{"data":{"id":"us/40-cfr-52.1171","jurisdiction":"us","citation":"40 CFR 52.1171","heading":"Classification of regions.","body":"The Michigan plan was evaluated on the basis of the following classifications:\nAir quality control region Pollutant\nParticulate matter Sulfur oxides Nitrogen dioxide Carbon monoxide Ozone\nMetropolitan Detroit-Port Huron Intrastate I I III III III\nMetropolitan Toledo Interstate I I III III I\nSouth Central Michigan Intrastate II II III III III\nSouth Bend-Elkhart (Indiana)-Benton Harbor (Michigan) Interstate I IA III III III\nCentral Michigan Intrastate II III III III III\nUpper Michigan 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 X—Michigan"],"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":"889c800333d421071686d03a8b695717bfd6c023adffe789dda1fa340e7743c2","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-52.1170","next":"us/40-cfr-52.1172"},"notice":"GroundRules: Original legal text. Not legal advice."}