52.2021—Classification of regions.

The Pennsylvania plan was evaluated on the basis of the following classifications:

Air quality control region	Pollutant
Air quality control region	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

Code of Federal Regulations

[37 FR 10889, May 31, 1972, as amended at 39 FR 16347, May 8, 1974; 45 FR 33627, May 20, 1980]