Air Quality Designation; Illinois; Indiana; Revised Designation of Illinois and Indiana 2012 PM2.5

The Environmental Protection Agency (EPA) is proposing to approve Illinois' May 8, 2018 request to revise the designation for the entire state of Illinois from unclassifiable to unclassifiable/ attainment and Indiana's July 3, 2018 request to revise the designation for the Indiana portions of the Chicago IL-IN and Louisville KY-IN (herein referred to as Chicago and Louisville) areas from unclassifiable to unclassifiable/attainment for the 2012 primary and secondary annual fine particulate matter (PM2.5) National Ambient Air Quality Standards (NAAQS). EPA is proposing to approve these requests because valid, quality-assured, and certified ambient air monitoring data show that the PM2.5 monitors in the areas are meeting the 2012 primary and secondary annual PM2.5 NAAQS. This includes data from monitors in Illinois where data substitution rules have been applied consistent with applicable regulations.