{"data":{"id":"us/30-cfr-57.5039","jurisdiction":"us","citation":"30 CFR 57.5039","heading":"Maximum permissible concentration.","body":"Except as provided by standard § 57.5005, persons shall not be exposed to air containing concentrations of radon daughters exceeding 1.0 WL in active workings.","path":["Title 30—Mineral Resources","CHAPTER I—MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR","SUBCHAPTER K—METAL AND NONMETAL MINE SAFETY AND HEALTH","PART 57—SAFETY AND HEALTH STANDARDS—UNDERGROUND METAL AND NONMETAL MINES","Subpart D—Air Quality, Radiation, Physical Agents, and Diesel Particulate Matter"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-30.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:25:24Z","sha256":"dec2adc7e718314fb572c4c5f8c3f0ac972c8ff3f4e30651e945cdf3a0559e6b","source_id":"us-cfr","stale":true,"prev":"us/30-cfr-57.5038","next":"us/30-cfr-57.5040"},"notice":"GroundRules: Original legal text. Not legal advice."}