BlackletterCalifornia law

Labor Code § 7979

CHAPTER 2. Gassy and Extrahazardous Tunnels

Current as of September 28, 2026Lab. Code, § 7979Official source ↗

Added by Stats. 1972, Ch. 1430.

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.