoveredwith Tracheobronchitisan inflammation of the scales trachea and bronchi Standards, air quality levels of air pollut- Turbidityin meteorology, any condition in ants which cannot legally be exceededdur- the atmosphere which reduces its ing a specific time ina specific geographi- trans- cal area parency to radiation, especially to visible radiation Stasisthe slowing downor cessation of the normal flow Tyndallometeran instrument thatmeas- Stigmathe part of the pistil ofa flower ures suspended particle concentration by which receives the pollen granulesand on the amount of light scatteredout of a which they germinate beam Stokes' Lawa law in physicsstating that Uttrafitterabiecapable of being separated the force required tomove a sphere by a dense filter which is used forthe through a given viscous fluidat a low uni- filtration of a colloidal solution holding form velocity is directly proportionalto back the dispersed particles but notthe the velocity and radius of thesphere liquid Stoma (pl. stomata) tea small openingin the Updraftan upward movement of airor epidermis of a plant other gas Subcutaneousbeneath the skin Ventilation, minutethe total volume ofgas Supercool to cool below the freezingpoint respired in one minute, i.e., the tidalvol- without solidificationor crystallization ume multiplied by breaths per minute Supersaturation-- a condition ofcontaining VisibilityIn United States weather observ- an excess of some material or force,over ing practice, the greatest distancein a the amount required for saturationnor- given direction at which it is just mally possible to see and identify with the unaidedeye Synergisma situation in which thecom- (a) in the daytime, a prominent darkob- bined action of twoor more agents acting ject against the sky at the horizon,and together is greater than thesum of the (b) at night, a known, preferablyunfo- action of these agents separately cused, moderately intense lightsourea. Systemicrelating to the bodyas a whole, After visibilities have beendetermined rather than to its individual parts around the entire horizon circle, theyare 202 --209 resolved into a single value of prevailing observer's threshold contrast at the mo- visibility for reporting purposes. ment of observation. Visual rangethe distance, under daylight Volume, forced expiratory (FEV)the vol- conditions, at which the apparent contrast ume of gas forcibly exhaled over a given between the specified type of target and time interval (usualtj, measured in sec- its background becomes just equal to the onds)after maximum inspiration, e.g., threshold contrast of an observer; to be FEV1.0 for this mecsurement over a 1.0 distinguished from the night visual range. second period. The visual range is a function of the at- Volume, minutesame as minute ventilation mospheric extinction coefficient, the albe- Volume, tidatthe volume of gas inspired or do and visual angle of the target, and the expired during each respiratory cycle. AUTHOR INDEX

