40 CFR § 52.2471 - Classification of regions.
---
identifier: "/us/cfr/t40/s52.2471"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 52.2471 - Classification of regions."
title_number: 40
title_name: "Protection of Environment"
section_number: "52.2471"
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"
---
# 52.2471 Classification of regions.
The Washington plan was evaluated on the basis of the following classifications:
| | | | | | |
| --- | --- | --- | --- | --- | --- |
| Eastern Washington-Northern Idaho Interstate | I | IA | III | III | III |
| Northern Washington Intrastate | II | III | III | III | III |
| Olympic-Northwest Washington Intrastate | II | II | III | III | III |
| Portland Interstate | I | IA | III | III | III |
| Puget Sound Intrastate | I | IA | III | III | I |
| South Central Washington Intrastate | I | III | III | III | III |
[81 FR 1131, Jan. 11, 2016]