High altitude performance adjustments
42 U.S.C. § 7549
in effect(a) Instruction of the manufacturer(1) Any action taken with respect to any element of design installed on or in a motor vehicle or motor vehicle engine in compliance with regulations under this subchapter (including any alteration or adjustment of such element), shall be treated as not in violation of section 7522(a) of this title if such action is performed in accordance with high altitude adjustment instructions provided by the manufacturer under subsection (b) and approved by the Administrator. (2) If the Administrator finds that adjustments or modifications made pursuant to instructions of the manufacturer under paragraph (1) will not insure emission control performance with respect to each standard under section 7521 of this title at least equivalent to that which would result if no such adjustments or modifications were made, he shall disapprove such instructions. Such finding shall be based upon minimum engineering evaluations consistent with good engineering practice.
(b) Regulations(1) Instructions respecting each class or category of vehicles or engines to which this subchapter applies providing for such vehicle and engine adjustments and modifications as may be necessary to insure emission control performance at different altitudes shall be submitted by the manufacturer to the Administrator pursuant to regulations promulgated by the Administrator. (2) Any knowing violation by a manufacturer of requirements of the Administrator under paragraph (1) shall be treated as a violation by such manufacturer of section 7522(a)(3) of this title for purposes of the penalties contained in section 7524 of this title. (3) Such instructions shall provide, in addition to other adjustments, for adjustments for vehicles moving from high altitude areas to low altitude areas after the initial registration of such vehicles.
(c) Manufacturer partsNo instructions under this section respecting adjustments or modifications may require the use of any manufacturer parts (as defined in section 7522(a) of this title) unless the manufacturer demonstrates to the satisfaction of the Administrator that the use of such manufacturer parts is necessary to insure emission control performance.
(d) State inspection and maintenance programsBefore January 1, 1981 the authority provided by this section shall be available in any high altitude State (as determined under regulations of the Administrator under regulations promulgated before August 7, 1977) but after December 31, 1980, such authority shall be available only in any such State in which an inspection and maintenance program for the testing of motor vehicle emissions has been instituted for the portions of the State where any national ambient air quality standard for auto-related pollutants has not been attained.
(e) High altitude testing(1) The Administrator shall promptly establish at least one testing center (in addition to the testing centers existing on November 15, 1990) located at a site that represents high altitude conditions, to ascertain in a reasonable manner whether, when in actual use throughout their useful life (as determined under section 7521(d) of this title), each class or category of vehicle and engines to which regulations under section 7521 of this title apply conforms to the emissions standards established by such regulations. For purposes of this subsection, the term “high altitude conditions” refers to high altitude as defined in regulations of the Administrator in effect as of November 15, 1990. (2) The Administrator, in cooperation with the Secretary of Energy and the Administrator of the Federal Transit Administration, and such other agencies as the Administrator deems appropriate, shall establish a research and technology assessment center to provide for the development and evaluation of less-polluting heavy-duty engines and fuels for use in buses, heavy-duty trucks, and non-road engines and vehicles, which shall be located at a high-altitude site that represents high-altitude conditions. In establishing and funding such a center, the Administrator shall give preference to proposals which provide for local cost-sharing of facilities and recovery of costs of operation through utilization of such facility for the purposes of this section. (3) The Administrator shall designate at least one center at high-altitude conditions to provide research on after-market emission components, dual-fueled vehicles and conversion kits, the effects of tampering on emissions equipment, testing of alternate fuels and conversion kits, and the development of curricula, training courses, and materials to maximize the effectiveness of inspection and maintenance programs as they relate to promoting effective control of vehicle emissions at high-altitude elevations. Preference shall be given to existing vehicle emissions testing and research centers that have established reputations for vehicle emissions research and development and training, and that possess in-house Federal Test Procedure capacity.
Source: OLRC USLMURL: https://uscode.house.gov/download/releasepoints/us/pl/119/95/xml_usc42@119-95.zipFetched: 6/7/2026