Subpart effective Aug. 7, 1977, except as otherwise expressly provided, see section 406(d) of Pub. L. 95–95, set out as an Effective Date of 1977 Amendment note under section 7401 of this title.

Section 127(c) of Pub. L. 95–95 required Administrator, not later than 1 year after Aug. 7, 1977, to publish a guidance document to assist States in carrying out their functions under part C of title I of the Clean Air Act (this part) with respect to pollutants for which national ambient air quality standards are promulgated.

Section 127(d) of Pub. L. 95–95 directed Administrator, not later than 2 years after Aug. 7, 1977, to complete a study and report to Congress on progress made in carrying out part C of title I of the Clean Air Act (this part) and the problems associated in carrying out such section.