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 |