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Six Common Air Pollutants

Process of Reviewing the Standards

Reviewing the National Ambient Air Quality Standards is a lengthy undertaking. It begins with an Integrated Review Plan (IRP) that lays out an outline, process, and schedule for the review. A workshop is held to gather input from the Clean Air Scientific Advisory Committee (CASAC), other scientists, and the public regarding questions from the last review and any new science issues that have come up since the last review.

After the IRP is drafted, commented on, and finalized, EPA does an Integrated Science Assessment and a Risk/Exposure Assessment. The Science Assessment is a synthesis and evaluation of policy-relevant scientific studies. The Risk/Exposure Assessment focuses on human health or welfare-related risk and exposure. Each of these documents undergoes CASAC review, public comment, and review by experts in other Federal agencies.

Next, EPA develops a Policy Assessment document that helps translate the science from the Science Assessment and the Risk/Exposure Assessment into terms that can be used for making policy decisions. As with each other step, the Policy Assessment undergoes rigorous review by the scientific community, industry, public interest groups, the general public, and CASAC.

The EPA Administrator then determines whether it is appropriate to propose revisions to the standards based on the scientific and policy assessments. Finally, as required by the Clean Air Act, EPA issues a proposed rule for public comment. Taking all comments on the proposed rule into consideration, EPA issues a final rule.

More information on the NAAQS review process.

Additional documents related to the particle pollution standards.

Additional documents related to the ozone standards.

Additional documents related to the carbon monoxide standards.

Additional documents related to the sulfur dioxide standards.

Additional documents related to the lead standards.

Additional documents related to the nitrogen dioxide standards.

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