The Environmental Protection Agency (EPA) is taking final action to approve revisions to the Missouri State Implementation Plan (SIP) received on November 29, 2016, and March 7, 2019. The revisions were submitted by Missouri in response to a finding of substantial inadequacy and SIP call published on June 12, 2015, for a provision in the Missouri SIP related to excess emissions during startup, shutdown, and malfunction (SSM) events. In the submissions, Missouri requests to revise a regulation related to restriction of emissions of visible air contaminants. The revisions to the rule include removing a statement from the compliance and performance testing provisions that does not meet Clean Air Act (CAA) requirements, adding exemptions for emission units regulated by stricter federal and state regulations or that do not have the capability of exceeding the emission limits of the rule, adding an alternative test method and making other administrative changes. Approval of these revisions will ensure consistency between state and federally approved rules.