30 CFR § 75.401
Abatement of dust; water or water with a wetting agent.
[STATUTORY PROVISION]
Where underground mining operations in active workings create or raise
excessive amounts of dust, water or water with a wetting agent added to it,
or other no less effective methods approved by the Secretary or his
authorized representative, shall be used to abate such dust. In working
places, particularly in distances less than 40 feet from the face, water,
with or without a wetting agent, or other no less effective methods approved
by the Secretary or his authorized representative, shall be applied to coal
dust on the ribs, roof, and floor to reduce dispersibility and to minimize
the explosion hazard.