52.421—Classification of regions.

The Delaware 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	Photochemical oxidants (hydrocarbons)
Metropolitan Philadelphia Interstate	I	I	III	I	I
Southern Delaware Intrastate	III	III	III	III	III

Code of Federal Regulations

[37 FR 10856, May 31, 1972, as amended at 39 FR 16345, May 8, 1974]