The use of PPE (personal protective equipment) Blast-activated cut-off switches on machinery and electrical circuits (for example, in the form of a paddle that is activated by the blast) The use of overpressure-rated ventilation devices, of sufficient rating that they won't be destroyed by a windblast In hard-rock mines, harm minimisation may involve physically separating the cave (the void) from the working area by leaving an adequate thickness of muck-pile, and ensuring no other physical linkages exist between the cave and the working areas Providing dedicated leakage paths from the cave to atmosphere.