104 STAT. 2502 PUBLIC LAW 101-549—NOV. 15, 1990 whether an unreasonable risk exists, the Administrator shall consider factors including those described in section 202(a)(4)(B). "(d) ENFORCEMENT.—The standards under this section shall be subject to sections 206, 207, 208, and 209, with such modifications of the applicable regulations implementing such sections as the Administrator deems appropriate, and shall be enforced in the same Regulations. manner as standards prescribed under section 202. The Administrator shall revise or promulgate regulations as may be necessary to determine compliance with, and enforce, standards in effect under this section.". (b) STATE STANDARDS. —Section 209 of the Clean Air Act (42 U.S.C. 7543) is amended by adding the following at the end thereof: " (e) NONROAD ENGINES OR VEHICLES.— "(1) PROHIBITION ON CERTAIN STATE STANDARDS.— No State or any political subdivision thereof shall adopt or attempt to enforce any standard or other requirement relating to the control of emissions from either of the following new nonroad engines or nonroad vehicles subject to regulation under this Act— "(A) New engines which are used in construction equipment or vehicles or used in farm equipment or vehicles and which are smaller than 175 horsepower. "(B) New locomotives or new engines used in locomotives. Subsection (h) shall not apply for purposes of this paragraph. California. "(2) OTHER NONROAD ENGINES OR VEHICLES. —(A) In the case of any nonroad vehicles or engines other than those referred to in subparagraph (A) or (B) of paragraph (1), the Administrator shall, after notice and opportunity for public hearing, authorize California to adopt and enforce standards and other requirements relating to the control of emissions from such vehicles or engines if California determines that California standards will be, in the aggregate, at least as protective of public health and welfare as applicable Federal standards. No such authorization shall be granted if the Administrator finds that— "(i) the determination of California is arbitrary and capricious, "(ii) California does not need such California standards to meet compelling and extraordinary conditions, or "(iii) California standards and accompanying enforcement procedures are not consistent with this section. "(B) Any State other than California which has plan provisions approved under part D of title I may adopt and enforce, after notice to the Administrator, for any period, standards relating to control of emissions from nonroad vehicles or engines (other than those referred to in subparagraph (A) or (B) of paragraph (1)) and take such other actions as are referred to in subparagraph (A) of this paragraph respecting such vehicles or engines if— "(i) such standards and implementation and enforcement are identical, for the period concerned, to the California standards authorized by the Administrator under subparagraph (A), and "(ii) California and such State adopt such standards at least 2 years before commencement of the period for which the standards take effect. Regulations. The Administrator shall issue regulations to implement this subsection.".