On August 24, 2010, U.S. EPA proposed a rule related to areas that were designated as non-attainment for the former 1-hour ozone National Ambient Air Quality Standard (NAAQS).  Previously, the agency's rules had indicated that, when the 1-hour ozone standard was revoked, states no longer had to retain the nonattainment New Source Review (NA-NSR) provisions for the 1-hour standard (which may have included lower major source thresholds, lower major modification thresholds and higher offset ratios).  As a result of several petitions and the 2006 court decision regarding the South Coast Air Quality Management District v. EPA, U.S. EPA is now proposing rule changes that would seemingly reverse their previous rule on the 1-hour NA-NSR provisions.  Under the proposed rule, states would have to maintain the 1-hour NA-NSR provisions until the 8-hour ozone NAAQS (the 1997 standard of 0.08 ppm) is achieved. 

Although this is a proposed rule (with comments being accepted until September 23, 2010), U.S. EPA has noted that, "States are to comply with the South Coast decision as quickly as possible.  States should take appropriate steps to implement the 1-hour major NSR requirements... without waiting for completion of this rulemaking".

Areas that were either designated as attainment for the 1997 8-hour ozone standard at the time the 1-hour ozone standard was revoked, or that have subsequently achieved attainment of the 1997 8-hour standard, would no longer have to follow the 1-hour NA-NSR provisions.  Instead, Prevention of Significant Deterioration (PSD) requirements would apply in these areas.  U.S. EPA also notes that "this proposal to allow removal of the 1-hour major NSR requirements after an area has attained and been redesignated for the 1997 8-hour NAAQS could be affected by the transition to a newer ozone standard".

While the Chicago area has not yet attained the 1997 8-hour ozone standard, the Illinois EPA has also not continued to apply the 1-hour NA-NSR provisions since the time the 1-hour ozone standard was revoked.  It is known that the Illinois EPA is in the process of demonstrating that Chicago has attained the 1997 8-hour standard, so changes (if any) to Illinois EPA NA-NSR applicability may be short-lived.  The Metro East (St. Louis) area achieved attainment of the 1-hour ozone standard in 2003, and thus this proposed rulemaking will not impact Metro East.  Note that U.S. EPA's proposed rulemaking addresses the NSR program only, and does not state that a lower major source threshold must also be applied to the Title V operating permit program.  Therefore, sites in the Chicago area that have transitioned from a Title V permit to a Federally-Enforceable State Operating Permit (FESOP) should not be impacted by this proposed rulemaking.