(a) In implementing the requirements of section 109 of the Clean Air Act,¹ the board may adopt, by regulation, only those control measures or other requirements which are reasonably required, in accordance with the Clean Air Act deadlines, to achieve and maintain the ambient air quality standards or to satisfy related Clean Air Act requirements, unless otherwise specifically authorized or required by this act or specifically required by the Clean Air Act.

(b) Control measures or other requirements adopted under subsection (a) of this section shall be no more stringent than those required by the Clean Air Act unless authorized or required by this act or specifically required by the Clean Air Act. This requirement shall not apply if the board determines that it is reasonably necessary for a control measure or other requirement to exceed minimum Clean Air Act requirements in order for the Commonwealth:

(c) The board may not by regulation adopt an ambient air quality standard for a specific pollutant which is more stringent than the air quality standard which the EPA has adopted for the specific pollutant pursuant to section 109 of the Clean Air Act.

(d) In any challenge to the enforcement of regulations adopted to achieve and maintain the ambient air quality standards or to satisfy related Clean Air Act requirements, the person challenging the regulation shall have the burden to demonstrate that the control measure or other requirement or the stringency of the control measure or requirement is not reasonably required to achieve or maintain the standard or to satisfy related Clean Air Act requirements.

(e) No person may file a preenforcement review challenge under this section based in any manner upon the standards set forth in subsection (b) of this section.

(f) This section shall not apply to rules and regulations approved as a final rulemaking by the board prior to the effective date of this section or to any ambient air quality standards adopted by the board where no such standard has been adopted by the EPA.

(g) This section shall not be construed to weaken or otherwise affect site-specific standards or other requirements for individual sources or facilities in place prior to the effective date of this section.