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EPA strengthens fine particulate matter air quality standards

Final rulemaking revises the annual primary standards

Posted February 9, 2024

The Environmental Protection Agency (EPA) finalized its reconsideration of the National Ambient Air Quality Standards for Particulate Matter (NAAQS PM), strengthening the annual primary emissions limit of fine particulate matter (PM2.5), also known as soot.

What changed?

Under the Clean Air Act, EPA sets primary and secondary NAAQS. Primary standards focus on protecting human health, while secondary standards concentrate on protecting public welfare (e.g., preventing environmental damage).

In the finalized NAAQS, EPA strengthened the primary annual PM2.5 standard from 12 micrograms per cubic meter to 9 micrograms per cubic meter. The agency also:

  • Revised the Air Quality Index to improve public communications about health risks from PM2.5 exposures, and
  • Added a monitoring factor to better protect air quality in communities overburdened by air pollution.

What didn’t change?

The agency maintained:

  • The secondary annual PM2.5 standards,
  • The primary and secondary 24-hour PM2.5 standards, and
  • The primary and secondary coarse particulate matter (or PM10) standards

Does this affect my facility?

Upon the effective date of the final rule, all applicants for permits to construct a new major source or make a major modification to an existing stationary source must conduct an air quality analysis that considers the revised PM2.5 NAAQS. Facilities with a Prevention of Significant Deterioration (PSD) permit in progress must show the new or modified source won’t violate or cause a violation of the new annual primary PM2.5 NAAQS.

When EPA establishes a new NAAQS or revises an existing one, it begins a years-long process to implement the new standards in states:

  • EPA designates areas as either meeting (attainment) or not meeting (nonattainment) the new standards.
  • State and local air agencies develop and submit to EPA infrastructure State Implementation Plans (SIPs) to confirm air quality management programs are in place.
  • Once EPA designates areas, state and local air agencies with nonattainment areas develop and submit to the agency SIPs with the strategies and emissions control measures planned to meet the NAAQS.
  • EPA then reviews the SIPs. It either approves all or parts of a SIP or disapproves the plan. Any control measures EPA approves are immediately enforceable in federal court.

Now is the time to proactively consider ways your facility can further limit PM2.5 emissions. Your organization will be better prepared to comply with any future PM emissions control regulations.

This article was written by Adriana Lucus of J. J. Keller & Associates, Inc.

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