The Clean Air Act (CAA) requires EPA to list and establish emission limits for categories of major sources and area sources of hazardous air pollutants (HAP) under CAA section 112(c). CAA section 112(c)(9) requires EPA to consider petitions to add or remove source categories. On August 28, 2019, EPA received a petition to remove the Stationary Combustion Turbines source category from the list of categories of major sources. On November 19, 2019, December 2, 2020,and February 16, 2021, EPA received supplements to the petition. The EPA is currently evaluating the petition. Once EPA has evaluated the petition, the Agency will determine whether the petition will be granted or denied. The EPA will notify the petitioners and the public of its determination.