The permissible upper limit for a pollutant in ambient air, established by the state or federal government, that serves as a target in local air quality improvement or protection programmes. It is based on the maximum acceptable average concentrations of air pollutants during a specified period of time. The primary standard protects public health, and the secondary standard protects public welfare. See also criteria pollutant, hazardous air pollutant, National Ambient Air Quality Standards, primary ambient air quality standards, secondary ambient air quality standards.
Subjects: Environmental Science.