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Under the Clean Air Act Amendments of 1977, EPA is required to review and if appropriate revise the air quality criteria for the primary (health-based) and secondary (welfare-based) national ambient air quality standards (NAAQS) every 5 years. On December 18, 2020, the EPA published a final decision retaining the NAAQS for particulate matter (PM), which was the subject of several petitions for reconsideration as well as petitions for judicial review. As directed in Executive Order 13990, "Protecting Public Health and the Environment and Restoring Science to Tackle the Climate Crisis,” signed by President Biden on January 20, 2021, EPA is undertaking a review of the decision to retain the PM NAAQS. Based on that review, EPA is undertaking a rulemaking to reconsider the December 18, 2020 decision because the available scientific evidence and technical information indicate that the current standards may not be adequate to protect public health and welfare, as required by the Clean Air Act. As part of this reconsideration, EPA intends to develop an updated Integrated Science Assessment (ISA) and revised policy assessment to take into account the most up-to-date science on public health impacts of PM, and to engage with the Clean Air Scientific Advisory Committee (CASAC) and a newly constituted expert PM panel.

Statement of Need:

Under the Clean Air Act Amendments of 1977, EPA is required to review and if appropriate revise the air quality criteria and national ambient air quality standards (NAAQS) every 5 years. On December 18, 2020, EPA published a final rule retaining the NAAQS for particulate matter, without revision. On June 10, 2021, EPA announced that it is reconsidering the December 2020 decision on the air quality standards for PM.

Summary of the Legal Basis:

Under the Clean Air Act Amendments of 1977, EPA is required to review and if appropriate revise the air quality criteria and the primary (health-based) and secondary (welfare-based) national ambient air quality standards (NAAQS) every 5 years.

Alternatives:

The main alternative for the Administrator’s decision on the review of the national ambient air quality standards for particulate matter is whether to retain or revise the existing standards.

Anticipated Costs and Benefits:

The Clean Air Act makes clear that the economic and technical feasibility of attaining standards are not to be considered in setting or revising the NAAQS, although such factors may be considered in the development of state plans to implement the standards. Accordingly, when the Agency proposes revisions to the standards, the Agency prepares a Regulatory Impact Analysis (RIA) to provide the public with illustrative estimates of the potential costs and health and welfare benefits of attaining the revised standards.

Risks:

The reconsideration will build on the review completed in 2020, which included the preparation by EPA of an Integrated Review Plan, an Integrated Science Assessment, and also a Policy Assessment, which includes a risk/exposure assessment, with opportunities for review by the EPA's Clean Air Scientific Advisory Committee (CASAC) and the public. These documents informed the Administrator's final decision to retain the PM standards in 2020. As a part of the reconsideration, EPA will prepare an updated Policy Assessment and a Supplement to the Integrated Science Assessment, which will be reviewed at a public meeting by the CASAC. These documents will inform the Administrator’s proposed decisions on whether to revise the PM NAAQS, and will take into consideration these documents, CASAC advice, and public comment on the proposed decision.