---
kind: "unit"
title: "40"
title_heading: "Protection of Environment"
key: "chI/subchC/part51"
level: "part"
label: "Part 51"
heading: "Requirements for Preparation, Adoption, and Submittal of Implementation Plans"
release: "ecfr-current"
date: "2026-08-27"
url: "https://uscodex.org/cfr/40/chI-subchC-part51"
sections_count: 203
---

# Part 51 — Requirements for Preparation, Adoption, and Submittal of Implementation Plans

Title 40 C.F.R. — Protection of Environment › Chapter I — Environmental Protection Agency › Subchapter C — Air Programs

## Contents

- [Subpart A — Air Emissions Reporting Requirements](/cfr/40/chI-subchC-part51-subpartA.md)
- [Subpart B-E — Subparts B-E [Reserved]](/cfr/40/chI-subchC-part51-subpartB-E.md)
- [Subpart F — Procedural Requirements](/cfr/40/chI-subchC-part51-subpartF.md)
- [Subpart G — Control Strategy](/cfr/40/chI-subchC-part51-subpartG.md)
- [Subpart H — Prevention of Air Pollution Emergency Episodes](/cfr/40/chI-subchC-part51-subpartH.md)
- [Subpart I — Review of New Sources and Modifications](/cfr/40/chI-subchC-part51-subpartI.md)
- [Subpart J — Ambient Air Quality Surveillance](/cfr/40/chI-subchC-part51-subpartJ.md)
- [Subpart K — Source Surveillance](/cfr/40/chI-subchC-part51-subpartK.md)
- [Subpart L — Legal Authority](/cfr/40/chI-subchC-part51-subpartL.md)
- [Subpart M — Intergovernmental Consultation](/cfr/40/chI-subchC-part51-subpartM.md)
- [Subpart N — Compliance Schedules](/cfr/40/chI-subchC-part51-subpartN.md)
- [Subpart O — Miscellaneous Plan Content Requirements](/cfr/40/chI-subchC-part51-subpartO.md)
- [Subpart P — Protection of Visibility](/cfr/40/chI-subchC-part51-subpartP.md)
- [Subpart Q — Reports](/cfr/40/chI-subchC-part51-subpartQ.md)
- [Subpart R — Extensions](/cfr/40/chI-subchC-part51-subpartR.md)
- [Subpart S — Inspection/Maintenance Program Requirements](/cfr/40/chI-subchC-part51-subpartS.md)
- [Subpart T — Conformity to State or Federal Implementation Plans of Transportation Plans, Programs, and Projects Developed, Funded or Approved Under Title 23 U.S.C. or the Federal Transit Laws](/cfr/40/chI-subchC-part51-subpartT.md)
- [Subpart U — Economic Incentive Programs](/cfr/40/chI-subchC-part51-subpartU.md)
- [Subpart W — Determining Conformity of General Federal Actions to State or Federal Implementation Plans](/cfr/40/chI-subchC-part51-subpartW.md)
- [Subpart X — Provisions for Implementation of 8-hour Ozone National Ambient Air Quality Standard](/cfr/40/chI-subchC-part51-subpartX.md)
- [Subpart Y — Mitigation Requirements](/cfr/40/chI-subchC-part51-subpartY.md)
- [Subpart Z — Provisions for Implementation of PM 2.5 National Ambient Air Quality Standards](/cfr/40/chI-subchC-part51-subpartZ.md)
- [Subpart AA — Provisions for Implementation of the 2008 Ozone National Ambient Air Quality Standards](/cfr/40/chI-subchC-part51-subpartAA.md)
- [Subpart BB — Data Requirements for Characterizing Air Quality for the Primary SO 2 NAAQS](/cfr/40/chI-subchC-part51-subpartBB.md)
- [Subpart CC — Provisions for Implementation of the 2015 Ozone National Ambient Air Quality Standards](/cfr/40/chI-subchC-part51-subpartCC.md)
- [Subpart DD — Requirements for Reclassified Ozone Nonattainment Areas](/cfr/40/chI-subchC-part51-subpartDD.md)