40 CFR 51.390 : Protection Of Environment (§ 1.1 To Parts 1851-1899) — (§ 50.1 To Appendix Y To Part 51) — Environmental Protection Agency (Continued) (§ 50.1 To Appendix Y To Part 51) — Air Programs (§ 50.1 To Appendix Y To Part 51) — Requirements For Preparation, Adoption, And Submittal Of Implementation Plans (§ 51.1 To Appendix Y To Part 51) — 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 (§ 51.390) — Implementation plan revision.