The Illinois Environmental Protection Agency (Illinois EPA) submitted a revised version of the Illinois State Implementation Plan (IL SIP) to the United States Environmental Protection Agency (USEPA) on August 6, 2016 in order to update the rules as follows:

  • Include the 2015 primary annual ozone (O3) National Ambient Air Quality Standards (NAAQS);
  • Address the USEPA's revocation of the 1997 O3 NAAQS;
  • Add timing requirements for "flagging of exception events" and the submission of documentation supporting exceptional events for the initial area designations for the 2015 primary O3 annual NAAQS; and
  • Add USEPA-promulgated monitoring methods for multiple NAAQS.

On August 11, 2016 and May 30, 2017, the Illinois EPA submitted additional updates to the methods used by the State of Illinois to monitor air quality for several NAAQS. These two IL SIP revisions were submitted to incorporate the EPA's revised monitoring methods promulgated during the periods from January 1, 2014 through December 18, 2014 and January 1, 2016 through July 13, 2016, respectively.

These IL SIP revisions update the State of Illinois air regulations to be "identical-in-substance" to that of the USEPA's rulemakings related to the NAAQS that occurred between January 1, 2014 and June 17, 2016. The USEPA has approved these revisions to the IL SIP and published them as a direct final rule in the Federal Register. This rule will be effective on September 18, 2017, unless any adverse comments are received by August 17, 2017. Additionally, note that several state rules, which are listed in the federal register, have been updated to reflect these IL SIP revisions.