Environmental Permitting

SO2 NAAQS: What’s Next?

By Timothy P. Fagan, BLR Air Expert
tfagan@blr.com

How were nonattainment designations determined?
Once the NAAQS was set in 2010, EPA and state agencies worked together using monitoring data to determine what areas should be designated nonattainment and establish the area’s boundaries.  The newly designated nonattainment areas were designated as such because each had air quality monitors that measured violations of the standard.

What impact do the nonattainment designations have?
States with SO2 nonattainment areas must develop state implementation plans (SIPs) to demonstrate how SO2 pollution will be reduced to bring the designated areas back into attainment with the SO2 NAAQS.  As a result, industrial facilities may find themselves subject to:

  • Stricter SO2 emissions standards; and
  • The permitting requirements of nonattainment new source review (NSR) for new major sources and major modifications to existing sources instead of or in addition to the permitting requirements of Prevention of Significant Deterioration (PSD).

Are all other areas attaining the standard? 
According to EPA, “the current monitoring network provides relatively limited geographic coverage” and the placement of some of the existing monitors may not be ideal.  Therefore, in many areas the data does not exist to make an accurate attainment status determination.  However, moving and adding monitors to make the coverage comprehensive is extremely expensive. As a result, EPA has developed a strategy of additional monitors combined with computer modeling to identify other areas with unhealthy levels of SO2.  EPA is expected to issue additional SO2 nonattainment designations in 2017 based on modeling and 2020 based on newly deployed monitors.

When do we get to attainment?
States must attain the new SO2 NAAQS “as expeditiously as practicable” but not later than 5 years after the final nonattainment designations are made.   States failing to attain the standard must submit a SIP revision with additional actions to be implemented in order to demonstrate attainment at the end of a 5-year extension.  Therefore, attainment of the 2010 SO2 standards may be staggered over many years, especially with additional nonattainment designations expected in 2017 and 2020.

Additional Resources:


Timothy P. Fagan is a Legal Editor for BLR’s environmental publications, focusing primarily on air quality related topics. Mr. Fagan has covered environmental developments with BLR since 2000. Before joining BLR, he spent 5 years in environmental consulting and was responsible for air quality permitting and compliance for a broad range of industries in both the private and public sector. He received a Bachelor of Science degree in chemical engineering from Villanova University and a Master’s degree in environmental engineering from the Pennsylvania State University.

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