The National Emission Standards for Hazardous Air Pollutants for the Polyether Polyols Production Industry (PEPO NESHAP), codified at 40 CFR part 63, subpart PPP, regulates hazardous air pollutant (HAP) emissions from the production of polyether polyols. On March 27, 2014, the EPA promulgated regulatory provisions for the PEPO NESHAP establishing that owners and operators may assert an affirmative defense to civil penalties for violations caused by malfunctions. On April 18, 2014, the D.C. Circuit Court issued an opinion vacating the portion of EPA’s Portland Cement Manufacturing Industry NESHAP that first established an affirmative defense (NRDC v. EPA, 749 F.3d 1055). The court found that the EPA lacked authority to establish an affirmative defense for private civil suits and held that, under the Clean Air Act, the authority to determine civil penalty amounts in such cases lies exclusively with the courts, not the EPA. In light of NRDC, EPA has been removing such provisions from all NESHAPs that contain an affirmative defense. This action will finalize removal of the affirmative defense provisions from the PEPO NESHAP.