104 STAT. 2520 PUBLIC LAW 101-549—NOV. 15, 1990 combined emissions of oxides of nitrogen (NO,) and nonmethane hydrocarbons (NMHC) shall not exceed 3.15 grams per brake horsepower hour (equivalent to 50 percent of the combined emission standards applicable under section 202 for such air pollutants in the Case of a conventional model year 1994 heavy-duty diesel-fueled vehicle or engine). No standard shall be promulgated as provided in this section for any heavy-duty vehicle of more than 26,000 lbs. GVWR. " (b) REVISED STANDARDS THAT ARE LESS STRINGENT.— (1) The Administrator may promulgate a revised less stringent standard for the vehicles or engines referred to in subsection (a) if the Administrator determines that the 50 percent reduction required under subsection (a) is not technologically feasible for clean diesel-fueled vehicles and engines, taking into account durability, costs, lead time, safety, and other relevant factors. To provide adequate lead time the Administrator shall make a determination with regard to the technological feasibility of such 50 percent reduction before December 31, 1993. "(2) Any person may at any time petition the Administrator to make a determination under paragraph (1). The Administrator shall act on such a petition within 6 months after the petition is filed. "(3) Any revised less stringent standards promulgated as provided in this subsection shall require at least a 30 percent reduction in lieu of the 50 percent reduction referred to in paragraph (1). 42 USC 7586. "SEC. 246. CENTRALLY FUELED FLEETS "(a) FLEET PROGRAM REQUIRED FOR CERTAIN NONATTAINMENT AREAS.— "(1) SIP REVISION.— Each State in which there is located all or part of a covered area (as defined in paragraph (2)) shall submit, within 42 months after the enactment of the Clean Air Act Amendments of 1990, a State implementation plan revision under section 110 and part D of title I to establish a clean-fuel vehicle program for fleets under this section. "(2) COVERED AREAS. —For purposes of this subsection, each of the following shall be a 'covered area': "(A) OZONE NONATTAINMENT AREAS. — Any ozone nonattainment area with a 1980 population of 250,000 or more classified under subpart 2 of part D of title I of this Act as Serious, Severe, or Extreme based on data for the calendar years 1987, 1988, and 1989. In determining the ozone nonattainment areas to be treated as covered areas pursuant to this subparagraph, the Administrator shall use the most recent interpretation methodology issued by the Administrator prior to the enactment of the Clean Air Act Amendments of 1990. " (B) CARBON MONOXIDE NONATTAINMENT AREAS. — Any carbon monoxide nonattainment area with a 1980 population of 250,000 or more and a carbon monoxide design value at or above 16.0 parts per million based on data for calendar years 1988 and 1989 (as calculated according to the most recent interpretation methodology issued prior to enactment of the Clean Air Act Amendments of 1990 by the United States Environmental Protection Agency), excluding those carbon monoxide nonattainment areas in which mobile sources do not contribute significantly to carbon monoxide exceedances.
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