40 CFR § 52.1121 - Classification of regions.
---
identifier: "/us/cfr/t40/s52.1121"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 52.1121 - Classification of regions."
title_number: 40
title_name: "Protection of Environment"
section_number: "52.1121"
section_name: "Classification of regions."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "C"
subchapter_name: "AIR PROGRAMS"
part_number: "52"
part_name: "APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 7401"
cfr_part: "52"
---
# 52.1121 Classification of regions.
The Massachusetts plan was evaluated on the basis of the following classifications:
| | | | | | |
| --- | --- | --- | --- | --- | --- |
| 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 |
[37 FR 10872, May 31, 1972, as amended at 39 FR 16346, May 8, 1974; 45 FR 61303, Sept. 16, 1980; 84 FR 29383, June 24, 2019]