Ackley, C., 94 Brown, J. H., 118 Day, J. A., 11 Agnese, G., 162, 172-173 Brown, M. C., 137 De Groot, I., 99, 101 Ahlquist, N. C., 56, 57, 59 Bryson, R. A., 42, 43 Deily, J, G., 18 Albert, R. E., 122 Buck, S. F., 157, 172 De Maio, L., 19 Alcocer, A. E., 26 Bunyard, F. L., 99 Dennis, W. L., 118 Altshuler, B., 113, 117, 118 Burgess, F., 130, 131, 136 Dessens, J., 18 Amberg, H. R., 106 Burgess, S. E., 151, 171 De Treville, R. T., 135 Amdur, M. 0., 113, 131, 132, 133,Burn, J. L., 157, 158, 159, 164, 172- Devir, S. E., 131 134, 136 173, 174 Diamond, J. R., 149, 155, 156, 171, Andersen, A. A., 17, 19 Bye, W. E., 167 172 Anderson, D. 0., 150, 161, 104, 165, Dickerson, R. C., 20, 22 173-174 Cadle, R. D., 8, 10 Diem, M., 17 Anderson, P. J., 92 Cambell, J. A., 137 Djordjevic, N., 11 Andrea, J., 140 Capps, R., 135 Dobrogorski, 0. J., 130 Angel, J. H., 168, 175 Carey, W. F., 69 Dohan, F. C., 164 Angstrom, A. K., 38, 39, 43, 53 Carnes, W. H., 141 Doherty, R. E., 26 Antler, M., 69 Cartwright, J., 69, 71 Douglas, J. W. B., 165, 173-174 Antweiler, H., 121 Casarett, L. J., 122, 123 Downs, W. L., 122 Arnett, L. C., 122 Cassel, E. G., 150, 154, 156, 171, 172 Draftz, R. G., 18 Ashworth, J. R., 41, 44 Cefis, F., 139 Draper, P., 26 Auerbach, 0., 141 Chaney, A. L., 26 Drinker, P., 8, 113, 117, 118, 132 Axt, C. J., 19 Changnon, S. A., Jr., 41 Drolette, B. M., 153, 154, 171 Ayer, H. E., 137 Charlson, R. J., 19, 54, 55, 56, 57, 59 Du Bois, A. D., 133 Chass, R. L., 24 Baetjer, A. M., 132 Christofano, E. E., 135, 136 Balzer, J. L., 137 Clark, J. G., 22 Eckel, 0., 39 Barfinkel, L., 141 Clark, W. E., 23, 54 Edmonds, S. M., 106 Barlett, F. E., 106 Clemo, G. R., 137 Elliott, A., 166 Bates, D. V., 163,173 -174 Coblentz, H., 39 Ellis, 0. B., 66, 67, 68 Baulch, D. M., 19, 37 Coffin, D. L., 129 Ellison, J. M., 22 Baumberger, J. P., 117 Collet, A., 123 Epstein, S. S., 140 Bechmann, H., 117 Collins, G. F., 106 Erdhardt, C., 153, 154, 171 Becker, W. IL, 165, 173-174 Conner, W. D., 53 Belton, J., 154 Cook, K. M., 118 Falk, H. L., 120, 134, 137, 138, 141 Berge, H., 94 Cooley, R. N., 132 Faoro, R. B., 16 Biersteker, K., 168, 176 Cooper, W. C., 137 Faulds, J. S., 139 Black, S., 118 Copson, H. R.-. 66, 67, 68, 69 Fensterstock, J. C., 16 Blifford, I. H., 11 Corn, M., 6, 8, 19, 132, 133 Ferris, B. G., Jr., 164, 173-174 Bohne, IL, 91, 92, 94 Conghanower, D. R., 136 Field, F., 153, 154, 171 Bonser, G. M., 139 Cralley, L. J., 137 Fieldner, A. C., 117 Boren, H. C., 135 Creasia, D. A., 133 Findeisen, W., 114, 115, 119 Bowden, A. T., 26 Crider, W. L., 26 Finn, J. L, 117 Bownes, K., 105 Crowley, D., 154, 155 Firket, J., 150 Bradley, W.. 152, 154, 156, 171, 172 Cuffe, S. T., 5 Fischer, W. H., 19 Brandt, P., 17 Cullumbine, H., 130, 132, 136 Fish, B. R., 10 Brasser, L. J., 150, 153, 158 Czaja, A. T., 91, 92 Fisher, M., 121 Braverman, M. M., 153, 154, 171 Flesch, J., 132 Brieger, H., 122 Dalhamn, T., 121, 122, 135 Fletcher, C. M., 168, 175 Brier, G. W., 41 Darley, E. F., 90, 91, 92, 93 Fochtman, E. C., 71 Briscoe, W., 122 Dantrebande, L., 117, 119, 133, 135 Foster, K. E., 17 Brooke, A. G. F., 71 Davies, C. N., 111, 117, 118, 119,Frank, E. R., 20, 23 Brown, C. E., 117 121, 122, 123, 132, 135, 136 Frederick, R. H., 41 Brown, D. A., 157,172 Davies, R. I., 157, 171-172 Friedlander, S. K., 54, 58 204 Gates, D. M., 38 Ide, H. M., 20' Long, J. E., 135, 136 Georgii, H. W., 41 Imada, M., 57 Ludwig, F. L., 19 Gibb, F. R., 117, 119, 121 Ludwig, J. H., 42, 43 Gilbert, J., 69 Jacobs, M. B., 65, 69, 153, 154, 171 Lunn, J. E., 166 Giles, C. H., 69 Jacobson, J. S., 93, 94 Lynch, J. R., 137 Gincr, R., 40 Jennings, 