{"data":{"id":"us/40-cfr-52.821","jurisdiction":"us","citation":"40 CFR 52.821","heading":"Classification of regions.","body":"The Iowa plan was evaluated on the basis of the following classification:\nAir quality control region Pollutant\nParticulate matter Sulfur oxides Nitrogen dioxide Carbon monoxide Photochemical oxidants (hydrocarbons)\nMetropolitan Omaha-Council Bluffs Interstate I II III III III\nMetropolitan Sioux Falls Interstate II III III III III\nMetropolitan Sioux City Interstate III III III III III\nMetropolitan Dubuque Interstate I III III III III\nMetropolitan Quad Cities Interstate I III III III III\nBurlington-Keokuk Interstate I I III III III\nNorthwest Iowa Intrastate III III III III III\nNorth Central Iowa Intrastate IA III III III III\nNortheast Iowa Intrastate I III III III III\nSouthwest Iowa Intrastate III III III III III\nSouth Central Iowa Intrastate I III III III I\nSoutheast Iowa 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 Q—Iowa"],"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":"03d4a6174da34e1fff348291cfb13cd96d56a11cadb27397902993ef0c647c29","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-52.820","next":"us/40-cfr-52.822"},"notice":"GroundRules: Original legal text. Not legal advice."}