40 C.F.R. § 52.2021 — Classification of regions.
§ 52.2021 Classification of regions. The Pennsylvania plan was evaluated on the basis of the following classifications: Air quality control region Pollutant Particulate matter Sulfur oxides Nitrogen dioxide Carbon monoxide Ozone (hydrocarbons) Metropolitan Philadelphia Interstate I I III I I Northeast Pennsylvania-Upper Delaware Valley Interstate I II III III III South Central Pennsylvania Intrastate I II III III III Central Pennsylvania Intrastate I III III III III Southwest Pennsylvania Intrastate I I III I I Northwest Pennsylvania-Youngstown Interstate I II III III III [37 FR 10889, May 31, 1972, as amended at 39 FR 16347, May 8, 1974; 45 FR 33627, May 20, 1980]