0. E., 94 Girorer, W., 117 Jens, W., 24, 25 Mac Phee, R. D., 26 Glasser, M., 154, 155 Johnstone, H. F., 136 Goetz, A., 6, 10, 19, 58, 59,106 Magill, P. L., 95 Jones, E. E., 26 Mantel, N., 140 Gong, W. K., 26 Joosting, P. E., 151, 153, 158 Gore, A. T., 151, 171 Manzhenko, E. G., 167, 174,-175 Joslii, S., 140 Marcus, S. C., 167 Graf, P., 132 Junge, C. E., 11, 23, 53, 54 Graff-Baker, C., 71 Mark, H. L., .106 Jurksch, G., 17 Markul, I., 138 Greenburg, L., 68, 69, 153, 154, 171 Jutze, G. A., 17 Greenwood, D. A.. 95 Markush, R. E., 157 Greenwood, J. A., 69 Martin, A. E., 152, 153, 156, 171- Kaiser, E. R., 25, 107 Greezuitay, L. A., 139 172 Kakis: F., 105 Gross, P.. 111, 123, 135 Mateer, C. L, 40 Kallai, T., 58, 59 Grote, lVi. J., 139 McCaldin, R. 0., 167 Kanitz, S., 162, 172-173 Gruber, C. W., 17 McCarroll, J., 150, 154, 156, 171- Katz. M., 17, 22 172 Gucker, F. Tu 19 Keagy, D. M., 21 Guderian, R., 92 McConnell, W. J., 117 Keenan, R. G., 137 McCormick, R. A., 19, 37, 38, 42, Kemeny, E., 21 43 Kemnitz, D. A., 5 McCrone, W. C., 18 Haddow, A., 139 Kenrick, G. W., 39 McCune, D. C., 93, 94 Hagstrom, R. M., 159, 161, 172-173 Kerka, W. F., 107 McDermott, M., 133 Haines, G. F., Jr., 20 Klarman, H. E., 84 McKee, H. C., 105 Hamilton, R. J., 17 Kline, D. B., 41 McMullen, T. B., 16 Hammond, C., 130 Knowelden, J., 166, 168, 174-175 McNerney, J., 119 Hammond, E. C., 141 Kolb, L. H., 139 Meeker, G. 0., 11 Hand, I. F., 40 : Kolesnichenko, T. S., 139 Meetham, A. R., 40, 41 Handyside, A. J., 166, 168, 174-175 Korff, F., 39 Megaw, W. J., 23 Harris, J., 69 Kotin. P., 120. 132, 136, 137, 138, Meller, H. B., 69, 71 Harris, W. B., 17 141 Metnieks, A. L., 23 Harrison, L E., 95 Krahl, V.E., 111 Michelson, I., 81 Hatch, T. F., 8, 111, 119, 120, 123 Kramer, G. D., 21, 22 Middleton, W. E. K., 51, 52 Haythorn, S. R., 131 Kreichelt, T. E., 5 Mie, G., 10, 55 Helwig, H. L, 26 Kuepel, R. E., 138 Miller, A., 135 Hemeon, W. C. L., 17, 20 Kurland, L. T., 156 Miller, E. C., 137 Hendrix, W. G.. 23 Kuschner, M.. 140 Miller, P. M., 94 Hess, V. F., 40 Miller, W. S., 111 Hewson, E. W., 17 La Belle, C. W., 135, 136 Milley, P. S., 123 Hilding, A. C., 122 Lainhart, W. S., 137 Miner, M. L., 95 Hill, A. C., 93, 94 La Mer, V. W., 118 Mitchell, J. M., Jr., 43 Hill, I. D., 148, 168, 175 Landahl, H. D., 114, 118 Mitchell, R. I., 111 Hitchcock, A. E., 93, 94 Landau, E., 159, 162, 164, 172-174 Moll, A. J., 136 Hodkinson, 3. R., 63 Landsberg, H., 38, 39, 40, 41 Morrow, J., 105 Hoffman, P., 19 Langer, G., 71 Morrow, P. E., 111, 118, 119, 121 Holbrow, G. L., 71 Larrabee, C. P., 66, 67, 68, 69 Mountain, I. M., 150, 156, 171-172 Holden, F. R., 95 Lawther, P. J., 153, 168, 169, 171, Mountain, J. D., 149, 156, 171-172 Holland, W. W.,162;163, 166, 167, 175 Mueller, P. K., 26, 57 172 - 173,174 -175 . Le Clem, E., 69, 81 Holma, B., 122 Lee, G., 113 Nadel, .1. A., 17, 132 Holzworth, G. C., 51 Lee, R. E., Jr., 19, 26 Nader, J. S., 19 Horning, E. S., 189 Lehmann, C., 118 Nagelsehrnidt, G., 69 Horton, R. J. M., 164 Lehmann, K., 117 Nan, C. A., 132 Horvath, H., 19, 54, 56, 57,59 Lemke, E. E., 12 Neal, J., 132 Hudson, J. D., 66, 67 Leonard, A. G., 154, 155 Nelson, N., 113, 117, 118, 122 Hueper, W. C., 187 Linnell, R. H., 105 Neuberger, H., 40 Huey, N., 81 Lippmann, M., 17, 122 Ney, F. G., 118 Humphreys, W. 3., 