This action addresses amendments to the Portland Cement Manufacturing National Emission Standards for Hazardous Air Pollutants (NESHAP) (Portland Cement NESHAP), 40 CFR part 63, subpart LLL. The Portland Cement NESHAP was promulgated pursuant to section 112(d) of the Clean Air Act (CAA) on June 14, 1999. The residual risk and technology review (RTR) was promulgated pursuant to CAA 112(f) and 112(d)(6) on July 25, 2018. The NESHAP established emission limitations and work practice requirements based on maximum achievable control technology for control of hazardous air pollutants (HAP) from kilns at new and existing portland cement manufacturing plants. The pollutants emitted from portland cement manufacturing kilns include metallic HAP, hydrogen chloride, dioxin/furans, and mercury. This action addresses comments submitted to EPA by Sierra Club and two community groups in a petition for reconsideration of the 2018 final rule, submitted on September 21, 2018. In addition, EPA will address potentially unregulated pollutants in accordance with the D.C. Circuit’s opinion in Louisiana Environmental Action Network v. EPA, 955 F.3d 1088 (D.C. Cir. 2020) (“LEAN”). There is no court-ordered deadline associated with this action.