Latest Findings on National Air Quality – Status and Trends Through 2006. Environmental Protection Agency Office of Air Quality Planning and Standards, Air Quality Assessment Division, Research Triangle Park, North Carolina, EPA-454/R-07-007, January 2008.
“The “Air Trends Online” project provides information on air pollution trends in the United States. The effort was launched in 1972 as a result of the Clean Air Act. Each year EPA tracks the levels of the six criteria pollutants (particulate matter, ground-level ozone, carbon monoxide, sulfur dioxide, nitrogen oxides, and lead) in the air and how much of each pollutant (or the pollutants that form them) is emitted from various pollution sources. EPA looks at these numbers year after year to see how the pollutants have changed over time. Air quality data for this effort come from about 3000 ambient air monitors operated by state, local, and tribal air agencies, the National Park Service, and EPA. Much of the emissions data are obtained from emission source operators by EPA, or by state, local, and tribal governments. The rest of the emission inventory data are estimated by EPA from indirect information, such as vehicle miles traveled or population. The effort is used by EPA, tribal, state, and local governments along with various stakeholders to characterize the levels of the criteria pollutants in the air and the amounts of emissions from various sources to determine how both have changed over time and to summarize the current status of air quality. In addition to providing figures showing national-average air quality trends, the project also produces tables that show various air quality statistics at a geographically specific level.”
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