40 CFR § 52.04 - Classification of regions.
---
identifier: "/us/cfr/t40/s52.04"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 52.04 - Classification of regions."
title_number: 40
title_name: "Protection of Environment"
section_number: "52.04"
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"
---
# 52.04 Classification of regions.
Each subpart sets forth the priority classification, by pollutant, for each region in the State. Each plan for each region was evaluated according to the requirements of part 51 of this chapter applicable to regions of that priority.