30 CFR Part 57Public Domain
§ 57.5039 — Maximum permissible concentration
Subpart D — Air Quality, Radiation, Physical Agents, and Diesel Particulate Matter
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.
Public Domain: 30 CFR Part 57 (MSHA Safety and Health Standards — Underground Metal and Nonmetal Mines) is a U.S. government publication and is not subject to copyright. Text extracted from the official source ↗. Figures are served from the eCFR; if one does not load, use the link in its place.