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Criteria Pollutant SIPs

The EPA periodically reviews the latest science in air quality in order to update the National Ambient Air Quality Standards (NAAQS) for the six principal air pollutants, or “criteria pollutants,” regulated by the Clean Air Act. The Act requires EPA to set standards for pollutants harmful to public health and welfare and the environment. There are two types of standards for each criteria pollutant:

  1. Primary standard: Sets pollution limits to protect public health, including the health of at-risk populations such as asthmatics, children, and the elderly.
  2. Secondary standard: Sets pollution limits to protect public welfare, like visibility in national parks, crop and livestock damages, and infrastructure decay.

When EPA revises the NAAQS, each state, in conjunction with EPA, has to designate certain portions as either meeting the standards (“attainment”) or as not meeting the standards (“nonattainment”). Those areas that are in nonattainment must have a new SIP developed in order to bring the area into attainment, eventually lowering pollution levels and enhancing the environment and protecting public health.

Learn more about each Criteria Pollutant | View Criteria Pollutants >