Air Plan Approval; Illinois; NAAQS Updates

The Environmental Protection Agency (EPA) is approving 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 2015 primary National Ambient Air Quality Standard (NAAQS) for ozone (O3), add EPA-promulgated monitoring methods for several NAAQS, and address EPA's revocation of the 1997 O3 NAAQS. In addition, the revised rules contain the timing requirements for the ``flagging of exceptional events'' and the submission of documentation supporting exceptional events for the initial area designations for the 2015 primary annual O3 standard. These SIP revisions update Illinois air pollution control regulations to be ``identical-in-substance'' to EPA rulemakings related to the NAAQS that occurred between January 1, 2014 and June 17, 2016.