Approval and Promulgation of Implementation Plans; State of Missouri, Limited Maintenance Plan for the St. Louis Nonclassifiable Maintenance Area for the 8-Hour Carbon Monoxide National Ambient Air Quality Standard

The Environmental Protection Agency (EPA) is taking direct final action to approve revisions to the State Implementation Plan (SIP) submitted by the State of Missouri relating to the Limited Maintenance Plan for the St. Louis area for the 8-Hour Carbon Monoxide (CO) National Ambient Air Quality Standard (NAAQS). On April 8, 2014, the Missouri Department of Natural Resources (MDNR) submitted to EPA a second 10-year maintenance plan for the St. Louis area for the CO NAAQS. This maintenance plan addresses maintenance of the CO NAAQS for a second 10-year period beyond the original redesignation. In accordance with the requirements of the Clean Air Act (CAA), EPA is approving the revision because the State adequately demonstrates that the St. Louis Maintenance area will maintain air quality standards for CO through the year 2022.