Air Plan Approval; Illinois; Redesignation of the Illinois Portion of the St. Louis, MO-IL Area to Attainment of the 1997 Annual Standard for Fine Particulate Matter

The Environmental Protection Agency (EPA) is redesignating the Illinois portion of the St. Louis, MO-IL, nonattainment area (hereafter, "the St. Louis area") to attainment for the 1997 fine particulate matter (PM<INF>2.5</INF>) annual national ambient air quality standard (NAAQS or standard). The Illinois portion of the St. Louis area includes Madison, Monroe, and St. Clair counties, and Baldwin Township in Randolph county. EPA is taking this action because it has determined that the St. Louis area is attaining the annual 1997 PM<INF>2.5</INF> standard based on the most recent three years of certified air quality data. EPA is also approving a revision to the Illinois state implementation plan (SIP) for maintaining the 1997 annual PM<INF>2.5</INF> NAAQS through 2030. Illinois' maintenance plan submission includes an updated emissions inventory, which includes emissions inventories for PM<INF>2.5</INF>, nitrogen oxides (NO<INF>X</INF>), sulfur dioxide (SO<INF>2</INF>) volatile organic compounds (VOCs) and ammonia. The maintenance plan submission also includes motor vehicle emission budgets (MVEBs) for the mobile source contribution of PM<INF>2.5</INF> and NO<INF>X</INF> to the St. Louis PM<INF>2.5</INF> area for transportation conformity purposes. EPA is approving and updating both the emissions inventory and MVEBs. EPA is taking these actions in accordance with the Clean Air Act (CAA) and EPA's implementation rule regarding the 1997 PM<INF>2.5</INF> NAAQS.