43 Lloyd, T. C., 167 Noll, K. E., 55, 57 Hurd, F. K., 23 Lodge, J. P., 19, 20, 23 Nussbaum, R., 92 Nth i 1 '1. .41.4 O'Connor, J. J., Jr., 81 Rich, T. A., 23 Stagg, J. M., 39, 40 O'Konski, C. T., 19 Ridker, R. G., 84 Stalker, W. W., 20, 22, 101 Orr, C., 23 Rinehart, W. E., 135 Stanley, T., 138 Ortiz, H., 39' Robbins, R. C., 10 Steiner, P. E., 138 Ott, R. R., 105 Robison, C. B., 101 Steinhauser, F., 39 Owens, J. S., 117 Robinson, E., 19, 51, 52, 53, 58 Steinhubel, G., 91 Ozolins, G., 12 Robinson, N., 38 Shembridge, V., 132 Robson, C. D., 17 Stern. A. C., 19, 51, 52, 53, 58, 72 Paocagnella, B., 167, 174-175 Roderick, W. R., 105 Stevenson, H. J. R., 19 Pack, M. R., 93, 94 Roesler, J. R., 19 Stewart, M. J., 139 Pajenkamp, H., 92, 93 Ronald, G., 18 Stocks, P., 157, 171-172 Palm, P. E., 119 Rose, A. H., 24 Stoeber, W., 17 Palmes. E. D., 113, 117 Rossano, A. T., 105 Stokinger, H. E., 129, 130, 134 Parish, S. B., 89 Bowling, H., 26 Stone, R. W.. 162, 163, 167, 172- Park, J. C., 21 173, 174-175 Parker, A., 71 SaMotti, U., 139 Stout, A. P., 141 Pascua, M., 137 Saito, Y., 117 Stout, G. E., 42 Pate, J. B., 19 Salem, H., 130, 132, 136 Stratmann, H., 93 Patterson, H. S., 117 Samuels, S. W., 99, 101 Strauss, W., 23 Patterson, R. K., 19, 26 Sanderson, H. P., 15, 22 Strethlow, C., 122 Pattie, R. E., 130, 131, 136 Sanyal, B., 66, 69 Sullivan, J. L., 22 Paulus, H. J., 154 Sauberer, F., 39 Sutton, 0. G., 106 Pavanello, R., 167, 174-175 Sawicki, E., 138, 140 Swartztrauber, P., 19 Payne, W. W., 138 Sawyers, L. A., 113 Peirce, G. J., 89, 91 Sayers, R. R., 117 Pemberton, J., 157, 158, 159, 164, Scheffer, F., 93 Tabershaw, I. R., 137 172-174 Schilling, F. J., 165, 173-174 Tabor, E. C., 71, 72, 139, 140 Pesarin, F., 167, 174-175 Schnurer, L., 131 Taylor, J. R., 26 Peterson, C. M., 54 Schonbeck, H., 92 Tebbens, B. D., 72 Peterson, J. T., 43 Schrader, J. H., 39 Telford, J. W., 42 Petrie, T. C., 72 Schrenk, H. H., 134 Thomas, B. G. H., 117 Petrilli, F. L., 162, 172-173 Schueneman, J. J., 101 Thomas, M. D., 93, 94 Pfitzer, E. A., 123 Schusky, J., 99 Thompson, R. M., 117 Phillips, P. H., 95 Scott, J. A., 152, 171 Tice. E. A., 65, 71 Pickard, H. B., 19 Scott, W. E., 106 Tinker, C. M., 168, 176 Pilat, M. J., 54, 56 Selikoff, L J., 130 Tomashefski, J. F., 112 Pitts, J. N., Jr., 19 Seltser, R., 162, 163, 167, 172-173, Tourangeau, F. J., 118 Plotkin, T., 113 174-175 Tourin, B., 81 Policard, A., 123 Sensenbaugh, J. D., 17 Toyama, T., 162, 167, 172-173, 174- Pollack, L. W., 23 Seriff, N. S., 153, 171 175 Potter, J. G., 41 Shabad, L. M., 139 Tracewell, T. N., 118 Pregermain, S., 123 Shaddick, C. W., 151, 171 Transtrum, L. C., 93, 94 Preining, 0.,11, 58, 59 Shaffer, N. R., 12 Tremer, H., 132, 136 Preston, R., St. J., 66, 69 Shaver, J., 135 Tufts, a J., 23 Prindle, R. A., 164, 167,173 -174 Sheesley, D., 11 Turk, A., 105, 106 Przeznecic, E., 93 Shelden, J. M., 17 Pueachel, R. F., 10, 19, 64, 55, r6, Sheleikhovskii, G. V., 37, 88, 39 Uhlig, H. H., 80 59 Sheppard, P. A., 37 Pnrvance, W. T., 23 Underhill, D. W., 132, 136 Shubik, P., 189 Upham, J. B., 68 Pybus, F. C., 137 Shupe, J. L, 95 Pylev, L. N., 139 Sievers, F. J., 94 Silverman, L., 23, 113 Valko, P., 43 Quebedeaux, W. A., 105 Sisson, L. B., 69, 71 Van Haut, H., 193 Skidmore, J. W., 69 Van W.ijk, A. M., 117 Raymond, V., 92 Slatgr, R. W., 17 Venezia-, R., 12 Reed, 3. I., 153, 164, 171 or, Smith, B. M., 7:0 Verma, M. P., 165, 173-174 Rees, W. H., 71 ,72 Smith, R., 16 Vernon, W. H. J., 65 Rehm, F. R., 24, 25 Smith, W. S., 27, 101 Verssen, J. A., 12 Reid, D. D., 162, 163, 165, 167, 172- Speizer, F. E., 168, 175 Vintinnnr, F. J., 182 \ 178, 174-175 Spiegelman, J., 122 Volz, F., 19, 87, 48 Reid, L., 185 Sprague, H. A., 159, 161, 172-178 Von Zuilen, D., 150, 153, 158 Rich, S., 94 Spunky, K., 20 Vorwald, A. J., 134

