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Air Quality Program

Standards and Plans

Federal and state agencies set air quality standards for outdoor air. The purpose of these standards is to prevent air pollution from reaching levels that harm public health and welfare. When an area of a state does not meet a standard, the state must develop a plan to clean up the air.

National Standards

EPA sets standards for the entire country for air pollutants called criteria pollutants. These federal standards are called national ambient air quality standards (NAAQS). States monitor air quality in different areas to find out if the areas are meeting the NAAQS. The federal list of criteria pollutants are:

  • Ground-level ozone (O3)
  • Particulate Matter (PM10 and PM2.5)
  • Carbon monoxide (CO)
  • Nitrogen dioxide (NO2)
  • Sulfur dioxide (SO2)
  • Lead (Pb)

There are both national and state standards for most criteria pollutants. States may set standards at different levels than the federal levels for their areas. However, states cannot set levels any higher than EPA is. In other words, state standards must be at least as protective as the federal standards.

Determining if Air Quality Meets National Standards

When EPA sets or revises a national standard, Washington uses air monitoring data to determine if air quality in the state meets the new or revised standard. Based on this data, Washington can make recommendations to EPA about how to designate areas of the state. EPA will make the final decision about how to designate each area. Possible designations are:

  • Attainment (meeting a standard)
  • Nonattainment (not meeting a standard)
  • Unclassifiable (not enough information to classify)

Air Quality State Implementation Plans (SIPs)

The Federal Clean Air Act requires states to develop plans for protecting and maintaining air quality in all areas of the state. It also requires states to develop specific plans for bringing nonattainment areas back into attainment. The plans are called State Implementation Plans (SIPs). Learn more about SIPs and see SIP documents.