40 CFR § 51.153 - Reevaluation of episode plans.

---
identifier: "/us/cfr/t40/s51.153"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 51.153 - Reevaluation of episode plans."
title_number: 40
title_name: "Protection of Environment"
section_number: "51.153"
section_name: "Reevaluation of episode plans."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "C"
subchapter_name: "AIR PROGRAMS"
part_number: "51"
part_name: "REQUIREMENTS FOR PREPARATION, ADOPTION, AND SUBMITTAL OF IMPLEMENTATION PLANS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "23 U.S.C. 101; 42 U.S.C. 7401-7671q."
regulatory_source: "36 FR 22398, Nov. 25, 1971, unless otherwise noted."
cfr_part: "51"
---


# 51.153 Reevaluation of episode plans.

(a) States should periodically reevaluate priority classifications of all Regions or portion of Regions within their borders. The reevaluation must consider the three most recent years of air quality data. If the evaluation indicates a change to a higher priority classification, appropriate changes in the episode plan must be made as expeditiously as practicable.

(b) [Reserved]