206 -213 I Wagman, J., 10, 19, 26 Weinstein, L. H., 93, 94 Wohlers, H. C., 106 Wagner, W. D., 130 Weisbrod, B. A., 84 Wolfson, P., 122 Walkenhorat, W., 117, 119 Went, F. W., 53 Wright, G. W., 167 Waller, R. E., 71, 165, 169, 173 -174 Wentzel, K. F., 92 Wynder, E. L., 19 Walter, E. W., 150, 156, 171-172 West, P. W., 19 Walther, J. E., 106 Yancey, A. R., 113 Whitby, K. T., 23 Yant, W. P., 117 Walton, W. H., 17 Wicken, A. J., 162 Wang, C. S., 54, 58 Yarmus, L., 113, 117, 118 Williams, J. D., 99 Yocom, J. E., 69, 71 Warren, W. V., 71, 72 Williamson, J. B. P., 69 Watanabe, H., 154, 167, 171, 174- Wilms, W., 93 Zeidberg, L. D., 101, 156, 159, 161, 175 Wilson, I. B., 118 164, 172-173, 173-174 Wedd, C. D., 131 Winkelstein, W., 158, 172-173 Zickmantel, R., 64, 173-174 Weibel, E. W., 114 Wiseley, D. V., 137 Zwi, S., 132

::214. .207 SUBJECT INDEX

A C Copper alloys Canada corrosion of, 6869 Acrolein toxicity, 135, 186 morbidity studies, 163, 164, 173 Corn oil particles Adhesion properties, 8-9 Cancer deposition, 118 Adhesive dustfall collectors, 17 lung, 137, 141, 157-162 Corrosion of metals, 65-69, 72-74 Adsorbed substances mortality, 157, 160-162 Costs of air pollution damage, 79- discussion of, 130 stomach, 158, 161-162 84 Adsorption Carbon black Cotton role in odors, 107 toxicity of, 132 soiling and deterioration of, 72, role in toxicity, 130 Carbon particles 74 Aerodynamic factors toxicity, 135 Crust formation on plants, 89-93 respiratory tract, 113-114, 115- Carcinogenic hydrocarbons, 137- Cyclonic collectors, 17 116 142 Aerosols Carcinogens D pulmonary effects, 131-137 discussion of, 137-142 Deposition reduction of toxicity, 130-131 Cascade impactors,. 17, 19 respiratory system, 112-119 toxicity, 129 Deposition (dust) on vegetation, Age Cement plants emissions from, 24, 25-26 89-96 relationship to mortality, 148, Cement-kiln dust, 89-93 Desorption 151, 158, 160 Channel black effects 'resp. tract, odorants, 106-108 Air pollution episodes, 15, 150-154 132 Deterioration of materials, 65-74 Alveolar deposition, 119 Chemicals Detroit Ammonia toxicity, 122,135 odors from, 107 mortality studies, 150, 154, 171 Animal odors, 107 Chicago mortality studies, 150 Diurnal variation Aromatic hydrocarbons as carcino- Children particulate, 40, 41 gens, 137-141 Dublin, Ireland Asbestos morbidity studies, 165-167 Chlorides mortality study, 154, 155 toxicity of, 129-130, 150 corrosive effects, 71 Dust Automobile exhaust emissions, 26 corrosive effects, 65-74 Automobiles Clearance model respiratory system, 120-121 effects on resp. tract, 112-119 corrosion of, 71 Clearance of particulate matter in effect on textiles, 71-72, 74 the respiratory system, 121-123 Dust components, 92-93 Dust mineral B Climate effects of particulate on, 35, 42- deposition, 117 Beryllium 44 Dustfall