EPA lowers annual National Ambient Air Quality Standard (NAAQS) for Particulate Matter

February 7th, 2024

The U.S. Environmental Protection Agency today lowered the annual National Ambient Air Quality Standard (NAAQS) for Particulate Matter smaller than 2.5 microns from 12 to 9 micrograms per cubic meter. EPA establishes NAAQS for outdoor, publicly-accessible air to "provide public health protection, including protecting the health of "sensitive" populations such as asthmatics, children, and the elderly." EPA reviews the standards periodically.

View the EPA announcement here: Final Reconsideration of the National Ambient Air Quality Standards for Particulate Matter (PM) | US EPA

This will mean two things:

  • Facilities that need to get air permits, and need to conduct air quality dispersion modeling to document compliance with the NAAQS, will eventually need to use the lowered standard in their analysis. High-profile projects will likely need to document compliance with the new standard immediately. From a brief review of past Epsilon air permitting projects, the new standard should be achievable by most projects in the eastern U.S. (where background particulate levels are lower).
  • States where the background level is above the new standard (generally in the western U.S.) will need to be redesignated as being in nonattainment. That process takes a few years, but air permits for new & modified facilities in those states will eventually need to meet tighter emission limits (Lowest Achievable Emission Rate) and get emissions offsets.

Epsilon Associates obtains air permits for clients nationwide, and can assist with any questions regarding the new standards and how they affect permitting.

Related Epsilon Knowledge Center articles: EPA Proposes Revisions to the Air Quality Standard for Particulate Matter.

About The Experts:

AJ Jablonowski, Principal has experience with a variety of industries, including power production, surface coating, chemical production, waste treatment, metalworking, electronics, food processing, and groundwater treatment. His work includes environmental licensing, compliance and due diligence audits, air permit applications, pollution control studies, accidental release prevention, and regulatory applicability studies. He reviews operations at a variety of industrial and power facilities and recommends process changes for regulatory compliance. He uses strong technical engineering skills and an ability to grasp regulatory nuances as part of his problem-solving approach. He acts as a technical resource for air pollution capture and control options, emissions tracking, and air regulatory interpretations.



Sonja Sax, Sc.D, is an environmental health scientist in Epsilon’s Air Quality Group. Dr. Sax specializes in evaluating exposure and health risk from environmental pollutants. She has over 20 years of experience in environmental regulatory assessment, health impact assessment and cost-benefit analyses. She has managed large multi-year projects advocating for clients involved in litigation or providing permitting support. She has performed indoor and outdoor air quality investigations evaluating exposures and health impacts of airborne gases and particles. She also served as a consultant to the US EPA Clean Air Scientific Advisory Committee for the particulate matter and ozone National Ambient Air Quality Standards. More recently she has worked on projects of all sizes conducting Environmental Justice analysis, modeling of air quality impacts and providing guidance to clients on the best approaches for addressing new EJ regulations in multiple states, including Massachusetts and New Jersey.



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