The preface of EPA's Air Quality Criteria for Sulfur Oxides, the document which is the basis for EPA's determination as to the appropriate primary and secondary standards for sulfur oxides, likewise states (p. iii):

If all of man's previous experience in evaluating environmental hazards provides us with a guide, it is likely that improved knowledge will show that there are identifiable health and welfare hazards associated with air pollution levels that were previously thought to be innocuous.

As EPA stated, the lack of any threshold level for health danger from air pollution is supported by our experience in other fields. While radiation has long been recognized as dangerous, it was first thought that a threshold level existed below which no harm was caused. National Council on Radiation, Protection and Measurements, Basic Radiation Protection Criteria, preface (1971). Further study has indicated that no threshold level for exposure is known and permissible radiation exposure has been substantially lowered since the standards were introduced in 1934. Id. at 55; Advisory Committee on the Biological Effects of Ionizing Radiations, National Academy of Sciences, Report on the Effects on Populations of Exposure to Low Levels of Ionizing Radiation, pp. 1, 7 (1972); Taylor, Radiation Protection Standards, p. 101 (1971).

Asbestos was once considered so innocuous that in 1945 even shipyard workers handling asbestos insulation were deemed not to be in a hazardous occupation. Brodine, Point of Damage, Environment, May 1972, pp. 2, 13. Since that time, asbestos has been recognized as causing asbestosis, lung cancer, and other respiratory ailments. Committee on Biologic Effects of Atmospheric Pollutants, National Academy of Sciences, Asbestos, The Need for and Feasibility of Air Pollution Controls, pp. 1, 30 (1971). Now, concerned over asbestos particles in the ambient air, EPA has found that no safe exposure level for as

bestos has been established and has proposed national emission standards. 36 Fed. Reg. 23239; EPA, Background Information: Proposed National Emission Standards for Hazardous Air Pollutants, pp. 4-5 (1971). EPA has also recently found that mercury and beryllium are hazardous and made them subject to proposed national emission standards. 36 Fed. Reg. 23239; EPA, Background Information, supra, pp. 10, 15-6. A pollutant resulting from the aniline-dye and benzene industries now appears to cause increased occurrence of bladder cancer among not only workers in these industries but also residents in the vicinity after long-term exposure to a relatively low level of pollution. Scientists' Institute for Public Information, Biological Effects of Air Pollution, pp. 9-13 (1970).

2

In recent years, new scientific studies have produced evidence that pollution at levels below the secondary standards has serious health effects. A detailed analysis has been made of mortality rates from heart disease, arteriosclerosis, and certain forms of cancer and of congenital defects in 38 metropolitan areas as compared to their levels of air pollution. The report concluded that "mortality rates of cancer and heart disease [were] very significantly positively correlated with atmospheric concentrations of both SO, and No2." Hickey, et al., Ecological Statistical Studies on Environmental Pollution and Chronic Disease in Metropolitan Areas of the United States, Regional Science Research Institute Discussion Paper Series, No. 35, pp. 56, 79 (1970). This correlation existed at all levels of pollution. The report further found the statistics supported the conclusion that the chemicals involved in air pollution are mutagenic, i.e., they behave like radiation by causing changes in basic body cells and raising serious dangers of congenital defects and cancer. Id. at 56-59, 80.

A study in New York City found a direct relationship between the levels of air pollution and deaths from respiratory and heart disease. Hodgson, Short-term Effects of Air Pollution on Mortality in New York City, 4 Environmental Science and Technology 589 (1970). The report found that there was no threshold level and that the relationship existed for lower, as well as higher, levels of pollution. Id. at 594. Lower-level air pollution appears to be a causative factor in prostatic and stomach cancer. Winkelstein & Kantor, Prostatic Cancer: Relationship to Suspended Particulate Air Pollution, 59 American Journal of Public Health 1134 (1969); Winkelstein & Kantor, Stomach Cancer, 18 Archives of Environmental Health 544 (1969).

