Labor Code - LAB
DIVISION 5. SAFETY IN EMPLOYMENT [6300 - 9254]
( Division 5 enacted by Stats. 1937, Ch. 90. ) PART 9. TUNNEL AND MINE SAFETY [7950 - 8004]
( Part 9 added by Stats. 1972, Ch. 1430. ) CHAPTER 2. Gassy and Extrahazardous Tunnels [7965 - 7985]
( Chapter 2 added by Stats. 1972, Ch. 1430. ) 7979.
In tunnels or underground mines classified extrahazardous, sufficient air shall be supplied to maintain an atmosphere of all of the following conditions:
(a) Not less than 19 percent oxygen.
(b) Not more than 0.5 percent carbon dioxide.
(c) Not more than 5 parts per million nitrogen dioxide.
(d) No petroleum vapors or other toxic gases in concentrations exceeding the threshold limit values established annually by the American Conference of Governmental Industrial Hygienists.
(Added by Stats. 1972, Ch. 1430.)