toxicity of, 129-130, 150 Climatic change description of, 11, 16-17 Birmingham, Alabama world-wide, 42-44 seasonal variation, 39 public opinion survey, 101 Coal combustion typical urban values, 17 Bronchitis effects of smoke on animals, 131- Dustfall collectors, 17-19 morbidity studies of, 156, 161- 132 Dustfall jars, 17 169 emission from, 24, 27 mortality studies of, 150-154, Coal combustion gases Economic effects, 79-85 156-161 corrosive effects, 69-70 Economical level Brownian motion, 9, 113 Coal dust relationship to mortality, 156- Buffalo, New York deposition, 117 158, 159-162, 163, 164, 167, mortality studies, 158, 160, 161, physiological effects of, 133 170, 176 170, 171 Combustible waste odors, 107 Electrical instruments public opinion survey, 101 Combustion odors, 107 corrosion of, 69 Building materials Combustion products Electron microscopy, 20, 23 deterioration of, 69 corrosive effects, 69-70 Elutriators, 17 Buildings Computer techniques of sampling, Emission factors, 24 deterioration, 78-74 19 Emission inventories, 12 208 England I Long term, 156-161 morbidity studies, 154-156, 161, Illumination Motor vehicles 162, 163, 164-169, 171-176 seasonal variation, 37 emissions from, 26 mortality studies, 150-153, 154,Industrial odors, 107 Municipal incineration 156-159, 171-176 International Standard Calibration emissions from, 24-25 Epidemiological studies, 150-154 Curve for refiectometers, 21 Exacerbation of chronic diseases, Irkutsk (U.S.S.R.) N 148-149, 154-156, 161-176 morbidity studies, 167, 174 Extinction Iron Nasal fractionation, 118 dependence on particle size, 55 corrosion of, 65-69 Nashville, Tennessee Iron dust morbidity studies, 164, 173 F effect on textiles, 72 mortality studies, 160, 161, 173 Iron oxide public opinion survey, 100-101 Ferric sulfate effects on vegetation, 94 Nephelometer, 19 toxicity, 132 -133 Italy NewHampshire (Berlin) Filters morbidity studies, 162, 167, 173, Morbidity study, 164, 173 sampling, 20-22 174 New York City Fluorides morbidity studies, 154-156, 165, effects on vegetation, 93-94 J 170, 171, 173, 176 Fluorosis Japan mortality studies, 156, 170-171 animal, 95 morbidity study, 162, 167, 173, Nickel Fog 174-175 corrosion of, 67-69 correlation with mortality, 150- mortality study, 154, 171 Nitrogen dioxide 163 toxicity, 135 Food odors, 107 L Nucleation properties, 8-9 Formaldehyde Leaves Nuisance surveys, 99-102 toxicity, 122, 135, 136 dust effects on, 89-96 Foundry Light absorption, 52-53 odors from, 107 Light scattering, 9-10, 37-38, 52- Foundry dust 63, 54-58 effects on vegetation, 94 Linen France soiling and deterioration of, 71- Odors economic effects of air pollution 74 association with particles, 106- in, 81 London 107 Fuel oil combustion morbidity studies, 154-156, 162, emission sources, 107 emissions from, 24 163, 165-167, 168-169, 172, 173, Open hearth furnaces 174, 175 emissions from, 24 Optical density, 20-22 G mortality studies, 56-158, 171- 172 Optical properties, 9-10 Lung deposition, 118-119 Osaka Gas and particulate mixtures mortality study, 154, 171 synergistic pulmonary effects, Lung dynamics 134-137 model of, 114-116 Gases toxicity of, 134-137 M Great Britain economic effects of air pollution Magnesium oxide Paint odors, 107 in, 81 effects on vegetation, 94 Painted surfaces