The United States Environmental Protection Agency (USEPA) approved the redesignation of the Illinois portion of the Chicago-Gary-Lake County, Illinois-Indiana area (Greater Chicago area) to be in attainment of the 1997 8-hr Ozone National Ambient Air Quality Standards (NAAQS) on August 13, 2012. A ‘Maintenance Plan’ to maintain this ozone standard through 2025 was also approved by the USEPA at the time. The Illinois Environmental Protection Agency (IEPA) is proposing to update this ‘Maintenance Plan’ by increasing the Motor Vehicle Emissions Budgets (MVEBs) through a safety margin, which is allowed under the transport conformity regulations (40 CFR Part 93). This revision proposes to increase the Volatile Organic Material (VOM) and Nitrogen Oxide (NOX) MVEBs by twelve (12) and twenty-five (25) tons per day, respectively. The updates reflect the changes in planning assumptions used to calculate the MVEBs. This revision still ensures maintenance and attainment of the 1997 8-hr ozone NAAQS through 2025.

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IEPA is accepting public comments and a request for public hearing till March 17, 2014. A public hearing will be held on March 24, 2014 if a timely request is received.