Air Plan Approval; Illinois; NAAQS Update

The Environmental Protection Agency (EPA) is proposing to approve revised rules submitted by the State of Illinois as State Implementation Plan (SIP) revisions. The submitted rules update Illinois' ambient air quality standards to include the 2012 primary National Ambient Air Quality Standard (NAAQS) for fine particulate matter (PM2.5), add EPA-promulgated monitoring methods, and address the ``sunset provisions'' in our regulation, finding that the 1971 NAAQS for sulfur dioxide no longer applies to the Lemont and Pekin areas in Illinois. In addition, the revised rules contain the timing requirements for the ``flagging of exceptional events'' and the submitting of documentation supporting the determination of exceptional events for the 2012 primary annual averaged PM2.5 standard.