operation the chain of infection from rat to called for, i.e., the definition of " receptive rat, from rat to man, and from man to man. areas " as those where R. rattus exists side by There should be no vaccination, which is side with a sufficiently numerous and vulner­ too slow and unreliable for immediate pro­ able field rodent fauna; of "critical areas" as phylaxis, but chemoprophylaxis by means of inveterate wild foci together with the ports, sulfonamides. There should be no cordon even if free from infection, situated in their sanitaire or isolation measures, since these neighbourhood; and, finally, of "immune are rendered pointless by disinsecting, chemo­ areas" as areas free from R. rattus, together prophylaxis of contacts, and treatment of with the neighbouring ports. These defini­ patients with sulfonamides or antibiotics. tions might permit the immediate preparation As regards long-term prophylaxis in in­ of agreements for international assistance in fected territory, once it had been demon­ the event of the invasion of a" receptive area" strated that wild or field rodents alone play a by plague. In this way the threatened country part in the maintenance and propagation of could be provided with everything necessary the infection, it seemed logical to carry out to ensure the rapid eradication of the disease eradi.cation campaigns based on the destruc­ before it had time to take root and spread. tion or at least disinse;tion of field rodents and An international programme for the detec­ their burrows. Because of certain prejudices tion and delimitation of " critical areas " arising from previous failures, public health should be drawn up, making it possible to authorities were at first reluctant to under­ designate " infective p::>rts " and to plan the take such campaigns, but the success of eradication of plague in the areas con:::.::rnd. those carried out in certain inveterate foci In the third report of the WHO Expert Com­ in the USSR showed that they were the only mittee on Plague,5 a programme of this type means pf .obtaining lasting results. headed the Committee's " Recommenda­ Where long-term prophylaxis at the inter­ tions for co-ordinated research ". national level is concerned, certain definitions (as in the case of yellow fever) appear to be ' Wld Hlth Or5. techn. Rep. Szr., !9SJ, 165

AIR POLLUTION

In December 1952 many parts of the women, and most of the sick were over 45 British Isles were covered by an anticyclone. years of age. There were appreciably more It was cold, and fog was widespread, parti­ hospital admissions than usual, particularly cularly in and around London, which re­ for cases of acute respiratory infection but mained blanketed in it for five days. Within also for heart disease. The mortality records about 12 hours from the beginning of the fog showed that, during the week of the fog and the morbidity rate in the Greater London the week after, there were 4000 deaths more area became very much higher than usual than the average. Most of the people who for the time of the year. The common form died were recorded as having had chronic of illness experienced was characterized by a bronchitis, bronchopneumonia, other lung relatively unproductive cough, nasal dis­ disease, or disease of the heart. charge, sore throat, and sudden attacks of During the fog the smoke concentration vomiting, and was especially severe in per­ was found to be five times greater than at sons who had had a previous history of other times ; the sulfur dioxide concentration chest trouble. In the very ill, dyspnoea, about six times greater. A Committee on cyanosis, moderate fever, and riiles and Air Pollution set up in 1953 by the Govern­ rhonchi indicative of bronchospasm and the ment of Great Britain " to examine the presence of bronchial secretions were nature, causes and effects of air pollution and present. Men were affected more than the efficacy of present preventive measures "

