For at least 200 feet inside the mine portal or collar timber used for ground support in intake openings and in exhaust openings that are designated as escapeways shall be -
(a) Provided with a fire suppression system, other than fire extinguishers and water hoses, capable of controlling a fire in its early stages; or
(b) Covered with shotcrete, gunite, or other material with equivalent fire protection characteristics; or
(c) Coated with fire-retardant paint or other material to reduce its flame spread rating to 25 or less and maintained in that condition.
[50 FR 4082, Jan. 29, 1985, as amended at 50 FR 20100, May 14, 1985]