Approval and Promulgation of Air Quality Implementation Plans; Illinois; Oxides of Nitrogen Regulations

On February 23, 2001, Illinois submitted a rule to control emissions of oxides of nitrogen ( NO<INF>X</INF>) from electric generating units (EGU). Illinois' EGU rule represents a key portion of the State's response to EPA's October 27, 1998 NO<INF>X</INF> State Implementation Plan (SIP) Call. Illinois adopted other rules to regulate NO<INF>X</INF> emissions from non-EGU and cement kilns and these rules are addressed in other rulemakings. In EPA's proposed rule on the adequacy of Illinois' EGU rule, we noted that the rule could not be approved unless the State changed a compliance delay provision to meet the provisions of compliance in the EPA model rule. The State made this change, as well as other changes we recommended, and EPA is taking this final action to approve the rule. The rule also provides NO<INF>X</INF> emission reductions to support attainment of the 1-hour ozone standard in the Chicago-Gary-Lake County ozone nonattainment area.