30 CFR § 57.5044
Respirators.
In environments exceeding 1.0 WL, miners shall wear respirators approved
by NIOSH for radon daughters prior to July 10, 1995 or under the
equivalent section of 42 CFR part 84 and such respirator use shall be in
compliance with §57.5005.
[60 FR 30398, June 8, 1995]