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 1 9805 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 UT 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 original emission. Sulfur dioxide and nitrogen oxide emissions from the central and eastern U. S. Are causing acid rain in New York State, New England, and eastern Canada. The pH level, or relative acidity, Of many freshwater lakes in that region has been altered so dramatically by this rain that entire fish populations have been destroyed. Similar effects have been observed in Europe.
Sulfur dioxide emissions and the subsequent formation of sulfuric acid can also be responsible for the attack on limestone and marble at large distances from the source. The worldwide increase in the burning of coal and oil since the late sass has led to ever increasing concentrations of carbon dioxide. The resulting “greenhouse effect”, which allows solar energy to enter the atmosphere but reduces the remission of infrared radiation from the earth, could conceivably lead to a warning trend that might affect the global climate and lead to a arterial melting of the polar ice caps.
Possibly an increase in cloud cover or absorption of excess carbon dioxide by the oceans would check the greenhouse effect before it reached the stage of polar melting. Nevertheless, research reports released in the U. S. In the 1 sass indicate that the greenhouse effect is definitely under way and that the nations of the world should be taking immediate steps to deal with it. History In the U. S. The Clean Air Act of 1967 as amended in 1970, 1977, and 1990 is the legal basis for air-pollution control throughout the U. S. The Environmental
Protection Agency has primary responsibility for carrying out the requirements of the act, which specifies that air-quality standards be established for hazardous substances. These standards are in the form of concentration levels that are believed to be low enough to protect public health. Source emission standards are also specified to limit the discharge of pollutants into the air so that air-quality standards will be achieved. The act was also designed to prevent significant deterioration of air quality in areas where the air is currently cleaner than the standards require.