The Environmental Protection Agency (EPA) is proposing to approve revisions to the Missouri State Implementation Plan (SIP) received on February 11, 2020. In the submission, Missouri requests to revise a regulation related to reporting of start-up, shutdown, and malfunction (SSM) events. The revisions to this rule include adding incorporations by reference to other State rules, including definitions specific to the rule and making administrative wording changes. These revisions do not impact the stringency of the SIP or air quality. Approval of these revisions will ensure consistency between State and federally approved rules.