40 C.F.R. § 52.1021
Classification of regions.
Cite as 40 C.F.R. § 52.1021 (2026)
The Maine plan was evaluated on the basis of the following classifications: Air quality control region Pollutant Particulate matter Sulfur oxides Nitrogen dioxide Carbon monoxide Ozone Metropolitan Portland Intrastate I II III III III Androscoggin Valley Interstate IA IA III III III Down East Intrastate IA IA III III III Aroostook Intrastate III III III III III Northwest Maine Intrastate III III III III III [37 FR 10870, May 31, 1972, as amended at 45 FR 10774, Feb. 19, 1980]