{"data":{"id":"us/40-cfr-52.171","jurisdiction":"us","citation":"40 CFR 52.171","heading":"Classification of regions.","body":"The Arkansas plan was evaluated on the basis of the following classifications:\nAir quality control region Pollutant\nParticulate matter Sulfur oxides Nitrogen dioxide Carbon monoxide Ozone\nCentral Arkansas Intrastate II III III III III\nMetropolitan Fort Smith Interstate II III III III III\nMetropolitan Memphis Interstate I III III III I\nMonroe (Louisiana)-El Dorado (Arkansas) Interstate II III III III III\nNortheast Arkansas Intrastate III III III III III\nNorthwest Arkansas Intrastate III III III III III\nShreveport-Texarkana-Tyler Interstate II 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 E—Arkansas"],"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":"75deacb3f9615c645d4e94c4d7d1b037f8fd8c51f8bf6f30724b948da8237dca","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-52.170","next":"us/40-cfr-52.172"},"notice":"GroundRules: Original legal text. Not legal advice."}