--- kind: "section" citation: "42 U.S.C. § 7549" title: "42" title_heading: "The Public Health and Welfare" number: "7549" heading: "High altitude performance adjustments" release: "119-102" date: "2026-07-12" url: "https://uscodex.org/usc/42/7549" units: - "Chapter 85 — Air Pollution Prevention and Control" - "Subchapter II — Emission Standards for Moving Sources" - "Part A — Motor Vehicle Emission and Fuel Standards" --- # §7549. High altitude performance adjustments - (a) **Instruction of the manufacturer—** - (1) Any action taken with respect to any element of design installed on or in a [motor vehicle](/usc/42/7550.md?p=2) or [motor vehicle](/usc/42/7550.md?p=2) engine in compliance with regulations under this subchapter (including any alteration or adjustment of such element), shall be treated as not in [violation](/usc/42/2000e–16a.md?p=c) of [section 7522(a) of this title](/usc/42/7522.md?p=a) if such action is performed in accordance with high altitude adjustment instructions provided by the [manufacturer](/usc/42/7550.md?p=1) under [subsection (b)](#b) and approved by the [Administrator](/usc/42/7602.md?p=a). - (2) If the [Administrator](/usc/42/7602.md?p=a) finds that adjustments or [modifications](/usc/42/7501.md?p=4) made pursuant to instructions of the [manufacturer](/usc/42/7550.md?p=1) under [paragraph (1)](#a-1) will not insure emission control performance with respect to each standard under [section 7521 of this title](/usc/42/7521.md) at least equivalent to that which would result if no such adjustments or [modifications](/usc/42/7501.md?p=4) 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](/usc/42/7501.md?p=4) as may be necessary to insure emission control performance at different altitudes shall be submitted by the [manufacturer](/usc/42/7550.md?p=1) to the [Administrator](/usc/42/7602.md?p=a) pursuant to regulations promulgated by the [Administrator](/usc/42/7602.md?p=a). - (2) Any knowing [violation](/usc/42/2000e–16a.md?p=c) by a [manufacturer](/usc/42/7550.md?p=1) of requirements of the [Administrator](/usc/42/7602.md?p=a) under [paragraph (1)](#b-1) shall be treated as a [violation](/usc/42/2000e–16a.md?p=c) by such [manufacturer](/usc/42/7550.md?p=1) of [section 7522(a)(3) of this title](/usc/42/7522.md?p=a-3) for purposes of the penalties contained in [section 7524 of this title](/usc/42/7524.md). - (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 parts—** No instructions under this section respecting adjustments or [modifications](/usc/42/7501.md?p=4) may require the use of any [manufacturer](/usc/42/7550.md?p=1) parts (as defined in [section 7522(a) of this title](/usc/42/7522.md?p=a)) unless the [manufacturer](/usc/42/7550.md?p=1) demonstrates to the satisfaction of the [Administrator](/usc/42/7602.md?p=a) that the use of such [manufacturer](/usc/42/7550.md?p=1) parts is necessary to insure emission control performance. - (d) **State inspection and maintenance programs—** Before January 1, 1981 the authority provided by this section shall be available in any high altitude [State](/usc/42/7602.md?p=d) (as determined under regulations of the [Administrator](/usc/42/7602.md?p=a) under regulations promulgated before August 7, 1977) but after December 31, 1980, such authority shall be available only in any such [State](/usc/42/7602.md?p=d) in which an inspection and maintenance program for the testing of [motor vehicle](/usc/42/7550.md?p=2) emissions has been instituted for the portions of the [State](/usc/42/7602.md?p=d) where any national ambient air quality standard for auto-related pollutants has not been attained. - (e) **High altitude testing—** - (1) The [Administrator](/usc/42/7602.md?p=a) 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](/usc/42/7521.md?p=d)), each class or category of vehicle and engines to which regulations under [section 7521 of this title](/usc/42/7521.md) 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](/usc/42/7602.md?p=a) in effect as of November 15, 1990. - (2) The [Administrator](/usc/42/7602.md?p=a), in cooperation with the [Secretary](/usc/42/242q–4.md?p=2) of Energy and the [Administrator](/usc/42/7602.md?p=a) of the Federal Transit Administration, and such other [agencies](/usc/42/8262.md?p=1) as the [Administrator](/usc/42/7602.md?p=a) 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](/usc/42/7602.md?p=a) 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](/usc/42/7602.md?p=a) 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 credit (July 14, 1955, ch. 360, title II, § 215, as added Pub. L. 95–95, title II, § 211(b), Aug. 7, 1977, 91 Stat. 757; amended Pub. L. 95–190, § 14(a)(75), Nov. 16, 1977, 91 Stat. 1404; Pub. L. 101–549, title II, § 224, Nov. 15, 1990, 104 Stat. 2503; Pub. L. 102–240, title III, § 3004(b), Dec. 18, 1991, 105 Stat. 2088.) ## Notes ### Editorial Notes ### Codification In subsec. (d), “August 7, 1977” substituted for “the date of enactment of this Act” to reflect the probable intent of Congress that such date of enactment meant the date of enactment of Pub. L. 95–95. ### Amendments 1990—Subsec. (e). Pub. L. 101–549 added subsec. (e). 1977—Subsec. (d). Pub. L. 95–190 substituted “December 31, 1980” for “December 31, 1981”. ### Statutory Notes and Related Subsidiaries ### Change of Name “Federal Transit Administration” substituted for “Urban Mass Transportation Administration” in subsec. (e)(2) pursuant to section 3004(b) of Pub. L. 102–240, set out as a note under section 107 of Title 49, Transportation. ### Effective Date Section 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.