Air pollution has occasionally reached acutely lethal proportions. Outstanding among the recorded instances when contamination of the air was the immediate cause of illness and death are the Meuse Valley (Belgium) case, where one hundred persons were made ill and sixty-three died in 1930; the Donora (Pennsylvania) episode of 1948 when over a thousand persons were severely affected and twenty died; and the London case of 1952, when an estimated four thousand excess deaths were recorded during a two-week period December. However, the occasional instances of deathly gases enveloping a city do not begin to define the magnitude of the problem. The greatest health problems and the greatest property damage appear to arise from persistent exposure at a great many scattered locations.
One survey has indicated that air pollution to one degree or another affects 10,000 American communities. It ranges from highly localized effects—perhaps the smokes and gases of a single factory chimney—that blanket entire metropolitan areas (Los Angeles is the obvious example). The damage to livestock, vegetation, and materials alone has been roughly estimated at $3 to $4 billion annually, and yearly expenditures for abatement at about $300 million. In recent years the character of air pollution has undergone radical change which is why it is not possible at present to formulate a meaningful index of its magnitude.
The substances found in polluted air are often divided into two categories: stable primary substances that are not changed in the air and, consequently, comparatively easily traced to their source. These arise from industrial, commercial, domestic, transport, and agricultural activities and are in the form of dusts, smokes, fumes and droplets. The range of types of these pollutants is extremely wide. They obscure sunlight and visibility, dirty buildings and other articles, corrode metals, and affect life processes. The burning of coal was responsible for large amounts of dust and smoke in former times and still is at numerous locations in Europe. Greater use of liquid and gaseous fuels has considerably reduced these types of pollutants in the United States. Consequently, the "settleable solids" index of pollution has fallen drastically and virtually lost its meaning. However, the pollutants arising from the newer fuels are in some respects more difficult to cope with. This is in considerable measure because of the automobile which expels individually small amounts of pollutants at a great many locations close to the ground. Also, residuals from the combustion of the newer fuels are particularly important contributors to what has been called secondary pollution.
Secondary pollutants are more intractable, of less predictable effect, and generally speaking more dangerous than primary pollutants. They do not as such arise from any industrial, municipal, or household source—rather they are produced by photochemical interactions between primary pollutants within the atmosphere. The most objectionable pollutants appear to arise from the oxidation, often produced by ozone which is generated by a photochemical reaction between organic substances and oxides of nitrogen, of hydrocarbons which are present in incompletely combusted fuel fumes. This is Los Angeles smog.
Aside from property damage, visibility reduction, and general destruction of the amenities, there is strong circumstantial evidence indicating the adverse health effects of continued exposure to the array of contaminants found in the air of numerous urban areas. Comparison of morbidity and mortality statistics with indices of air pollution suggests that communities with the heaviest air pollution loads tend to rank high in death rates for a number of diseases. There is significant correlation between air pollution and cancer of the esophagus and stomach, lung cancer, and arteriosclerotic disease.
The German magazine, Der Spiegel, has recently reported a variety of findings with respect to air pollution in the Ruhr Basin. The Ruhr and its environs suffer from perhaps greater continuous pollution of the air than any other sizeable area on earth. As the magazine graphically puts it, the industries in this area of 8 million people daily produce a small Pompeii. From the perpetually darkened skies, 1.5 million tons of dust, ashes and carbon as well as 4 million tons of sulfur dioxide descend daily. Aside from such interesting facts as that the waiters in the restaurants in Duisburg change their collars three times a day, Der Spiegel also reports that studies have shown that over 15 percent of the children in the Ruhr showed symptoms of rickets while only half as high a percentage did so in a control city in the Rhine Valley. Moreover, the study shows that teenage children in the Ruhr are significantly lighter and of lesser stature than children in the control city.
Extracted from a paper presented by Allen V. Kneese, of RFF, before the General Board of Christian Social Concerns of the Methodist Church, Washington, DC.