A recently disclosed EPA study provides dramatic evidence of the serious health effects of pollution levels below the secondary standards. It noted that recent studies had found "unequivocal evidence that the levels of sulfate necessary to cause adverse health effects were one to two orders of magnitude lower than with SO, or total suspended particulate." EPA, Draft of Summary Report on Suspended Sulfates and Sulfuric Acid Aerosols, p. c (Dec. 1972). This means that sulfates affect health at onetenth to one-hundredth the level of the primary standards for sulfur oxides (80 micrograms per cubic meter), i.e., at a level of only .8 to 8 micrograms per cubic meter. Analysis of asthma attacks in the metropolitan New York area showed a threshold level for increased mortality from sulfate levels of 7.3 micrograms per cubic meter (id. at 66) and a study in Utah showed a threshold level for asthma aggravation from suspended sulfates of only 1.4 micrograms per cubic meter (id. at 67). Since as much as 50 percent of sulfur oxides convert to sulfates within a quarter mile of their source (Southwest Energy Study, supra, p. 9-14), it is obvious that, if sulfur oxides are at the secondary level of 60 micrograms per cubic

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meter, the amount of sulfates which result will often be far higher than the extremely low levels causing serious health effects.

Another EPA draft report recently made public similarly links suspended sulfates with health effects, and characterizes these pollutants as a "major public health problem." EPA, Health Consequences of Sulfur Oxides, p. 790 (Sept. 1972). "The most important conclusion. reached from the present threshold summary was that short-term exposures to low levels of suspended sulfates result in adverse health effects." Id. at 793. The report concluded that, until more is known about the effects of sulfur dioxide, sulfates, and their interaction, "it would be prudent to control ambient sulfur dioxide much more stringently than is now planned." Id. at 793a.

EPA scientists involved in its studies on the effects of air pollution have stated that asthma attacks increase when sulfur oxides reach 50 percent of the level of the secondary standards and that particulate levels which were one-third, as high as the secondary standards aggravated chronic heart and lung disease and increased asthma attacks. Washington Post, March 3, 1973, p. A3.

While damage to vegetation at high levels of pollution is well-documented, studies increasingly show damage at levels previously considered "safe." In a detailed study presented for the United Nations Conference on the Human Environment, the government of Sweden cited evidence that air-borne sulfur oxides cause harm to vegetation, including the death of some plants, at only .01 to .02 parts per million (ppm) in comparison to EPA's national secondary standards of .02 ppm for the annual mean and .1 ppm in a 24-hour period. Air Pollution across National Boundaries, Sweden's Case Study for the United Nations Conference on the Human Environment, p. 44 (1971). "[A]n annual mean concentration in the air of 0.02 ppm led to a drop of a few per cent

in the growth rate of the forest." Id. at 44. According to a German study, long-term exposure to SO2 concentrations at or even below the secondary standard has an appreciable effect on the growth, yield, and quality of certain plant species. Guderian & Van Haut, Detection of SO2 Effects upon Plants, translated by HEW, Environmental Health Service, pp. 20, 31 (1970). A study found that over a third of home gardens were damaged by sulfur-dioxide concentrations which averaged annually .009 parts per million, less than half of the secondary standard. EPA, Air Quality Criteria for Sulfur Oxides, p. 65.

A number of materials, such as concrete, steel and textiles, are damaged by sulfates in the air. The rate of deterioration depends on the accumulation of sulfates over time. This damage occurs at all levels of sulfuroxide pollution. EPA, Draft of Summary Report on Suspended Sulfates and Sulfuric Acid Aerosols, supra, p. 76.

We have seen (pp. 22-23) that 40 C.F.R. 51.12 (b) will allow a total increase in pollution emissions in the country. Such an increase in the emission of sulfur and nitrogen oxides, whether or not the ambient air quality is below secondary standards, will increase the phenomenon called "acid rain." In industrial countries, including the United States, these oxides are turning in the atmosphere to sulfuric and nitrous acid and returning to earth as rainfall. See Likens, et al., Acid Rain, Environment, March 1972, p. 33. Sulfuric acid is likely to remain in the atmosphere for a time varying from hours to several weeks and is transported an average of 600 miles. The acid deposited on the ground depends on the concentration resulting from total emissions from widely separated sources. Sweden's Case Study for the United Nations Conference on the Human Environment, supra, pp. 62, 85-88.