The Administrator shall issue guidance documents under section 7408 of this title for purposes of assisting States in implementing requirements of this part respecting the lowest achievable emission rate. Such a document shall be published not later than nine months after August 7, 1977, and shall be revised at least every two years thereafter.
(July 14, 1955, ch. 360, title I, § 178, as added Pub. L. 95–95, title I, § 129(b), Aug. 7, 1977, 91 Stat. 750.)