{"data":{"id":"us/40-cfr-52.471","jurisdiction":"us","citation":"40 CFR 52.471","heading":"Classification of regions.","body":"The District of Columbia plan was evaluated on the basis of the following classifications:\nAir quality control region Pollutant\nParticulate matter Sulfur oxides Nitrogen dioxide Carbon monoxide Ozone\nNational Capital Interstate I I III I I","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER C—AIR PROGRAMS","PART 52—APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS","Subpart J—District of Columbia"],"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":"b2f5e2972625b1320f8d5359a8514cfa11c972888cfbcc28cf0a8e0698d93308","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-52.470","next":"us/40-cfr-52.472"},"notice":"GroundRules: Original legal text. Not legal advice."}