40 CFR §63.9485

1. (a)You are subject to this subpart if you own or operate a friction materials manufacturing facility (as defined in § 63.9565) that is (or is part of) a major source of hazardous air pollutants (HAP) emissions. Your friction materials manufacturing facility is a major source of HAP if it emits or has the potential to emit any single HAP at a rate of 9.07 megagrams (10 tons) or more per year or any combination of HAP at a rate of 22.68 megagrams (25 tons) or more per year.
2. (b)The requirements in this subpart do not apply to research and development facilities, as defined in section 112(c)(7) of the Clean Air Act.