{"data":{"id":"us/40-cfr-52.2171","jurisdiction":"us","citation":"40 CFR 52.2171","heading":"Classification of regions.","body":"The South Dakota plan evaluated on the basis of the following classifications:\nAir quality control region Pollutant\nParticulate matter Sulfur oxides Nitrogen dioxide Carbon monoxide Photochemical oxidants (hydrocarbons)\nMetropolitan Sioux City Interstate III III III III III\nMetropolitan Sioux Falls Interstate II III III III III\nBlack Hills—Rapid City Intrastate III III III III III\nSouth Dakota 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 QQ—South Dakota"],"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":"3be281d4aa0226bc81bbf919c4f33d7c1304d5e8375c9093a4d4fe0249411644","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-52.2170","next":"us/40-cfr-52.2172"},"notice":"GroundRules: Original legal text. Not legal advice."}