Health Risk and Exposure Assessment for Ozone Final Report
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Health Risk and Exposure Assessment for Ozone Final Report This page left intentionally blank EPA-452/R-14-004a August 2014 Health Risk and Exposure Assessment for Ozone Final Report U.S. Environmental Protection Agency Office of Air and Radiation Office of Air Quality Planning and Standards Health and Environmental Impacts Division Risk and Benefits Group Research Triangle Park, North Carolina 27711 DISCLAIMER This final document has been prepared by staff from the Risk and Benefits Group, Health and Environmental Impacts Division, Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency. Any findings and conclusions are those of the authors and do not necessarily reflect the views of the Agency. Questions related to this document should be addressed to Dr. Bryan Hubbell, U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, C539-07, Research Triangle Park, North Carolina 27711 (email: [email protected]). TABLE OF CONTENTS TABLE OF CONTENTS .............................................................................................................. i LIST OF FIGURES .................................................................................................................... vii LIST OF TABLES .................................................................................................................... xvii LIST OF ACRONYMS/ABBREVIATIONS ......................................................................... xxiii 1 INTRODUCTION.......................................................................................................... 1-1 1.1 HISTORY .................................................................................................................. 1-3 1.2 CURRENT RISK AND EXPOSURE ASSESSMENT: GOALS AND PLANNED APPROACH .............................................................................................................. 1-6 1.3 ORGANIZATION OF DOCUMENT ....................................................................... 1-7 1.4 REFERENCES .......................................................................................................... 1-8 2 OVERVIEW OF EXPOSURE AND RISK ASSESSMENT DESIGN ..................... 2-1 2.1 POLICY-RELEVANT EXPOSURE AND RISK QUESTIONS .............................. 2-2 2.2 AIR QUALITY CHARACTERIZATION ................................................................ 2-4 2.2.1 Ozone Chemistry and Response to Changes in Precursor Emissions .................. 2-5 2.2.2 Sources of Ozone and Ozone Precursors ............................................................. 2-6 2.2.3 Simulation of Just Meeting the Existing and Alternative Standards ................... 2-7 2.3 CONSIDERATION OF HEALTH EVIDENCE ....................................................... 2-8 2.3.1 Exposures of Concern .......................................................................................... 2-9 2.3.2 Health Risk Endpoints ....................................................................................... 2-10 2.3.3 Exposure and Concentration-Response Functions for Health Risk Endpoints .. 2-13 2.3.4 At-Risk Populations ........................................................................................... 2-15 2.4 URBAN-SCALE MODELING OF INDIVIDUAL EXPOSURE ........................... 2-16 2.4.1 Microenvironmental Ozone Concentrations ...................................................... 2-17 2.4.2 Human Activity Patterns .................................................................................... 2-18 2.4.3 Modeling of Exposures Associated with Simulating Just Meeting Ozone Standards ............................................................................................................ 2-19 2.4.4 Considerations in Selecting Urban Study Areas for the Exposure Analysis ..... 2-20 2.5 URBAN- AND NATIONAL-SCALE RISK ASSESSMENT ................................ 2-20 2.5.1 Attributable Risk ................................................................................................ 2-21 2.5.2 Modeling of Health Risk Associated with Total Ozone Exposure .................... 2-22 2.5.3 Distributions of Risk Across Ozone Concentrations ......................................... 2-23 i 2.5.4 Modeling Risk Associated with Simulating Just Meeting Ozone Standards ..... 2-23 2.5.5 Considerations in Selecting Urban Study Areas for the Risk Assessment ........ 2-24 2.6 RISK CHARACTERIZATION ............................................................................... 2-24 2.7 REFERENCES ........................................................................................................ 2-26 3 SCOPE ............................................................................................................................ 3-1 3.1 OVERVIEW OF THE EXPOSURE AND RISK ASSESSMENTS FROM THE LAST REVIEW ......................................................................................................... 3-2 3.1.1 Overview of Exposure Assessment from the Last Review .................................. 3-2 3.1.2 Overview of Risk Assessment from the Last Review ......................................... 3-3 3.2 PLAN FOR THE CURRENT EXPOSURE AND RISK ASSESSMENTS .............. 3-5 3.3 CHARACTTERIZATION OF UNCERTAINTY AND VARIABILITY IN THE CONTEXT OF THE OZONE EXPOSURE AND RISK ASSESSMENT ............... 3-7 3.4 CHARACTERIZATION OF AIR QUALITY ........................................................ 3-10 3.5 CHARACTERIZATION OF URBAN-SCALE HUMAN EXPOSURE ................ 3-13 3.6 CHARACTERIZATION OF URBAN-SCALE HEALTH RISKS BASED ON CONTROLLED HUMAN EXPOSURE STUDIES ................................................ 3-15 3.7 CHARACTERIZATION OF URBAN-SCALE HEALTH RISK BASED ON EPIDEMIOLOGICAL STUDIES ........................................................................... 3-18 3.8 NATIONAL-SCALE MORTALITY RISK ASSESSMENT .................................. 3-21 3.9 PRESENTATION OF EXPOSURE AND RISK ESTIMATES TO INFORM THE OZONE NAAQS POLICY ASSESSMENT ........................................................... 3-24 3.10 REFERENCES ........................................................................................................ 3-26 4 AIR QUALITY CHARACTERIZATION .................................................................. 4-1 4.1 INTRODUCTION ..................................................................................................... 4-1 4.2 OVERVIEW OF OZONE MONITORING AND AIR QUALITY DATA .............. 4-1 4.3 OVERVIEW OF URBAN-SCALE AIR QUALITY INPUTS TO RISK AND EXPOSURE ASSESSMENTS .................................................................................. 4-4 4.3.1 Urban Study Areas ............................................................................................... 4-5 4.3.2 Recent Air Quality ............................................................................................... 4-8 4.3.3 Air Quality Adjustments for Just Meeting Existing and Potential Alternative Ozone Standards ................................................................................................ 4-13 4.4 OVERVIEW OF NATIONAL-SCALE AIR QUALITY INPUTS ......................... 4-30 4.5 UNCERTAINITIES IN MODELING OF RESPONSES TO EMISSION REDUCTIONS TO JUST MEET EXISTING AND POTENTIAL ALTERNATIVE STANDARDS.......................................................................................................... 4-37 4.6 REFERENCES ........................................................................................................ 4-47 5 CHARACTERIZATION OF URBAN-SCALE HUMAN EXPOSURE ................... 5-1 5.1 SYNOPSIS OF OZONE EXPOSURE AND EXPOSURE MODELING ................. 5-2 5.1.1 Human Exposure .................................................................................................. 5-2 ii 5.1.2 Estimating Ozone Exposure ................................................................................. 5-3 5.1.3 Modeling Ozone Exposure Using APEX ............................................................ 5-4 5.2 SCOPE OF THE EXPOSURE ASSESSMENT ........................................................ 5-7 5.2.1 Urban Areas Selected ........................................................................................... 5-7 5.2.2 Time Periods Simulated ....................................................................................... 5-9 5.2.3 Ambient Concentrations Used ............................................................................. 5-9 5.2.4 Meteorological Data Used ................................................................................. 5-11 5.2.5 Populations Simulated ....................................................................................... 5-11 5.2.6 Key Physiological Processes and Personal Attributes Modeled ........................ 5-15 5.2.7 Microenvironments Modeled ............................................................................. 5-17 5.2.8 Model Output ..................................................................................................... 5-18 5.3 EXPOSURE ASSESSMENT RESULTS ................................................................ 5-24 5.3.1 Overview ............................................................................................................ 5-24 5.3.2 Exposure Modeling Results for Base Air Quality ............................................. 5-24 5.3.3 Exposure Modeling Results for Simulations of Just Meeting the Existing and Alternative 8-hour