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Title 40

Displaying title 40, up to date as of 6/09/2026. Title 40 was last amended 6/08/2026.
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Title 40Protection of EnvironmentPart / Section
Chapter IEnvironmental Protection Agency1 – 1099
Subchapter CAir Programs50 – 99
Part 51Requirements for Preparation, Adoption, and Submittal of Implementation Plans51.1 – 51.1403
Subpart AAir Emissions Reporting Requirements51.1 – 51.50
Subparts B-E [Reserved]
Subpart FProcedural Requirements51.100 – 51.105
Subpart GControl Strategy51.110 – 51.126
Subpart HPrevention of Air Pollution Emergency Episodes51.150 – 51.153
Subpart IReview of New Sources and Modifications51.160 – 51.166
Subpart JAmbient Air Quality Surveillance51.190
Subpart KSource Surveillance51.210 – 51.214
Subpart LLegal Authority51.230 – 51.232
Subpart MIntergovernmental Consultation51.240 – 51.242
Subpart NCompliance Schedules51.260 – 51.262
Subpart OMiscellaneous Plan Content Requirements51.280 – 51.286
Subpart PProtection of Visibility51.300 – 51.309
Subpart QReports51.320 – 51.328
Subpart RExtensions51.341
Subpart SInspection/Maintenance Program Requirements51.350 – 51.373
Subpart TConformity 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 Laws51.390
Subpart UEconomic Incentive Programs51.490 – 51.494
Subpart WDetermining Conformity of General Federal Actions to State or Federal Implementation Plans51.850 – 51.860
Subpart XProvisions for Implementation of 8-hour Ozone National Ambient Air Quality Standard51.900 – 51.919
Subpart YMitigation Requirements51.930
Subpart ZProvisions for Implementation of PM2.5 National Ambient Air Quality Standards51.1000 – 51.1016
Subpart AAProvisions for Implementation of the 2008 Ozone National Ambient Air Quality Standards51.1100 – 51.1119
Subpart BBData Requirements for Characterizing Air Quality for the Primary SO2 NAAQS51.1200 – 51.1205
Subpart CCProvisions for Implementation of the 2015 Ozone National Ambient Air Quality Standards51.1300 – 51.1319
Subpart DD-Requirements for Reclassified Ozone Nonattainment Areas51.1400 – 51.1403
Appendixes A-K to Part 51 [Reserved]
Appendix L to Part 51
Example Regulations for Prevention of Air Pollution Emergency Episodes
Appendix M to Part 51
Recommended Test Methods for State Implementation Plans
Appendixes N-O to Part 51 [Reserved]
Appendix P to Part 51
Minimum Emission Monitoring Requirements
Appendixes Q-R to Part 51 [Reserved]
Appendix S to Part 51
Emission Offset Interpretative Ruling
Appendixes T-U to Part 51 [Reserved]
Appendix V to Part 51
Criteria for Determining the Completeness of Plan Submissions
Appendix W to Part 51
Guideline on Air Quality Models
Appendix X to Part 51
Examples of Economic Incentive Programs
Appendix Y to Part 51
Guidelines for BART Determinations Under the Regional Haze Rule