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Regulation Update for the 2015 Ozone NAAQS:  The EPA proposed ozone reclassification changes in Texas, and they were published in the Federal Register on January 26, 2024.

The Federal Register publication can be found here: 2024-01525.pdf (

There are three 2015 ozone NAAQS nonattainment areas in Texas: Dallas-Ft Worth (DFW), Houston-Galveston-Brazoria (HGB) and San Antonio (Bexar County). These ozone nonattainment areas are currently classified as “moderate” ozone nonattainment.  However, the proposed rule will reclassify these areas as “serious” ozone nonattainment.

What does this mean for New Source Review (NSR) air permitting?  For DFW and HGB, there is not much change because these areas are currently classified as “severe” ozone nonattainment under the 2008 ozone NAAQS.   The NSR applicability criteria under the 2008 severe classification is more stringent, so there should not be much impact versus the reclassification under the 2015 standard.

On the other hand, the reclassification will have a significant impact on sources operating in San Antonio/Bexar County.  This area is attainment for the 2008 ozone standard and will be experiencing “serious” ozone nonattainment applicability criteria for the first time under the 2015 ozone standard.  Here are some of the applicability threshold changes that will occur in San Antonio (as they apply to the ozone precursors of Nitrogen Oxides [NOx] and Volatile Organic Compounds [VOC]).

  • The definition of a major source is being reduced from 100 tons/year to 50 tons/year,
  • The definition of a major modification is being reduced from 40 tons/year to 25 tons/year,
  • The netting trigger is being reduced from 40 tons/year to 5 tons/year, and
  • If nonattainment new source review (NNSR) permitting is initiated, the offset ratio is being increased from 1.15:1 up to 1.20:1


So, for San Antionio, it will be easier to become a major source for ozone precursors and that makes it easier to trigger NNSR applicability when it comes to air permitting.

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


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