42 U.S.C. § 7472
(a) Areas designated as class I Upon the enactment of this part, all—
and which are in existence on , shall be class I areas and may not be redesignated. All areas which were redesignated as class I under regulations promulgated before , shall be class I areas which may be redesignated as provided in this part. The extent of the areas designated as Class I under this section shall conform to any changes in the boundaries of such areas which have occurred subsequent to , or which may occur subsequent to .
(July 14, 1955, ch. 360, title I, § 162, as added Pub. L. 95–95, title I, § 127(a), , 91 Stat. 731; amended Pub. L. 95–190, § 14(a)(40), , 91 Stat. 1401; Pub. L. 101–549, title I, §§ 108(m), 110(2), , 104 Stat. 2469, 2470.)
1990—Subsec. (a). Pub. L. 101–549, § 108(m), inserted at end “The extent of the areas designated as Class I under this section shall conform to any changes in the boundaries of such areas which have occurred subsequent to , or which may occur subsequent to .”
Subsec. (b). Pub. L. 101–549, § 110(2), substituted “designated pursuant to section 7407(d) of this title as attainment or unclassifiable” for “identified pursuant to section 7407(d)(1)(D) or (E) of this title”.
1977—Subsec. (a)(4). Pub. L. 95–190 inserted a comma after “size”.