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EPA Issues Final Rule Eliminating Significant Impact Levels and Significant Monitoring Concentrations from PM2.5 Prevention of Significant Deterioration Regulations


As reported in the fourth quarter 2012 issue of the Air Quality Letter, on Jan. 22, 2013, the U.S. Court of Appeals for the District of Columbia Circuit ruled on a challenge brought by the Sierra Club to the significant impact levels (SILs) and significant monitoring concentration (SMC) established for PM2.5 in EPA’s Oct. 20, 2010 rule for implementing the PM2.5 National Ambient Air Quality Standards (NAAQS). The court found there was no authority for the SMC established for PM2.5 and, as a result, vacated the SMC. With respect to the PM2.5 SIL, the court vacated and remanded the SIL to EPA at the agency’s request. SILs and SMCs have been important screening tools that have been used to prevent unnecessary Prevention of Significant Deterioration (PSD) permitting delays when the impact of the emission increases are considered de minimis.

On Dec. 9, 2013, EPA issued a final rule that removes the PM2.5 SIL from EPA’s PSD regulations. The final rule also sets the SMC in EPA’s PSD regulations at 0 ug/l, thus triggering the preconstruction monitoring requirement for any increase in ambient concentrations of PM2.5 from a major project. EPA issued the final rule without providing an opportunity for public comment under the “good cause” exemption of the Administrative Procedure Act in light of the court’s prior ruling that vacated the SIL and SMC provisions.

EPA noted that it has already ceased relying on SILs and SMC for PM2.5 when it issues PSD permits as a result of the prior court ruling. It previously advised state and local air agencies to do the same. EPA is encouraging states and local air agencies that still contain PM2.5 SIL and SMC provisions in their EPA-approved SIPs to remove those provisions as soon as feasible, which may be in conjunction with the next otherwise planned SIP revision. However, EPA explained that any such provisions as reflected in existing SIPs are unlawful and may not be applied even prior to the removal of such provisions from the SIP.

Finally, EPA notes that it will initiate a separate rulemaking in the future regarding the PM2.5 SILs that will address the court’s concerns as expressed in the January 2013 remand ruling. It is expected that any promulgation of SILs for PM2.5 by EPA will be challenged by environmental interest groups based on a claim that they are universally invalid and unauthorized under the Clean Air Act.

To view a complete PDF of the Fourth Quarter 2013 issue of the Air Quality Letter, click HERE.

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