4 The record articles

Ambient Air Quality Regulatory Changes are Coming

Posted: July 12th, 2022

Authors: Meghan S. 

The Clean Air Act (CAA) authorizes the United States Environmental Protection Agency (U.S. EPA) to establish National Ambient Air Quality Standards (NAAQS) for certain air pollutants.  The rules and regulations that implement the NAAQS are the foundation of State air quality management programs across the United States.  Consequently, revisions to any of the NAAQS and changes to the NAAQS attainment status of a given region often result in negative consequences to both regulators and the regulated community.

There are two primary reasons for regulatory changes around the NAAQS.  First, U.S. EPA is required to periodically review each of the NAAQS [e.g., sulfur dioxide (SO2), nitrogen oxides (NO2), ozone, lead, carbon monoxide (CO), particulate matter less than 10 microns (PM10), and particulate matter less than 2.5 microns (PM2.5)] and that review may result in a determination that the standards should be changed (i.e., become more stringent).  A more stringent NAAQS can mean that it’s more difficult to get a permit for a new or modified facility and can mean extra regulatory requirements in areas that are not attaining a new NAAQS.  U.S. EPA is currently reviewing the NAAQS for ozone, lead, and PM2.5.

Second, state and local regulatory agencies install and operate ambient air quality monitors to collect data and analyze whether areas are in compliance with the NAAQS.  The monitoring data are used to determine whether areas are attaining the NAAQS.  If areas that are not attaining the NAAQS do not improve air quality to attain the NAAQS within a certain amount of time, the classification (e.g., attainment or nonattainment) or the severity (e.g., marginal, moderate, serious, severe, and extreme) of the nonattainment can be changed, which results in significantly more stringent regulatory requirements and  reductions of air permitting major source thresholds for nonattainment pollutants and their precursors [e.g., volatile organic compounds (VOC) and nitrogen oxides (NOX) emissions are precursors to ozone formation].  U.S. EPA recently proposed to reclassify six serious ozone nonattainment areas to severe ozone nonattainment and 31 marginal ozone nonattainment areas to moderate ozone nonattainment areas.  These areas are located in different states across the U.S.

ALL4 will be hosting complimentary NAAQS webinars over the next few months to discuss these changes and their impacts to the regulated community.  To discuss how these changes may affect your facility, please contact me or your ALL4 project manager.

Upcoming/Past Events (Recordings Available):

NAAQS to Basics (Aug 11)

New Zones For Ozone NAAQS (Oct 5)


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