30 CFR § 57.22235 Actions at 1.0 percent methane (I-C, II-A, II-B, and IV mines).
(a) If methane reaches 1.0 percent in the mine atmoshpere, all
persons other than competent persons necessary to make ventilation changes
shall be withdrawn from affected areas until methane is reduced to less than
0.5 percent.
(b) If methane reaches 1.0 percent at a work place and there has been
a failure of the main ventilation system, all persons shall be withdrawn from
the mine.
