Toxic Air Pollutants
Note: EPA no longer updates this information, but it may be useful as a reference or resource.
Please see www.epa.gov/airtrends for the latest information on Air Quality Trends.
Nature and Sources:
Control of toxic air pollutants differs in focus from control of the six principal pollutants for which EPA has established national air quality standards (discussed earlier). For the six principal pollutants, a variety of control strategies are used in geographic areas where national air quality standards have been violated. In contrast, for toxic air pollutants, EPA has focused on identifying all major industrial sources that emit these pollutants and developing national technology-based performance standards to significantly reduce their emissions. The objective is to ensure that major sources of toxic air pollution are well controlled regardless of geographic location.
EPA's toxic air pollutant program and the NAAQS program complement each other. Many toxic air pollutants are emitted in the form of particulates or as VOC. Control programs to meet the NAAQS for ozone and PM-10 also reduce toxic air pollutant emissions. Likewise, emission requirements under the toxic air pollutants program can significantly help achieve the NAAQS for ozone and PM-10. For example, EPA's final toxic air pollutant regulation for organic chemical manufacturing is expected to reduce VOC emissions (which form ground-level ozone or smog) by an amount equivalent to removing millions of cars from the road.
The toxic air pollutant program is especially important in reducing emissions at or near industrial locations and in controlling pollutants that are toxic even when emitted in small amounts. Companies handling toxic chemicals are required by EPA to develop plans to prevent accidental releases and to contain any releases in the event they should occur.
Health and Environmental Effects:
Trends In Toxic Air Pollutants:
As of October 1996, EPA has issued air toxics standards for 47 source categories, such as chemical plants, oil refineries, aerospace manufacturers, and steel mills, as well as area sources like dry cleaners, commercial sterilizers, secondary lead smelters, and chromium electroplating. When these standards are fully implemented, toxic emissions from stationary sources should be reduced by approximately 35 percent. Toxic emissions from point sources have already declined, a trend that is expected to continue as the result of emissions standards. By the year 2005, EPA projects that the toxic air pollutant program will reduce toxic emissions by 75 percent. Because controls for toxic air pollutants also reduce VOC and PM-10 emissions, over the next 10 years, the program should realize reductions in VOC and PM-10 emissions of more than 4 billion pounds per year.
Preliminary analysis of specific VOC measured in urban locations classified as "serious," "severe," or "extreme" ozone nonattainment (PAMS network - see Ozone section) indicate that ambient concentration levels of certain toxic VOC appear to be declining. For example, as illustrated in the above table, benzene levels showed a significant decline between 1994 and 1995 (approximately 38 percent), possibly as a result of the use of reformulated gasoline in those areas. It should be noted that PAMS measurements have only been taken for 3 years and that continued efforts in the PAMS program are expected to provide more confidence in evaluating the long-term trends of benzene and other toxic VOC.