30 CFR § 70.305
Respiratory equipment; gas, dusts, fumes, or mists.
Respiratory equipment approved by NIOSH under 42 CFR part 84 shall be
provided to persons exposed for short periods to inhalation hazards from gas,
dusts, fumes, or mist. When the exposure is for prolonged periods, other
measures to protect such persons or to reduce the hazard shall be taken.
For further information: See MSHA's Program Policy Manual
[ 60 FR 30341, June 8, 1995]