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Air Quality Planning and Standards

Air Quality

Air pollution comes from many different sources: stationary sources such as factories, power plants, and smelters and smaller sources such as dry cleaners and degreasing operations; mobile sources such as cars, buses, planes, trucks, and trains; and naturally occurring sources such as windblown dust, and volcanic eruptions, all contribute to air pollution. Air Quality can be affected in many ways by the pollution emitted from these sources. These pollution sources can also emit a wide variety of pollutants. The EPA has these pollutants classified as the six principal pollutants (or "criteria pollutants" - as they are also known). These pollutants are monitored by the EPA, as well as national, state and local organizations.

The Clean Air Act provides the principal framework for national, state, and local efforts to protect air quality. Under the Clean Air Act, EPA's Office of Air Quality Planning and Standards (OAQPS) is responsible for setting standards, also known as national ambient air quality standards (NAAQS), for pollutants which are considered harmful to people and the environment. OAQPS is also responsible for ensuring that these air quality standards are met, or attained (in cooperation with state, Tribal, and local governments) through national standards and strategies to control pollutant emissions from automobiles, factories, and other sources.

EPA is dedicated to monitoring the quality of the air we breathe.

For more information about air pollution from mobile sources:
Office of Transportation and Air Quality

For information about the Clean Air Act:
The Plain English Guide to the Clean Air Act

Find out about EPA's air research that supports the air quality standards and other research needs to improve air quality:
Clean Air Research Program

Finding out if the Air we Breathe is Clean

OAQPS is responsible for setting the National Ambient Air Quality Standards (NAAQS), which control pollutants harmful to people and the environment. There are two types of standards, primary and secondary. Primary standards protect against adverse health effects; secondary standards protect against welfare effects, such as damage to farm crops and vegetation and damage to buildings. The six criteria pollutants addressed in the NAAQS are Carbon Monoxide, Nitrogen Dioxide, Lead, Ozone (or smog), Particulate Matter, and Sulfur Dioxide. If the levels of these pollutants are higher than what is considered acceptable by EPA, then the area in which the level is too high is called a nonattainment area. OAQPS monitors very closely many areas for criteria pollutants and attainment.

For more information about NAAQS, visit:

For more information about criteria pollutants, visit:
Six Criteria Pollutants

Through various programs, OAQPS monitors for criteria pollutants. One such program is the Ambient Air Monitoring Program. Through this program, air quality samples are collected to judge attainment of ambient air quality standards, to prevent or alleviate air pollution emergencies, to observe pollution trends throughout regions, and to evaluate the effects of urban, land-use, and transportation planning relating to air pollution. There are other important types of pollution monitoring programs; two of which are Enhanced Ozone Monitoring and Air Pollution Monitoring.

The Air Pollution Monitoring program monitors all of the six criteria pollutants. Measurements are taken to assess areas where there may be a problem, and to monitor areas that already have problems. The goal of this program is to control areas where problems exist and to try to keep other areas from becoming problem air pollution areas.

For more information about Air Quality Monitoring, visit
Monitoring Information

- The Ambient Monitoring Technical Information Center

Working to Clean up the Air

In order to work towards attainment, OAQPS requires that each state containing nonattainment areas to develop a written plan for cleaning the air in those areas. The plans developed are called SIPS or state implementation plans. Through these plans, the states outline efforts that they will make to try to correct the levels of air pollution and bring their areas back into attainment.

If an area does not meet attainment, it's designated a nonattainment area. Nonattainment means that the area is not meeting the levels set in the NAAQS (National Ambient Air Quality Standards). OAQPS lists and follows closely those areas listed as nonattainment and requires that they develop plans for reaching attainment.

For more information about nonattainment areas, visit:
The Green Book

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