426 held that, while the evidence did not provide by waste materials, and ground water con­ a clear indictment of any one constituent of taminated-and, as a corollary, they have the fog, the conclusion was inescapalb that been breeding-grounds for vermin and bac­ the excessive mortality and increased inci­ teria and centres of epidemics. The dangers dence of respiratory infection during and of impure water and the indiscriminate dis­ immediately after the fog were the result of posal of sewage and refuse have slowly been irritation of the respiratory tract by contami­ recognized, however, and it is safe to say th~t nants of the fog-the irritants mainly practically all towns of reasonable size in the responsible probably being derived from the world pay at least lip service to the ideals of combustion of coal and its products and their pure water and sanitary disposal of sewage lethal effects being almost wholly exercised and refuse. on persons suffering from chronic respiratory Only relatively recently has so much atten­ or cardiovascular disorders. tion been paid to pollution of the air. The This was not the first time that air pollution biological processes of living matter, certain has been blamed for producing ill effects on natural phenomena and many of man's health in London. The English Parliament activities-especially since the Industrial had passed an act as lor g ago as 1273 for­ Revolution-result in the liberation of gases, bidding the burning of coal in London, and vapours, dust, and aerosols of suspended in 1306 a man was executed for doing so. particles into the air, and some of these The law quickly fell into abeyance as the atmospheric contaminants are harmful to shortage of wood as fuel became more health. The study of the nature, properties, pronounced, and when the Industrial Revolu­ and behaviour of the contaminants is tion came attempts to prevent the pollution difficult, and requires the co-operation of of the atmosphere were unavailing. Towards physicists, chemists, and biologists; the the end of the nineteenth century big in­ polluting gases and vapours may form a creases in mortality occurred in association proportion of only a few parts per million with periods of severe fog in 1873, 1880, 1882, or even one part per thousand million or less, 1891 and 1892. but the toxicity of some compounds in the Air pollution and its evil effects were not, parts per thousand million range may be and are not, confined to England, the home greater than that of others in the parts per of the Industrial Revolution. There was a thousand range. Some of the contaminants notorious occurrence in 1930 in the Meuse have not been identifed, and it will be years valley in Belgium, asscciated with anti­ before full inforrr ation becomes available on cyclonic conditions, cold, fcg, and heavy many aspects of air pollution, so complex is industry. In 1948 the industrial town of the subject, so rr:any and changing the factors Donora, USA, some 30 miles south of involved. Vv hereas the industrial hygienist Pittsburg, was afflicted by a heavy fog from works in a semi-closed atmcsphere where 27 to 31 October; 5910 persons (42.7% of concentrations are higher than in the street, the population) fell ill, 15.5% mildly, 16.8% and conditions are somewhat simpler, so moderately, and 10.4% severely; 17 persons that sarr:pling processes lasting only a few died. There was also the Poza Rica incident minutes are usually suff.cient to give him a of 1950 in Mexico. Mention should be made, picture of what is taking place in the factory, too, of the recurrent " smcg" of Los sampling processes in the open air must usu­ Angeles, occurring during the summer and ally continue for months and often for years early autumn and causing irritation of the before the factors involved in air pollution eyes, nose and throat, damaging vegetation, are understood. Thus the forms of pollution and making the atmosphere hazy. encountered in Los Angeles since 1945 are Wherever men collect they tend to pollute still not well understood, although measure­ their environment. Throughout human ments have been proceeding for over ten years. history towns have been concentrations of Nevertheless, an appreciable amount of refuse and dust, with rivers and wells polluted knowledge exists about air pollution and its

