40 CFR 52.1121: Classification of regions.

The Massachusetts 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 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