---
kind: "unit"
title: "40"
title_heading: "Protection of Environment"
key: "chI/subchC/part51/subpartBB"
level: "subpart"
label: "Subpart BB"
heading: "Data Requirements for Characterizing Air Quality for the Primary SO 2 NAAQS"
release: "ecfr-current"
date: "2026-08-27"
url: "https://uscodex.org/cfr/40/chI-subchC-part51-subpartBB"
sections_count: 6
---

# Subpart BB — Data Requirements for Characterizing Air Quality for the Primary SO 2 NAAQS

Title 40 C.F.R. — Protection of Environment › Chapter I — Environmental Protection Agency › Subchapter C — Air Programs › Part 51 — Requirements for Preparation, Adoption, and Submittal of Implementation Plans

## Sections

- [§51.1200. Definitions.](/cfr/40/51.1200.md)
- [§51.1201. Purpose.](/cfr/40/51.1201.md)
- [§51.1202. Applicability.](/cfr/40/51.1202.md)
- [§51.1203. Air agency requirements.](/cfr/40/51.1203.md)
- [§51.1204. Enforceable emission limits providing for attainment.](/cfr/40/51.1204.md)
- [§51.1205. Ongoing data requirements.](/cfr/40/51.1205.md)