Ozone NAAQS Revisions Proposed



On November 25, 2014, the U.S. EPA proposed to strengthen the National Ambient Air Quality Standards (NAAQS) for ground-level ozone.  The current primary ozone standard (finalized in 2008) is 75 ppb.  Two new NAAQS for ozone have been proposed, a primary (health based) standard as well as a secondary (welfare based) standard, both proposed as 8-hour standards set at 65 -70 ppb.  EPA is also proposing and/or requesting comments on the following:

  • Feasibility of even lower ozone standards including 60 ppb
  • Proposed revision to the Air Quality Index (AQI)
  • Possible revisions to the Prevention of Significant Deterioration (PSD) program to add a transitional provision to grandfather PSD projects
  • Revisions to the O3 monitoring seasons for certain areas

The proposal was published in the Federal Register on December 17, 2014, and the public comment period ends March 17, 2015.  EPA plans to hold public hearings on January 29, 2015 in Arlington, TX and Washington, DC and February 2, 2015 in Sacramento, CA.

At this time, EPA’s timeline for making the associated air quality attainment designations is as follows:

  • October 2015:  The final rule for the Ozone standard will be promulgated
  • October 2016:  EPA will make attainment recommendations
  • October 2017:  EPA will make final attainment designations based on 2014-2016 monitoring data
Potential Implications of the Proposed Standard

The proposed standard is very stringent.  EPA’s data indicates that if the standard is finalized at 70 ppb, 358 counties nationwide would violate the standard (based on 2011-2013 monitoring data).  Using the same data, if the standard is set at 65 ppb, an additional 200 counties would violate the standard.  This map from the EPA website illustrates the areas that could potentially violate the standard based on 2011-2013 data.

EPA Map - Ozone numbers

Because the revised standard is only proposed and because EPA is considering the grandfathering of projects that are in the pipeline, there is currently no known cut-off date for facilities that are submitting PSD applications.  If EPA finalizes the rule and hundreds more areas become classified as nonattainment, major sources or major modifications in those jurisdictions will be required to go through the Non-Attainment New Source Review permitting process, rather than the PSD process. Due to the stringency of the proposed standards, facilities planning major capital projects may benefit from moving forward quickly.  (Review the full Federal Register notice.)