30 C.F.R. § 57.5039 Maximum permissible concentration.
Title 30 - Mineral Resources
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.
Title 30: Mineral Resources
PART 57—SAFETY AND HEALTH STANDARDS—UNDERGROUND METAL AND NONMETAL MINES
Subpart D—Air Quality, Radiation, Physical Agents, and Diesel Particulate Matter
Radiation—Underground Only
§ 57.5039 Maximum permissible concentration.
