Contents Notes |
Electricity is critical to the nation's economy and standard of living. The nation depends on a variety of fuels to generate this electricity, including coal, natural gas, nuclear power, oil, and renewable sources. While fossil fuels-coal, natural gas, and oil-account for more than two thirds of our electricity, generating units that burn these fuels are major sources of airborne emissions that pose human health and environmental risks. Two of the substances emitted, sulfur dioxide and nitrogen oxides, have been linked to respiratory illness and acid rain. A third, carbon dioxide, has been linked to global climate change and its potential adverse effects, including drought and severe weather conditions. Addressing these concerns without compromising economic and energy goals continues to pose significant challenges. To help limit emissions and protect air quality, the Environmental Protection Agency (EPA), under the Clean Air Act, regulates emissions of sulfur dioxide and nitrogen oxides from a variety of sources including electricity generating units that burn fossil fuels, other industrial sources, and automobiles. EPA does not regulate carbon dioxide. Under the Clean Air Act, EPA requires certain electricity generating units built or modified after August 17, 1971, to meet uniform national emissions standards for the regulated substances. 1 Units built before that date that have not undergone modifications do not have to meet these standards. |