427 effects on human health. This knowledge is so it became necessary for states and muni­ summed up in a WHO monograph that has cipalities to pass laws to make it compulsory just been published.1 In this volume, which for householders and industries to burn is the work of an international group of smokeless fuels or to use more efficient experts, a historical review of atmospheric equipment to burn fuel. In Great Britain pollution is followed by sections on sampling there was no natural gas; oil had to be paid and analysis of the contaminants, the instru­ for in foreign currency; and even if industries ments used, the physical and chemical nature could be compelled to install more efficient of air pollution, the role of meteorology, the machinery for getting rid of smoke the main effects of air pollution on human health, problem would be to prevent the domestic animals, and plants, the economic and social consumer of coal from continuing to burn aspects of air pollution, the control of pollu­ it wastefully in open grates. A considerable tion by site selection and zoning and by proportion of the air pollution of the great process changes or equipment, fuel selection fog of 1952 in London was attributable to and utilization, air pollution legislation, smoke from fires burning in innumerable standards, and enforcement, and finally-and open grates throughout the metropolis. topically-radioactive pollution of the atmo­ Smoke is not by any means the only sphere. atmospheric pollutant. Grit and dust, sulfur By the end of the nineteenth century dioxide from coal and smelters, hydro­ practically everything that is now known chloric acid from such processes as the pro­ about the causes of smoke-the visible cloud duction of sodium carbonate from common of suspended carbon particles that is the first salt, hydrogen sulfide from tar distillation, and most obvious of the pollutants of the air nitrogen dioxide from the chamber process -and its elimination had already been said for sulfuric acid, hydrogen fluoride from the in Great Britain. But smoke was not elimi­ production of superphosphate and alumi­ nated because it is a by-product of activities nium, lead, arsenic, zinc and copper deriva­ producing goods and profits and thus com­ tives from the metallurgical· industries, manding the attention and support of finely divided beryllium from the manu­ financial interests. Moreover, the damage facture of radio valves, hydrocarbons, alde­ done by smoke, though considerable, was not hydes, and olefines from combustion of oil, very clearly visible to the individual smoke carbon monoxide from a variety of sources, producer because widely spread, and since all enter the air to join the sulfur dioxide, the damage was due to a large number of hydrogen fluoride and hydrogen derived small producers a clear relationship between from volcanic disturbances, the hydrogen cause and effect was not easy to establish; sulfide from seepage of natural gas, volcanoes nor, for the same reasons, could the blame or action of sulfide bacteria, the ozone formed readily be pinned upon definite persons who photochemically or by electric discharge, could be asked to remedy the situation. In the dust and aerosols consisting of salt American cities a few decades later it was particles from sea water, particles from soil found that even when public opinion was and vegetation, dust of meteoric origin, convinced of the need for smoke reduction bacteria spores and pollen. The concentra­ there was reluctance to take the necessary tion of the substances not contributed by measures, the attitude always being that the man is extremely low, except in the immediate responsibility for doing so was someone vicinity of natural sources, but the concentra­ else's. Circumstances have helped some tion of those contributed by man can, countries in the campaign to abate the smoke meteorological conditions aiding or in the nuisance : in the USA supplies of oil and industrial centres themselves, be high enough natural gas, which burn with little or no to be injurious to health, and has been the smoke, became more freely available. Even subject of much industrial legislation. This legislation has on the whole been concerned t Air pollution (World Health Organization Monograph Series, No. 46), 1960, Geneva with conditions in the factory or workshop

