52.1121—Classification of regions.

The Massachusetts 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
Metropolitan Boston Intrastate	I	I	III	I	I
Merrimack Valley-Southern New Hampshire Interstate	I	I	III	III	III
Metropolitan Providence Interstate	I	I	III	III	III
Central Massachusetts Intrastate	I	II	III	III	III
Hartford-New Haven-Springfield Interstate	I	I	III	I	I
Berkshire Intrastate	II	III	III	III	III

Code of Federal Regulations

[37 FR 10872, May 31, 1972, as amended at 39 FR 16346, May 8, 1974; 45 FR 61303, Sept. 16, 1980]