A trained rescue crew of at least five men shall be provided at underground mines with more than 25 men or tunnels with 10 or more men underground at any one time. Smaller mines shall have one man for each 10 men underground who receives annual training in the use of breathing apparatus. Two trained crews shall be provided at mines with more than 50 men underground and at tunnels with more than 25 men underground.
(Added by Stats. 1972, Ch. 1430.)