225 ILCS 710/39
It shall be unlawful for the operator of any mine after the passage of this Act to erect any combustible structure over the shaft, tunnel or other mine opening, except headframes necessary for hoisting from such shaft or other mine opening, and the hatch or door necessary for closing such shaft or other mine opening. Provided, however, that a housing of noninflammable and fireproof material may be erected over any shaft, tunnel or other mine opening to protect the people working at such point.
It shall be the duty of every operator to provide every adit, tunnel, inclined shaft, or slope of less than 20 angle from the horizontal, the mouth of which is covered by a building or house of any kind, with a door near the mouth of such adit, tunnel, inclined shaft, or slope of less than 20 angle from the horizontal that can be closed from outside of the building by a pull-wire or cable in the event of fire.
In every timbered mine in which more than 100 people are employed underground there shall be in each drift or other working leading from any shaft used as a manway, a metal or metal-covered door suitably hung at a place in the drift or other working not more than 75 feet distant from the shaft from which such working leads. Such doors shall be so set that when closed they may be quickly made airtight, and for the purpose of sealing them there shall be kept in close proximity to each door a suitable quantity of moist earth or moist clay. Such door must swing inward toward the shaft and no such door shall be fitted with any catch that will prevent its being readily pushed open by a person from the other side.
225 ILCS 710/39