40 CFR 51.1009 : 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) — Provisions For Implementation Of Pm2.5 National Ambient Air Quality Standards (§ 51.1000 To § 51.1012) — Reasonable further progress (RFP) requirements.