Section 7525 of title 42, referred to in par. (4), was in the original “section 206 of the Clean Air Act (42 U.S.C. 1857f–5)”, meaning act July 14, 1955, ch. 360, § 206, as added Dec. 31, 1970, Pub. L. 91–604, § 8(a), 84 Stat. 1694, which was formerly classified to section 1857f–5 of Title 42, The Public Health and Welfare, and which is classified to section 7525 of Title 42 pursuant to the general revision of the Clean Air Act by Pub. L. 95–95, Aug. 7, 1977, 91 Stat. 685.