40 CFR § 52.671 - Classification of regions.
---
identifier: "/us/cfr/t40/s52.671"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 52.671 - Classification of regions."
title_number: 40
title_name: "Protection of Environment"
section_number: "52.671"
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"
---
# 52.671 Classification of regions.
The Idaho plan was evaluated on the basis of the following classifications:
| | | | | | |
| --- | --- | --- | --- | --- | --- |
| Eastern Idaho Intrastate | I | II | III | III | III. |
| Eastern Washington Northern Idaho Interstate (Idaho) | I | II | III | III | III. |
| Idaho Intrastate | I | III | III | III | III. |
| Metropolitan Boise Intrastate | II | III | III | I | III. |
[37 FR 10861, May 31, 1972, as amended at 45 FR 70261, Oct. 23, 1980; 47 FR 32534, July 28, 1982]