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.
RCW 49.24.110
Exhaust valves.
1973 1st ex.s. c 154 s 90; 1941 c 194 s 4; Rem
Official source: Washington State Legislature. Reproduced from public-domain Washington statutes; confirm against the official source for the current text. Not legal advice.