Proposed rule · 2025-07937

Air Plan Approval; Colorado; Serious Attainment Plan Contingency Measures for the 2008 8-Hour Ozone National Ambient Air Quality Standards for the Denver Metro/North Front Range Nonattainment Area

The Environmental Protection Agency (EPA) is proposing to approve state implementation plan (SIP) submittals under the Clean Air Act (CAA) that address contingency measures requirements for the 2008 ozone National Ambient Air Quality Standards (NAAQS) for the Denver Metro/North Front Range (DMNFR) ozone nonattainment area. The requirements at issue relate to the area's previous Serious nonattainment classification. The EPA is proposing to find that the State has met the applicable CAA requirements for Serious area contingency measures and is proposing approval of the contingency measures SIP submittals, except that we are not taking action on one of the two identified contingency measures included in the submittals. In addition, the EPA is proposing to approve regulatory revisions that Colorado adopted to implement the submitted motor vehicle coating contingency measure. The EPA is taking this action pursuant to the CAA.