4 The record articles

Ozone Nonattainment: Impact to Air Permitting

Posted: May 9th, 2022

Authors: All4 Staff 

Under the Clean Air Act (CAA), the U.S. Environmental Protection Agency (U.S. EPA) sets National Ambient Air Quality Standards (NAAQS) for pollutants considered harmful to public health and the environment. A geographical area (which can vary from a partial county to multiple counties) that does not meet a NAAQS is classified as a nonattainment area.

U.S. EPA set the 2008 ozone standard to 75 parts per billion (ppb) and required all areas of the country to meet this monitored concentration by July 20, 2018. The areas that were not able to demonstrate compliance with this standard have now been classified as an ozone nonattainment area.  U.S. EPA revised the standard to 70 ppb in 2015 but some areas have still not met the 2008 standard and their attainment status is about to change in level of severity.

Serious to Severe Nonattainment

On April 13, 2022, the EPA issued a proposed rule that would change the nonattainment status for six areas. The six areas listed below are currently classified as serious nonattainment areas and failed to meet the 2008 ozone NAAQS by the attainment date. U.S. EPA now proposes to reclassify these areas as severe nonattainment areas. Each area listed will have until July 20, 2027, to demonstrate compliance.

  1. Chicago-Naperville, IL-IN-WI
  2. Dallas-Fort Worth, TX
  3. Denver-Boulder-Greeley-Ft. Collins-Loveland, CO
  4. Houston-Galveston-Brazoria, TX
  5. Morongo Band of Mission Indians
  6. New York-N. New Jersey-Long Island, CT-NJ-NY


Impact to Air Permitting

The nonattainment classification has a direct impact on state air permitting programs and compliance for each facility in the areas noted above. Under the CAA, the major source threshold for a facility located in a serious nonattainment area is 50 tons per year for Nitrogen Oxides (NOx) and Volatile Organic Compounds (VOC). However, the major source threshold in a severe nonattainment area is 25 tons per year for NOx and VOC. Therefore, any facility located within the severe nonattainment area with the potential to emit greater than 25 tons per year of NOx or VOC will be required to obtain a Title V operating permit.  Any new facility with potential emissions greater than or equal to 25 tons per year of NOx or VOC or any modification with an increase greater than or equal to 25 tons per year of NOx or VOC will have to go through nonattainment New Source Review (NSR).  For such facilities that would be new to a Title V operating permit, compliance activities will become more rigorous with respect to recordkeeping and reporting requirements.

Another area that will need to be carefully examined would be emissions netting for new projects at an existing Title V facility. If your facility will be amending an existing NSR permit or starting a new NSR project, the trigger for netting will be reduced and the ratio for emissions offsets will become less favorable. Currently for serious nonattainment areas, the offset ratio is 1.2 to 1 and with a severe nonattainment classification, that will be changed to 1.3 to 1. In other terms, the emissions offset ratio is the ratio of total actual reductions of emissions to total emissions increases of such pollutants. For example, a 1-ton NOx increase would have to be offset with a 1.3-ton NOx decrease in a severe nonattainment area. With more stringent offset ratios permitting activities will become more difficult on the regulated community.


Deadlines for facilities to apply for a first-time Title V permit will be established following issuance of the final rule.  The reclassification will be in place upon the effective date of the final rule and will impact any permit applications that are still being processed for facilities in the areas being reclassified. If your facility has a potential to emit greater than 25 tons per year of NOx or VOC, you may be subject to additional permitting requirements. ALL4 has the expertise to help navigate any new air regulatory requirements that may affect you and your facility. If you have any questions regarding this proposed rule and its impacts, please contact your ALL4 project manager or contact us at info@all4inc.com.


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