Section 7971 Of Chapter 2. Gassy And Extrahazardous Tunnels From California Labor Code >> Division 5. >> Part 9. >> Chapter 2.

. Whenever there is any ignition of gas or vapor in a tunnel or underground mine, all work shall cease, employees shall be removed, and reentry except for rescue purposes shall be prohibited until the division has conducted an inspection and authorized reentry for maintenance or production in writing.