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California Environmental Health Tracking Program

850 Marina Bay Pkwy, P-3
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Last Edited: 9/28/2010

Air Quality Regulation

The Clean Air Act

In 1970, the Clean Air Act was signed into law. Under this law, the Environmental Protection Agency (EPA) limits on how much of a pollutant can be in the air anywhere in the United States. This ensures that all Americans have the same basic health and environmental protections. The law has been amended several times to keep pace with new information.

Under the Clean Air Act the EPA has established standards or limits for six air pollutants, known as the criteria air pollutants:

  • Carbon Monoxide (CO)
  • Lead (Pb)
  • Nitrogen Dioxide (NO2)
  • Sulfur Dioxide (SO2)
  • Ozone (O3)
  • Particulate matter (PM)

These standards, called the National Ambient Air Quality Standards (NAAQS), help protect public health and the environment.

The Clean Air Act established two types of air quality standards:

  • Primary standards which set limits to protect public health. This includes the health of sensitive populations such as people with asthma, children, and the elderly.
  • Secondary standards which set limits to protect public welfare. This includes protection against damage to animals, crops, other plants, visibility and buildings.

The Clean Air Act requires states to develop State Implementation Plans (SIPs) that outline how they will meet these air quality standards. A SIP is a set of the regulations, programs and policies that a state will use to clean up polluted areas.  Learn more about the Clean Air Act on the EPA website.


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Air quality standards in California

California is a leader in the nation for improving air quality standards. The Federal Clean Air Act allows states to adopt additional or more stringent air quality standards than the federal outdoor air standards.

For some pollutants such as particulate matter and ozone, California has set standards that are more protective of public health than their respective federal standards. California also has set standards for some pollutants that are not included in the federal standards.

See the California Air Resources Board (ARB) overview on the California Ambient Air Quality Standards for more information.  A list of the ambient air quality standards for California and the US (PDF) is also available from ARB.


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