Effects of Air Pollutants

Air. Studies have shown that 2500 years ago lead pollution caused by Greek and Roman silver smelters was a significant problem (4). Based on analysis of lake sediments and Greenland s ice, it was found that lead contamination from smelters in southern and central Europe was carried throughout the northern hemisphere. As long ago as the thirteenth century, air pollution has been linked to the burning of coal (4). The main concern was the smell from the sulfur in the coal and the effects of the soot. It was not until many years later that the effects of air pollution on people s health were discovered. 

The harmful effects of air pollutants on human beings have been the major reason for efforts to understand and control their sources. During the past two decades, research on acidic deposition on water-based ecosystems has helped to reemphasize the importance of air pollutants in other receptors, such as soil-based ecosystems (1). When discussing the impact of air pollutants on ecosystems, the matter of scale becomes important. We will discuss three examples of elements which interact with air, water, and soil media on different geographic scales. These are the carbon cycle on a global scale, the sulfur cycle on a regional scale, and the fluoride cycle on a local scale. 

In general, clinical studies provide evidence on the effects of air pollutants under reproducible laboratory conditions. The exposure level may be accurately determined. The physiological effect may be quantified, and the health status of the subject is well known. This type of study can determine the presence or absence of various endpoints for a given sample group exposed to short-term, low-level concentrations of various air pollutants. 

American Lung Association, "Health Effects of Air Pollution." New York, 1978. 

The indirect pathway by which air pollutants interact with plants is through the root system. Deposition of air pollutants on soils and surface waters can cause alteration of the nutrient content of the soil in the vicinity of the plant. This change in soil condition can lead to indirect or secondary effects of air pollutants on vegetation and plants. 

The effects of air pollution on plants range from subtle to catastrophic, as shown in Fig. 8-1. Historically, these effects have been classified as... 

The nonvisual or subtle effects of air pollutants involve reduced plant growth and alteration of physiological and biochemical processes, as well as changes in the reproductive cycle. Reduction in crop yield can occur without the presence of visible symptoms. This type of injury is often related to low-level, long-term chronic exposure to air pollution. Studies have shown that field plantings exposed to filtered and unfiltered ambient air have produced different yields when no visible symptoms were present (5). Reduction in total biomass can lead to economic loss for forage crops or hay. 

The principal effects of air pollutants on metals are corrosion of the surface, with eventual loss of material from the surface, and alteration in the electrical properties of the metals. Metals are divided into two categories—ferrous and nonferrous. Ferrous metals contain iron and include various types of steel. Nonferrous metals, such as zinc, aluminum, copper, and silver, do not contain iron. 

The major effects of air pollution on fabrics are soiling and loss of tensile strength. Sulfur oxides are considered to cause the greatest loss of tensile strength. The most widely publicized example of this type of problem has been damage to women s nylon hose by air pollution, described in newspaper accounts. The mechanism is not understood, but it is postulated that fine droplets of sulfuric acid aerosol deposit on the very thin nylon... 

Holzworth, G. C., "Some Effects of Air Pollution on Visibility in and Near Cities," Sanitary Engineering Center Technical Report A62-5, Department of Health, Education and Welfare. United States Public Health Service, Cincinnati, OH, 1962. 

An important effect of air pollution on the atmosphere is change in spectral transmission. The spectral regions of greatest concern are the ultraviolet and the visible. Changes in ultraviolet radiation have demonstrable adverse effects e.g., a decrease in the stratospheric ozone layer permits harmful UV radiation to penetrate to the surface of the earth. Excessive exposure to UV radiation results in increases in skin cancer and cataracts. The worldwide effort to reduce the release of stratospheric ozone-depleting chemicals such as chlorofluorocarbons is directed toward reducing this increased risk of skin cancer and cataracts for future generations. 

The U.S. Clean Air Amendments of 1977 define two kinds of air quality standards primary standards, levels that will protect health but not necessarily prevent the other adverse effects of air pollution, and secondary standards, levels that will prevent all the other adverse effects of air pollution (Table 22-7). The amendments also define air quality levels that cannot be exceeded in specified geographic areas for "prevention of significant deterioration" (PSD) of the air of those areas. Although they are called "increments" over "baseline air quality" in the law, they are in effect tertiary standards, which are set at lower ambient levels than either the primary or secondary standards (Table 22-8). 

Discuss the problem caused by cigarette smoking in the evaluation of epidemiological data on the effect of air pollution on respiratory disease. 

An overview of important terms and definitions useful in assessing the potentially harmful effects of air pollutants, and... 

The pernicious effects of air pollution were first documented long ago. As early as 61 C.E., Seneca, a Roman... 

Physiological effects of air pollution are deperrdent on dosage, the ability of the exposed organism to metabolize and excrete the pollution, and the type of pollutant. Many pollutants affect the futretiotring of the respiratory tract some change the structure and function of molecules others can enter the nucleus and turn getres otr or off atrd some cause chromosomal aberrations or mutations that result in cancer. 

Hazardous waste combustors (HWCs) also are regulated under the Clean Air Act (CAA).6 The CAA protects human health and the environment from the harmful effects of air pollution by requiring significant reductions in the emissions of the most dangerous air pollutants. These pollutants are known or suspected to cause serious health problems such as cancer or birth defects, and are referred to as hazardous air pollutants (HAPs). 

Haider SS, Hasan M, Islam F. 1980. Effect of air pollutant hydrogen sulfide on the levels of total lipids, phospholipids cholesterol in different regions of the guinea pig brain. Indian J Exp Biol 18 418-420. 

Peden, D.B., Effect of air pollution in asthma and respiratory allergy, Otolaryngol. Head. Neck. Surg. 114, 2, 242, 1996. 

Llacna, S., et al., Effects of air pollution on haematological parameters in passerine birds, Arch. Environ. Contam. Toxicol., 31, 148, 1996. 

Calvert, J. G. Interactions of air pollutants, pp. 19-101. In National Academy of Sciences-National Research Coundl, Assembly of Life Sciences. Proceedings of the Conference on Health Effects of Air Pollutants. October 3-5, 1973. Prepared for the Committee on Public Works, United States Senate. Committee Print Serial No. 93-15. Washington, D.C. U.S. Government Printing Office, 1973. 

Coffin, D. L., E. J. Blommer. D. E. Gardner, and R. S. Holzman. Effect of air pollution on alteration of susceptibility to pulmonary infections, pp. 75-80. In Proceedings of the 3rd Annual Conference on Atmospheric Contaminants in Confined Spaces. Dayton, Ohio Wright-Patterson Air Force Base, Aerospace Medical Research Laboratories. 1968. 

Hackney, J. D., W. S. Unn, D. C. Uw. S. K. Karuza, H. Greenberg, R. D. Buckley, and E. E. Pedersen. Experimental studies on human health effects of air pollutants. III. Two-hour exposure to ozone alone and in combiiuition with other pollutant gases. Arch. Environ. Health 30 385-390, 1975. 

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