Section 72.610 - Abrasive blasting(a)Surface and underground mines. When an abrasive blasting operation is performed, all exposed miners shall properly use respirators approved for abrasive blasting by NIOSH under 42 CFR part 84 , or the operation shall be performed in a totally enclosed device with the miner outside the device.(b)Underground areas of underground mines. Silica sand or other materials containing more than 1 percent free silica shall not be used as an abrasive substance in abrasive blasting.59 FR 8327, Feb. 18, 1994, as amended at 60 FR 30401, June 8, 1995