A number of pollutants, including smog, acid rain, and other health hazards, are limited in air quality by the National Ambient Air Quality Standards (NAAQS). Under the Clean Air Act, NAAQS is a national air quality standard established by the United States Environmental Protection Agency (EPA).

NAAQS limit six criteria air pollutants: ozone (O3), lead, atmospheric particulate matter, sulfur oxides (SOx), nitrogen oxides (NOx), and carbon monoxide (CO).

The air quality standards introduced by National Ambient Air Quality Standards (NAAQS) are established to protect our environment with clean air. A quality standard for air identifies the amount of pollution in the air that is permissible without affecting the health of the public. Both the California Air Resources Board (ARB) and the U.S. Environmental Protection Agency (U.S. EPA) are authorized to set ambient air quality standards.

Federal Standards

To prevent and minimize adverse health effects as well as adverse effects on crops, forests, and other resources, EPA has set air quality standards (termed National Ambient Air Quality Standards or NAAQS). A level of ozone in the atmosphere that is at or below standards is considered safe, whereas a level above standards is regarded as a reasonable threat to public health and welfare. Therefore, emissions of certain ozone precursors must be reduced to reduce ozone precursor levels.  

Ozone regulations established by the EPA are 8-hour averages below 0.084 parts per million by volume (ppm(v)). EPA ozone standards fall into two categories: primary standards for public health and secondary standards for public welfare (each standard’s numerical value is the same).