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Regulation Update for the Reconsidered Particulate Matter NAAQS: The EPA Administrator has signed a final particulate matter (PM) NAAQS rule, and the rule is being submitted to the Federal Register for publication. Specifically, this rule will lower the primary annual NAAQS for particulate matter that is 2.5 micrometers and smaller (PM2.5).

Here is a quick summary of what the EPA final rule will do:

  • The primary annual PM2.5 NAAQS will be lowered from the current value of 12 micrograms/cubic meter to 9 micrograms/cubic meter.
  • The lowered PM2.5 NAAQS will take effect 60 days after the publication date of the final rule in the Federal Register.
  • The EPA will designate PM2.5 nonattainment areas within two years of the final publication date in the Federal Register.
  • States will have 18-months following designations to submit their State Implementation Plan (SIP).
  • Designations will most likely be based on the monitoring data collected between 2022 and 2024.
  • After the effective date, the new PM2.5 NAAQS will apply immediately for air permitting purposes.


Here’s a quick summary at what the EPA final rule will not do:

  • The EPA did not change the 24-hour primary standard (which remains at 35 micrograms/cubic meter).
  • The EPA did not change any of the secondary standards.


So, what does this mean for New Source Review (NSR) air permitting? Companies with projects that emit PM2.5 will need to meet the new/lower PM2.5 NAAQS.  The larger a project is in terms of PM2.5 emissions, the harder it will be for the project to “model in” for NAAQS compliance demonstration purposes.

Want to find out more, have any questions, or would you like assistance in navigating the new NAAQS requirements??  If so, contact the professionals at Spirit Environmental and we’ll be glad to help.

If you are interested, a copy of the EPA finalized Pre-Publication version of the rule can be found here:

Final Reconsideration of the National Ambient Air Quality Standards for Particulate Matter (

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