deterioration of, 71, 72-74 medical effects of air pollution, Membrane filters, 20 150-159, 161-169, 171-176 Messthelioma, 129-130 Particle formation mechanisms, 10- Metals (see specific metal) 11 Meuse Valley Particle-gas reactions, 10 H mortality studies, 150 Particle size Haze Mie solutions, 54-55 role in measuring techniques, 149 particulate size distribution of;Morbidity role in pulmonary deposition, 52-53 correlation with pollution, 148- 114, 118-119 High-volume sampler, 22-23 149, 154-156, 161-176 role in pulmonary effects, 182 - Hydration process in children, 165-167 133 dust crust, 91-92 incapacity for work; 164-165 distribution, 58, 117 Hydrocarbons as carcinogens, 138-Mortality Pennsylvania communities 141 correlation with acute air pollu- morbidity study, 167-168, 175 Hygroscopic particles tion episodes, 148, 150-154 Philadelphia, Pennsylvania effect on pulmonary irritants, exposures to air pollution, 148, economic effects of air pollution 136 150-154, 156-161, 169-176 in, 83

209 Photochemical reaction model, 10 Smoke Textiles Photometry, 20 corrosive effects, 72-74 soiling and deterioration of, 71- Photomicrographic atlas, 19 toxicity of, 160-164 74 Physiological response, 132-134 Smoke plumes Toxicity Pittsburgh, Pennsylvania optical properties of, 53 adsorbed substances, 130 economicsurvey ofpollution Smoke shade intrinsic of particulates, 129-130 damage, 180 correlation with mortality, 154 reduction of, 130-131 Plants Smoking Transmissivity dust effects on, 89-93 cigarette, 137, 141, 149-160, 168, variation with climate, 36 Pneumocoiosis, 122, 131 161, 162, 163, 166 Transmittance, 20-21 Pneumonia Sodium chloride Trees mortality, 157 corrosive effects, 71 (lust effects on, 90-92 Poly-nuclear aromatic hydrocarbonsSolar radiation Triphenyl phosphate carcinogenicity of, 137 effects of particulates on, 35-38 deposition, 117 Post office employees physical factors effecting, 38-39 Turbidimetry, 19 morbidity studies, 163 seasonal variations, 39-40 Turbidity, 37 Precipitation weekly variations, 39 influence of particulates on, 40- Soot, 42 corrosive effects, 65-74 U Public opinion surveys, 99-102 effects on textiles, 71-74 Pulmonary flow resistance, 132- effects on vegetation, 89-94 Upper Ohio River Valley 1, Sorption properties, 8 economic survey of pollution Pulmonary function St. Louis, Missouri damage, 81, 82 alterations in, 132-134 economic effects of pollution in, 83 R public opinion survey, 99-100 V Race Steel relationship to mortality, 156 corrosion of, 65-69, 72-74 Varnished surfaces Rainfall (See Precipitation) Stokes law, 5-6 deterioration of, 69-71, 72-74 Refinery Sulfur dioxide Vegetables odors from, 107 corrosive effects, 65 dust effects'on, 89-96 Reflectance, 21 odor, 107 Visibility, 51-61 Reflectometer, 21 toxicity of, 130-131, 132, 136-137 effect of fog upon, 53-54 Respiratory illness Sulfuric acid effects of natural aerosols on, 63 relation to smoke level, 148, 162- effects on vegetation, 94 effects of particulates on, 36-38, 167 Sulfuric acid manufacturing 53-53 Respiratory system emissions from, 24 Volatile particles, 106 models of, 114-116 Supersaturation Respiratory tract nuclei, 23 anatomy of, 111-112 Surface coatings W Retention deterioration of, 69-71, 72-74 human vs.animal respiratory Surface properties, 8-9 Washington, D.C. (Suburban) system, 119 Surveys of damage, 79-84 economic effects of air pollution, respiratory system, 112-119 Suspended particulate /. 