This final action addresses the agency's residual risk and technology review (RTR) of the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Friction Materials Manufacturing Facilities. The Friction Materials Manufacturing Facilities NESHAP, subpart QQQQQ, was promulgated pursuant to section 112(d) of the Clean Air Act (CAA) on October 18, 2002. 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 solvent mixers. The HAP emitted from solvent mixers include n-hexane and methanol. 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). CAA 112(f)(2) directs EPA to revise the NESHAP if such revisions 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. 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, EPA completed this action on December 20, 2018, and it was published in the Federal Register on February 8, 2019 (84 FR 2742).