CFish Mr. Nollen
8 May, 1996
Contamination of the atmosphere by gaseous, liquid, or solid wastes or by-products that can endanger human health and the health and welfare of plants and animals, or can attack materials, reduce visibility, or produce undesirable odors. Among air pollutants emitted by natural sources, only the radioactive gas radon is recognized as a major health threat. A byproduct of the radioactive decay of uranium minerals in certain kinds of rock, radon seeps into the basements of homes built on these rocks. According to recent estimates by the U.S. government, 20 percent of the homes in the U.S. harbor radon concentrations that are high enough to pose a risk of lung cancer.
Each year industrially developed countries generate billions of tons of pollutants. The level is usually given in terms of atmospheric concentrations or, for gases in terms of parts per million, that is, number of pollutant molecules per million air molecules. Many come from directly identifiable sources; sulfur dioxide, for example, comes from electric power plants burning coal or oil. Others are formed through the action of sunlight on previously emitted reactive materials. For example, ozone, a dangerous pollutant in smog, is produced by the interaction of hydrocarbons and nitrogen oxides under the influence of sunlight. Ozone has also caused serious crop damage. On the other hand, the discovery in the 1980s that air pollutants such as fluorocarbons are causing a loss of ozone from the earth's protective ozone layer has caused the phasing out of these materials.
Current information about the problem
The tall smokestacks used by industries an utilities do not remove pollutants but simply boost them higher into the atmosphere, thereby reducing their concentration at the site. These pollutants may then be transported over large distances and produce adverse effects in areas far from the site of the...