83 Rotterdam means for urban areas, 11, 13-16Waste decomposition morbidity study, 168, 175 Synergistic effects odors from, 107 Rusting, 65-69, 72-74 gases and particulate, 135 Synthetic textiles Wool S soiling and deterioration of; 71- soiling and deterioration of, 71- 74 Salford, England 74 morbidity studies, 164 Syracuse, New York mortality studies, 158-159 economic effects of air pollution X Sampling methods; 17-23 in, 83 X -ray diffraction, 19 Scattering coefficient, '55-58 Settling velocities, 16 Sewage odOrs from, 107 Zinc Sex Tape samplers, 20-22 corrosion of, 66, 67-68; 72-74 relationship to mortality, 156 Telephone workmen Zinc dust Sheffield, England.'. morbidity studies, 162, 163 effect on textiles, 72 morbidity studies, 167, 168; 170, irettshydro naphthalene Zinc salts 174 toxicity, 131 corrosive effects, 71

210 '217 et"

ACKNOWLEDGEMENTS

The following sources, in most instances Figure 1-1.Academic Press, Inc., New the copyright holders, have granted permis- York, N. Y. sion to the National Air Pollution Control Figures 1-3, 2-2, 3-1, 3-4, 3-5, 3-6, 9-4, 9-5, Administration to include the following fig- 9-6, 9-7.Pergamon PressInc.,New ures and tables in the Air Quality Criteria: York, N. Y. Table 1-1.Los Angeles data courtesy of Los Figure 1-4.American Industrial Hygiene Angeles County Air Pollution Control Dis- Association, Detroit, Mich. trict Figures 2-1, 3-7, 7-2.Air Pollution Control Table p. 26. Chemical. Processing Engineer- Association, Pittsburgh, Pa. ing, London Figures 2-3, 2-4, 11-2.Controller, Her Maj- esty's Stationary Office, London, England Table p. 27.American Society of Mechani- cal Engineers, New York, N. Y. Figures 2-5, 3-1, 3-3.American Meteoro- logical Society, Boston, Mass. Table 2-2.The Gray Printing Company, DuBois, Pennsylvania Figure 3-8.American Chemical Society, Washington, D. C. Tables 3-1, 8-1.Air Pollution Control As- sociation, Pittsburgh, Pa. Figure 4-1.Iron and Steel Institute, Lon- don, England Table 3-2.Reinhold Book Corporation, New York, N. Y. Figure 4-2.American Society for Testing & Materials, Philadelphia, Pa. Table 4-1.Iron and Steel Institute, London Figure 4-3.District of Columbia Health Tables 4-2, 4-3.American Society for Test- Department, Washington, D. C. ing & Materials, Philadelphia, Pa. Figure 5-1.Environmental Health & Safety Table 5-1.Mellon Institute, Pittsburgh, Pa. Research Associates, New Roc , New York Table 10-2.American Industrial Hygiene Association, Detroit, Mich. Figures 6-1, 6-2, 6-3.Ellis F. Darley, Uni- versity of California, Riverside, Calif. Tables 10-3, 10-4, 11-2, 11-3, 11-4.Ameri- can Medical Association, Chicago, Ill. Figure. 11-1.Royal Society of Health, Lori don, England Table 10-5.American Association for the Advancement of Science, Washington, D.C. Figure 11-3.Royal Dublin Society, Dublin, Ireland Table 10-6.National Tuberculosis & Res- piratory Disease Association, New York, Figure 11-7.American Medical Associa- N.Y. tion, Chicago, Ill. Table 11-1.Pergamon Press, Inc., New Figure 11-8.British Medical Journal, Lon- York, N. Y. don, England

* U. 8. GOVERNMENT PRINTING OFFICE : 1969-347411/32 211