Versions of 40 CFR Part 52 - Approval and Promulgation of Implementation Plans on LawServer 2024 40 CFR Part 52 – Approval and Promulgation of Implementation Plans 2023 40 CFR PART 52 – APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS 2022 40 CFR Part 52 – Approval and Promulgation of Implementation Plans 2021 40 CFR Part 52 – Approval and Promulgation of Implementation Plans