Section 52.422 - Approval status(a) With the exceptions set forth in this subpart, the Administrator approves Delaware's plan for the attainment and maintenance of the national standards under section 110 of the Clean Air Act. Furthermore, the Administrator finds that the plan satisfies all requirements of part D, title 1, of the Clean Air Act as amended in 1977.(b) Letter of February 26, 1993, from the Delaware Department of Natural Resources and Environmental Control transmitting a commitment to adopt either the Federal clean fuel fleet program or an alternative substitute program by May 15, 1994.45 FR 14558, Mar. 6, 1980, as amended at 58 FR 50848, Sept. 29, 1993; 78 FR 33984 , June 6, 2013