Missouri Revised Statutes Title XVIII. Labor and Industrial Relations § 293.210. Shaft coal mines, ventilation requirements

1. The owner, agent or operator of every coal mine, whether operated by shaft, slope or drift, shall provide and maintain for every such mine a good and sufficient amount of ventilation for such men as may be employed therein, the amount of air in circulation to be in no case less than one hundred cubic feet for each man per minute, measured at the foot of the downcast, and the same to be increased at the discretion of the director of the division according to the character and extent of the workings, or to the amount of powder used in blasting and said volume of air shall be forced and circulated to the face of every working place throughout the mine, so that such mine shall be free from standing powder smoke and gases of every kind.

2. All doors set on main entries for the purpose of conducting the ventilation shall be so constructed and hung as to close of themselves when opened, and shall be made sufficiently tight to effectually obstruct the air currents. In all mines employing fifty or more men a trapper shall be kept in attendance upon such doors to see that they are kept securely closed and the air currents properly controlled.

3. Whenever the director shall find men working without sufficient air, or under any unsafe conditions, he shall first give the operator a reasonable notice to rectify the same, and upon his refusal to do so, may himself order them out until said portions of said mine shall be put in proper condition.

4. The ventilation required by this section may be produced by any suitable appliances, but in case a furnace shall be used for ventilating purposes, it shall be built in such a manner as to prevent the communication of fire to any part of the works, by lining the upcast with incombustible material for a sufficient distance up from said furnace.

5. The currents of air in coal mines shall be so split as to give a separate current to at least every fifty men at work, and the director shall have discretion to order a separate current for a smaller number of men, if special conditions render it necessary.