Reviewing National Ambient Air Quality Standards (NAAQS): Scientific and Technical Information
The Clean Air Act requires EPA to review the standards – and the science behind them – periodically to determine whether changes are warranted. Learn more about EPA's NAAQS review process.
The Clean Air Act requires EPA to set National Ambient Air Quality Standards (NAAQS) for pollutants that are common in outdoor air, considered harmful to public health and the environment, and that come from numerous and diverse sources.
The statute established two types of national air quality standards: primary standardsNational ambient air quality standards designed to protect public health with an adequate margin for safety. and secondary standardsNational ambient air quality standards designed to protect the public welfare from adverse effects, including those related to effects on soils, water, crops, vegetation, man-made (anthropogenic) materials, animals, wildlife, weather, visibility, and climate; damage to property; transportation hazards; economic values, and personal comfort and well-being.. This website provides scientific and technical information about the current or prior review of the NAAQS for each of the six criteria pollutants.