New Source Review (NSR) Preconstruction Permitting

Current understanding

The Clean Air Act’s New Source Review (NSR) program requires major stationary sources and major modifications to obtain preconstruction air permits before beginning construction. Key definitions — including ‘begin actual construction’ and what counts as a ‘pollutant-emitting activity’ — determine which physical work can start before permit issuance, affecting project timelines and capital exposure. EPA has periodically revisited these definitions to clarify how much site preparation and non-emitting construction (e.g., foundations, ancillary buildings) may proceed pre-permit.

Evidence log

• 2026-07-07 — Minor New Source Review Program Air Permitting Public Participation Requirements for State Implementation Plans: 2025 — EPA proposed rule would allow state and local air agencies greater discretion to determine the level of public participation required in minor NSR permitting programs approved into SIPs, modifying existing Clean Air Act implementation requirements without altering the underlying permitting mechanism. (novelty: 2)

Open questions

Related