US EPA has initiated the reconsideration of recent changes to prevention of significant deterioration (PSD) regulations, which expects to complete by June 2014. This rulemaking is in response to the January 22, 2013, U.S. Court of Appeals for the District of Columbia Circuit decision that vacated the Significant Monitoring Concentrations (SMCs) and two provisions in EPA’s PSD regulations containing Significant Impact Levels (SILs) that were contained in the 2010 final rule promulgating fine particulate matter (PM2.5) increments, SMCs, SILs, and for PM2.5.

This rulemaking will remove the PM2.5 SMCs from the PSD regulations, and address the court’s decision regarding SILs. This rulemaking will also re-propose for public comment two provisions of the rule that were not addressed in that court decision. The Texas Commission on Environmental Quality (TCEQ) filed a Petition for Reconsideration to the Administrator regarding several provisions contained in the 2010 final rule. In response to the TCEQ petition, EPA agreed to reconsider, by re-proposing, the following three provisions:

  1. The revised definition of “baseline area” that includes a new significance level for PM2.5, which is used for determining whether a particular attainment or unclassifiable area should be included in the baseline area for the PM2.5 increments;
  2. The requirement that PM2.5 precursor emissions be included in the significant impact analysis; and
  3. The level selected for the Significant Monitoring Concentration for PM2.5.
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