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The National Ambient Air Quality Standards are the Environmental Protection Agency’s limits on the amount of the seven criteria pollutants that are permissible in the ambient air. The primary standard is human health-based; the secondary standard is environmentally-based. The environmentally-based secondary standards prevent damage to crops, animals, vegetation, and buildings.
The Clean Air Act requires that each pollutant’s standards be reviewed against the latest health-based information every five years to determine if the standards need to change to protect human health with an adequate margin of safety for sensitive populations (children, elderly and individuals suffering from respiratory or heart disease).
For more information about the NAAQS, go to www.epa.gov/air/criteria.html.