Okla. Stat. tit. 45, § 45-442: Use of engines not meeting standards prohibited

It shall be unlawful to use or to order or permit the use of any

diesel engine in any lead, zinc or other metal mine in this state at

any time which is not equipped with detoxification equipment and

other safety devices meeting the standards set forth in the rules

and recommendations promulgated by the U.S. Bureau of Mines, or when

such detoxification equipment and other safety devices on the engine

is defective, or not in perfect working order.