30 CFR 57.5039 - Maximum permissible concentration.

Regulations last checked for updates: Feb 11, 2026

Title 30 - Mineral Resources last revised: Jan 27, 2026

View all text of Subpart D [§ 57.5001 - § 57.5075]

§ 57.5039 - Maximum permissible concentration.

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.

authority: 30 U.S.C. 811.

source: 50 FR 4082, Jan. 29, 1985, unless otherwise noted.

cite as: 30 CFR 57.5039