428 itself, not to any great extent with conditions and very fine particles, generally classified as outside. "inert", may cause bronchoconstriction, The complete list of atmospheric contamin­ apparently by virtue of an unexplained local ants that are harmful to the health is not irritant action. The lining of the bronchi may known. In Los Angeles it was at first thought suffer from interference with its cleansing that sulfur dioxide was the main irritant in the system, and the secretory rhythm of the smog, but now the list of substances currently mucous glands may be impaired; or there may considered to be causally related includes as be severe inflammatory response in the well oxides of nitrogen, aldehydes, ketones, mucosa, with desquamation of the surface acids, chlorinated hydrocarbons, acroleins (or epithelium. Hypersensitivity and hyperirrita­ an " acrolein-like substance "), chlorinated bility may occur. The reports on acute air aldehydes and related substances, formyl pollution episodes indicate that the damage compounds, ozonides and peroxides of hydro­ was due to local action of the pollutants on carbons of the series present in gasoline the exposed membranes, and that, when the (especially the straight-chain hydrocarbons respiratory tract was affected in some sus­ containing double bonds), ozone, nitro­ ceptible persons, secondary adverse effects on olefines, peracylnitrites, organic free radicals, the heart became manifest. The short-term and carbon suboxide. This is a formidable effects of an increased concentration of list, but it is not exhaustive. It is considered atmospheric contaminants on persons suffer­ that the gases and aerosols discharged into the ing from previous disease of the lungs or air may not be irritant in themselves but may heart have been shown in the London and be acted upon by the ultraviolet rays of the Don ora episodes; what the long-term effects sunlight and the resulting syntheses may be of these contaminants in lower concentrations the smog-forming substance or substances. may be both on those with previous disease The present view is that the oxides of nitrogen and those without still remains to be elucid­ and hydrocarbons (mostly olefines), both ated. Among the possible effects is the arising from corn bustion processes, especially stimulation of cancer. of petroleum products, are involved in the Nor does air pollution affect only human photochemical changes that take place, with health. The economic and social effects are appreciable increase of the amount of ozone, considerable. Livestock and plants suffer; in the air. In other words, more important materials and their protective coverings than the combustion of coal and allied corrode; houses and other buildings need in­ products-which were the main cause of the creased maintenance, inside and outside; London fog of 1952-is the combustion of chimneys, and motors and other engines carry gasoline by the well over 2 million motor cars an unburnt residue; technical measures are in Los Angeles, with their consumption of required to suppress or reduce the smoke or over 5 million gallons of gasoline daily. emissions from factories; the removal of dust A great deal remains to be found out about and the treatment of smoke mean increased the effect of atmospheric contaminants on the use of electric power; transport costs go up human body. The biochemical reactions they in times of smog or fog; more electricity is produce vary: they may corrode, like sulfuric used for lighting; pollution control requires acid; or react with cellular proteins, like the the organization of a service to carry it out; aldehydes. They may be strong oxidizing research into the many complex problems of agents, like ozone, or interfere with enzyme pollution cannot be done without funds. The systems within the cell. They may, like the social consequences are not easy to assess. nitro-olefines, affect the eyes and the lungs. In the United Kingdom, however, they may They may act on the upper part of the res­ be seen in the drift of the population from the piratory tract, or aerosols may aid the irritants grimy, smoke-blackened towns of the North to gain access to the lower part. Irritation of of England to the relatively less polluted the upper part may cause reflex spasm of the South, with the vast effects on the community distant bronchioles and severe symptoms, that this may have.

429 It must not be assumed that air pollution is failed to use their powers to make by-laws. As confined to the industrial nations of Europe a result of the London smog of 1952, however, and North America, for industry is spreading a Committee on Air Pollution was set up, 4 and throughout the world, carrying pollution in a Clean Air Act was passed in 1956 that in­ its wake. In Mexico City, 2 for example, the corporated many of its recommendations. average visibility up to 1940 over the city was Under this act it is an offence to emit dark between 10 and 20 km; now it is hardly more smoke from a chimney for longer periods that than 4. During fine weather about 5 tons of may be specified by the Minister of Housing dust and grit are deposited per square kilo­ and Local Government; no furnaces other metre per week over the city (15 in the centre). than small ones for mainly domestic purposes Many tropical cities enjoy a climate of warm may be installed, unless they can be operated, sunshine and gentle breezes; but this is a as far as practicable, continuously without positive disadvantage as far as air pollution is emitting smoke; apparatus may be required concerned, because they are not, like so to be provided to record the density or dark­ many industrial towns of more temperate ness of the smoke; and smoke control areas zones, washed and ventilated by rain and may be created. Other provisions cover the wind. height of chimneys, mine refuse, road traffic, Attempts to remedy air pollution date back smoke from railway engines and ships, grit in some countries to many years ago, but, as and dust, pollutants from chemical and one contributor to the WHO monograph other processes, and electricity generating says: 3 stations. In the USA there is no general legislation " With few exceptions air pollution control legisla­ on air pollution, only state or local regula­ tion in the various countries is inadequate. A frequent tions; but almost every city now has some form disadvantage is that the first control measures were of regulation, and it is often more stringent introduced many years ago, and the legislation at present in force takes no account of the enormous than the law in the United Kingdom, restrict­ growth of industry, new types of air contaminant, and ing the type and quality of the coals used in new sources of pollution, such as motor vehicles and hand-fired furnaces and domestic heating heating installations. Some laws provide solely for appliances, the density of the smoke emitted, the payment of compensation for damage caused by or the amount of grit and dust allowable. air pollution." The result has been an astonishing improve­ ment of the air in some cities, as for example In the United Kingdom a Public Health in Pittsburgh. Act of 1936 constituted as statutory nuisances In most other countries legislation is out­ any industrial installation for the combustion of-date and inadequate to deal with the of fuel that did not, as far as practicable, pre­ situation: vent the emission of smoke, and any chimney (except a chimney of a private house) emitting smoke in such a quantity as to be a nuisance. "In the present state of knowledge, complete elimination of pollution is not practicable, but there A local authority could serve notice on the could be much greater improvement than has so far offender requiring him to abate the nuisance, been achieved. Such improvement will only be ob­ and if the notice were not complied with he tained by better legislation more effectively adminis­ could be brought before a court, fined, and tered, increasing knowledge based on intensified ordered to comply. Local authorities could research and development work, and a more de­ also make by-laws regulating the emission of termined public opinion. As new industrial processes smoke. Unfortunately, the local authorities are developed and conditions changed, modifications often did not take action against offenders and in legislation and methods of enf<;>rcement will be required from time to time; but it must be recognized that no one set of preventive measures will meet all ' UNESCO Courier, 1959, 3, 15 ' Parker, A. (1960) Air pollution legislation standards and enforcement. In: Air pollution, p. 365 'See page 426.

