Okla. Stat. tit. 45, § 45-520: Inspection for gas

In all mines wherein explosive gas is generated, and also in all

mines where the fire damp has generated, in sufficient quantities to

be detected by the ordinary safety lamp, every working place without

exception, and all roadways shall be carefully examined immediately

before each shift by a competent person, who shall be known as the

fireboss, appointed by the superintendent and mine foreman for that

purpose. The person or persons making such examination shall use no

light other than that enclosed in a safety lamp while making such

examination. In all cases, said examination shall be begun within

the shortest possible period of time necessary to complete such

inspection before the regular time appointed to commence work, but

in no case shall said examination be begun more than three (3) hours

prior to the appointed time of each shift in commencing work, and it

shall be the duty of the said fire boss to examine for all dangers

likely to be found, and after each examination to leave at the face

and sides of every place so examined, evidence of his presence, and

he shall at each examination, inspect the entrance, or entrances, to

the worked out or abandoned parts, which are adjacent to the

roadways and working places of the mines where fire damp is likely

to accumulate, and in every working place and all other places where

explosive gas is discovered, also where immediate danger is found to

exist from other causes he shall place a danger signal across the

entrance to such places, which shall be a sufficient warning for all

persons not to enter said place.