Approval of Missouri Air Quality Implementation Plans; Infrastructure SIP Requirements for the 2012 Annual Fine Particulate Matter (PM2.5

Due to adverse comments, the Environmental Protection Agency (EPA) is withdrawing the direct final rule for ``Approval of Missouri Air Quality Implementation Plans; Infrastructure SIP Requirements for the 2012 Annual Fine Particulate Matter (PM2.5) National Ambient Air Quality Standard'' published in the Federal Register on October 11, 2017. Section 110 of the CAA requires that each state adopt and submit a SIP for the implementation, maintenance, and enforcement of each new or revised NAAQS promulgated by EPA. These SIPs are commonly referred to as ``infrastructure'' SIPs. The infrastructure requirements are designed to ensure that the structural components of each state's air quality management program are adequate to meet the state's responsibilities under the CAA.