430 needs everywhere owing to differences in the condi­ The public health worker should be aware tions in various countries and localities." 5 of the problem that air pollution represents. To give some figures for one of the countries The study of the problem of air pollution where pollution is most serious: in the United has received a new impetus from the arrival of Kingdom over a million tons of smoke are nuclear energy on the world scene, and the emitted yearly from domestic fires; half a great expansion in the use of radioactive million from industry; and 100 000 from the materials. The dangers of radioactivity are railways. Out of 900 000 tons of grit and dust well known because of the mishaps that have liberated into the air domestic chimneys occurred over the relatively long period in emit 100 000. Sulfur dioxide emitted amounts which X-rays and radium have been used; to 5.5 million tons (the domestic fires emitting but these dangers have been confined to the nearly a million of this). 6 These figures give laboratory and as much as possible mitigated. some idea of the extent of the problem in some The release of radioactive waste into the countries and the uphill task involved in atmosphere, with its possible effects both on restoring some measure of purity to the air. the living and the unborn, has stimulated It is a task that will need intensive research, inquiry into the radioactivity of the air, the collection and dissemination of knowledge factors involved in its differing concentra­ already acquired and to be acquired in the tions, the fate of radioactive contaminants, future, the creation of a special administra­ radiobiology and radiotoxicology, methods of tion, the passing of appropriate legislation, measuring maximum permissible levels, and and the training of officials in the methods of ways of prevention. This inquiry must result control. Above all, it will need the backing of in advances in knowledge of the other con­ public opinion. This can only be obtained by taminants of the air, and it may be that systematic education of the public, by in­ concern about the consequences of radio­ culcating the feeling that any emission of active pollution will lead to greater con­ pollutants into the atmosphere is an offence cern about the other forms of pollution as that cannot be countenanced, whether the well. offender is industry or the private individual.

5 Parker, A. (1960) Air pollution legislation · standards and • National Society for Clean Air (1960) Clean air year book for enforcement. In: Air pollution, p. 380 1960, London (Quoted in Nature, 1960, 187, 200)

The Holy See supports malaria ertdication

The Holy See has made a second symbolic contribution of $1000 to the WHO Malaria Eradication Special Account. On behalf of His Holiness Pope John XXIII, a cheque for this sum has been presented to Dr M. G. Candau, Director-General of WHO, by the Reveren_d Father Henri de Riedmatten, 0. P., Ecclesiastical Adviser of the International Catholic Organizations' Information Centre, Geneva. In presenting the cheque, the Reverend Father de Riedmatten stated that it represents not merely a sign of approval of the malaria eradica­ tion campaign, but also an appeal to the generosity of Christians everywhere in favour of this campaign.

431