Data / Federal rules / 2024-29463

Review of the Secondary National Ambient Air Quality Standards for Oxides of Nitrogen, Oxides of Sulfur, and Particulate Matter

The Environmental Protection Agency published this final rule in the Federal Register on December 27, 2024. It took effect on January 27, 2025.

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What the agency says

Based on the Environmental Protection Agency's (EPA's) review of the air quality criteria for ecological effects and secondary national ambient air quality standards (NAAQS) for oxides of nitrogen (N oxides), oxides of sulfur (SO<INF>X</INF>), and particulate matter (PM), the EPA is revising the existing secondary sulfur dioxide (SO<INF>2</INF>) standard to an annual average, averaged over three consecutive years, with a level of 10 parts per billion (ppb). Additionally, the Agency is retaining the existing secondary standards for N oxides and PM, without revision. The EPA is also finalizing revisions to the data handling requirements for the secondary SO<INF>2</INF> NAAQS.

Key facts

Document number: 2024-29463
Type: Final rule
Action: Final rule
Agency: Environmental Protection Agency
Published: December 27, 2024
Takes effect: January 27, 2025
Dates: This final rule is effective on January 27, 2025.
Docket: EPA-HQ-OAR-2014-0128; FRL-5788-05-OAR
Regulation ID (RIN): 2060-AS35
Code of Federal Regulations: 40 CFR 50
Topics: Air pollution control; Environmental protection; Nitrogen dioxide; Particulate matter; Sulfur oxides
Significant: Yes, under Executive Order 12866
Pages: 97

The document on federalregister.gov PDF

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Everything from the Environmental Protection Agency · Rules on air pollution control · Rules on environmental protection · Rules on nitrogen dioxide · Published in December 2024

Read from the Federal Register API, last updated 2026-10-23. The document on federalregister.gov is the official record; dates and dockets can change through later corrections. Free to reuse with credit to SpecStream under CC BY 4.0.