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 adding incorporations by reference to other State rules, including definitions specific to the rule, removing unnecessary words, making other administrative wording changes, and adding alternative test methods.