The Environmental Protection Agency (EPA) is taking final action to approve a revision to the State Implementation Plan (SIP) for the State of Missouri. This final action will amend a Missouri regulation that controls emissions from facilities in St. Louis City and Jefferson, St. Charles, Franklin, and St. Louis Counties. The revisions to this rule include amending the rule applicability section for sources subject to the rule, removing unnecessary words, updating incorporations by reference, amending definitions specific to the rule, updating test and reference methods and other minor edits. These revisions meet the requirements of the Clean Air Act (CAA) and do not impact the stringency of the SIP or air quality. Approval of these revisions will ensure consistency between State and federally approved rules.