NAAQS

The National Ambient Air Quality Standards (NAAQS) are standards established by the United States Environmental Protection Agency that apply for outdoor air throughout the country. Primary standards are designed to protect human health, including sensitive populations such as children, the elderly, and individuals suffering from respiratory disease. Secondary standards are designed to protect public welfare (e.g. building facades, visibility, crops, and domestic animals).
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National Ambient Air Quality Standards

National Ambient Air Quality Standards

National standards set by the Environmental Protection Agency under authority of the Clean Air Act; NAAQS define the maximum allowable concentrations of specified air pollutants in outdoor (ambient) air. NAAQS have been set for carbon monoxide, particulate matter, sulfur oxides, nitrogen dioxide, lead, and ozone. "Primary" NAAQS protect human health, with a margin of safety; "secondary" NAAQS protect human welfare, which includes effects on soils, water, crops, vegetation, materials, etc.
  

Standards established by EPA that apply for outdoor air throughout the country. (See: criteria pollutants, state implementation plans, emissions trading.)