Exhaust valves.
Exhaust valves shall be provided, having risers extending to the upper part of chamber, if necessary, and shall be operated at such times as may be required and especially after a blast, and persons shall not be required to resume work after a blast until the gas and smoke have cleared, for at least thirty minutes.
NOTES:
Severability—1973 1st ex.s. c 154: See note following RCW
2.12.030.