{"data":{"id":"us/40-cfr-52.921","jurisdiction":"us","citation":"40 CFR 52.921","heading":"Classification of regions.","body":"The Kentucky 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)\nAppalachian Intrastate II III III III III\nBluegrass Intrastate II III III III III\nEvansville (Indiana)-Owensboro-Henderson (Kentucky) Interstate I II III III III\nHuntington (West Virginia)-Ashland (Kentucky)-Portsmouth-Ironton (Ohio) Interstate I III III III III\nLouisville Interstate I I III III I\nMetropolitan Cincinnati Interstate I II III III I\nNorth Central Kentucky Intrastate II III III III III\nPaducah (Kentucky)-Cairo (Illinois) Interstate I II III III III\nSouth Central Kentucky Intrastate III III 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 S—Kentucky"],"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":"ae18ee11c227315b4b33e34d2c58f6fa765e73636b884c865e9f3e62656a33d3","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-52.920","next":"us/40-cfr-52.922"},"notice":"GroundRules: Original legal text. Not legal advice."}