625 ILCS 5/13C-20
The Agency shall propose any other standards necessary to achieve reductions in the emission of hydrocarbons, carbon monoxide, and oxides of nitrogen from motor vehicles subject to inspection under this Chapter. Within 120 days after the Agency proposes those standards, the Board shall adopt any necessary rules establishing standards for the emission of hydrocarbons, carbon monoxide, and oxides of nitrogen from motor vehicles subject to inspection under this Chapter. The rules may be amended from time to time pursuant to Agency proposals. The Board shall set standards necessary to achieve the reductions in vehicle hydrocarbons, carbon monoxide, and oxides of nitrogen emissions, as determined by the applicable vehicle emission estimation model and rules developed by the United States Environmental Protection Agency, that are required by the federal Clean Air Act. A predetermined rate of failure shall not be used in determining standards necessary to achieve the reductions in vehicle hydrocarbons, carbon monoxide, and oxides of nitrogen emissions. The emission standards established by the Board for vehicles of model year 1981 or later shall be identical in substance, as defined in Section 7.2(a) of the Environmental Protection Act, to the emission standards promulgated by the United States Environmental Protection Agency.
Except as otherwise provided in this subsection, subsection (b) of Section 27 of the Environmental Protection Act and the rulemaking provisions of the Illinois Administrative Procedure Act do not apply to rules adopted by the Board under this subsection. Challenges to the validity of rules adopted by the Board under this subsection or subsection (a) of Section 13B-20 may be brought only by filing a petition for review in the Appellate Court under Section 29 of the Environmental Protection Act within 35 days after the rule is filed with the Secretary of State.
625 ILCS 5/13C-20