This action addresses the agency's residual risk and technology review (RTR) of the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Taconite Iron Ore Processing. The Taconite Iron Ore Processing NESHAP, subpart RRRRR, was promulgated pursuant to section 112(d) of the Clean Air Act (CAA) on 10/30/03 (68 FR 61867). The NESHAP established emission limitations and/or work practice requirements based on maximum achievable control technology (MACT) for controlling emissions of hazardous air pollutants (HAP) from new and existing ore crushing and handling operations, indurating furnaces, finished pellet handling operations and ore dryers. The HAP emitted from these sources include metal hazardous air pollutants (e.g., arsenic, nickel, mercury, manganese and lead), acid gases (i.e., hydrogen chloride and hydrogen fluoride) and formaldehyde and other combustion-related gases. This action implements the residual risk review requirements of CAA section 112(f)(2) and the technology review requirements of CAA section 112(d)(6). The statute directs the EPA to promulgate emission standards under CAA 112(f)(2) if such standards are required to provide an ample margin of safety to protect public health or to prevent, taking relevant factors into account, an adverse environmental effect. Any such standards are to be promulgated within 8 years after promulgation of MACT standards under CAA section 112(d). CAA section 112(d)(6) requires the EPA to review and revise the MACT standards as necessary, taking into account developments in practices, processes and control technologies, no less often than every 8 years. Pursuant to a court order (Blue Ridge Environmental Defense League v. Pruitt, Case No: 1:16-cv-00364 (D.D.C. 2017)) related to the review of 13 source categories, EPA completed seven final RTR actions by December 31, 2018, and the agency was required to complete six additional RTR actions by June 30, 2020. This final action was signed on June 17, 2020, and published in the Federal Register on July 28, 2020 (85 FR 45476).