National Ambient Air Quality Standards
(NAAQS)
The Clean Air Act, which was last amended in 1990, requires EPA to set National Ambient Air Quality Standards (NAAQS) for
wide-spread pollutants from numerous and diverse sources considered harmful to public health and the environment. The Clean
Air Act established two types of national air quality standards. Primary standards set limits to protect public health,
including the health of "sensitive" populations such as asthmatics, children, and the elderly. Secondary standards set limits
to protect public welfare, including protection against visibility impairment, damage to animals, crops, vegetation, and
buildings. The Clean Air Act requires periodic review of the science upon which the standards are based and the standards
themselves.
EPA has set NAAQS for six principal pollutants, which are called "criteria" pollutants. They are listed below. For a
summary table of the current NAAQS, click on the following link: NAAQS Table.
For further information about the current or prior review of any of the NAAQS or information related to the implementation
of control programs designed to attain the standards, please go the links listed below: