{"data":{"id":"us/40-cfr-52.51","jurisdiction":"us","citation":"40 CFR 52.51","heading":"Classification of regions.","body":"The Alabama plan was evaluated on the basis of the following classifications:\nAir quality control region Pollutant\nParticulate matter Sulfur oxides Nitrogen dioxide Carbon monoxide Photochemical oxidants (hydrocarbons)\nAlabama \u0026 Tombigbee Rivers Intrastate II III III III III\nColumbus (Georgia)-Phenix City (Alabama) Interstate I III III III III\nEast Alabama Intrastate I III III III III\nMetropolitan Birmingham Intrastate I II III I I\nMobile (Alabama)-Pensacola-Panama City (Florida)-Southern Mississippi Interstate I I III III I\nSoutheast Alabama Intrastate II III III III III\nTennessee River Valley (Alabama)-Cumberland Mountains (Tennessee) Interstate I I III III III","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER C—AIR PROGRAMS","PART 52—APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS","Subpart B—Alabama"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"377d52d0f26e5916c22174056eb024035b90cf709f562d9699e55d42efd8f9fb","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-52.50","next":"us/40-cfr-52.53"},"notice":"GroundRules: Original legal text. Not legal advice."}