StacksVerified U.S. regulatory reference

Part 81 — Designation of Areas for Air Quality Planning Purposes

Subpart A — Meaning of Terms

Subpart B — Designation of Air Quality Control Regions

Subpart C — Section 107 Attainment Status Designations

Subpart D — Identification of Mandatory Class I Federal Areas Where Visibility Is an Important Value

Subpart E — Identification of Interstate Transport Regions