EPA is approving two State Implementation Plan revisions submitted by the State of Wyoming on September 11, 2008. Wyoming has revised its Air Quality Standards and Regulations, specifically Chapter 1, Section 5, Unavoidable equipment malfunction, and Chapter 1, Section 6, Credible evidence. Because these revisions conform to the Clean Air Act and EPA regulations, EPA is approving the revisions with the intention of making them Federally enforceable. EPA is taking this action under section 110 of the Clean Air Act.