§ 57.22233 Actions at 0.5 percent methane (I-C mines).
If methane reaches 0.5 percent in the mine atmosphere, ventilation changes shall be made to reduce the level of methane. Until methane is reduced to less than 0.5 percent, no other work shall be permitted in affected areas.
[52 FR 24941, July 1, 1987; 52 FR 27903, July 24, 1987]