225 ILCS 710/37
It shall be the duty of every operator of every mine, except as hereinafter provided, to maintain at least 2 outlets to the surface from such mine, or an under-ground communicating passageway between every such mine and some other neighboring mine, so that there shall be at all times at least 2 distinct and available means of access to the surface to all persons employed in such mine. Such outlets shall not be less than 100 feet apart and there shall be between them a space not less than 50 feet in width free of buildings or inflammable structures or material. Provided, however, should unusual conditions be encountered in any mine which, in the opinion of the Inspector, makes compliance with this Section impossible for the time being written permission may be granted by the Department of Natural Resources to continue operating only for the limited period of time necessary and for the purpose only of relieving, overcoming, or removing such conditions which prevent compliance.
Where 2 openings to the surface shall not have been provided as aforesaid, it shall be the duty of the Inspector to order in writing, served upon the operator or superintendent of such mine, a second opening to be made without delay by the operator of said mine and in the event of the operator of such mine failing forthwith to commence and prosecute the making of a second opening within 20 days after the service of said order, or in the event of the Inspector deeming any mine having only one such opening to be dangerous to the lives and health of those employed therein. The Inspector is hereby empowered to order work stopped in any part of the mine, or in the entire mine and to order the immediate withdrawal of any and all employees from the danger area. The Inspector shall then immediately notify the Department of Natural Resources of the situation and it may institute an action for an injunction to close said mine as provided for in Section 10 of this Act.
Provided, however, that as to all mines which are in operation on the effective date of this amendment, the above requirements shall not apply in case of (a) shafts or mines in process of being connected, to comply with the terms of this Section; (b) shafts, winzes, adits, levels, tunnels, and drifts to prospect for and develop mineral substances, but not for the extraction of mineral substances, except such as may be extracted in the course of such prospecting and development work; (c) any mine in which one of the shafts or outlets shall have temporarily become unavailable for the persons employed in the mine, and in which every effort is being made by the operator in the mine to open such temporarily unavailable outlet, and provided the same is not, in the opinion of the Inspector dangerous to life and health of those employed therein; (d) mines having workings less than 100 feet deep and extending less than 500 feet from the shaft in any direction, but not mines opened primarily by an adit, level, or tunnel; and (e) mines opened by an adit, level, tunnel, or drift less than 1,000 feet in length; and provided further, that mines opened by an inclined shaft if less than 20 angle from the horizontal shall be considered for the purpose of this Section and Act as equivalent to a mine opened by an adit, level, tunnel, or drift.
Provided, further, that any prospecting or development property opened by a timbered shaft and exempt under exception (b) from providing two outlets to the surface shall not permit more than 50 people to work underground at any one time, unless such shafts be provided with a water sprinkling system.
225 ILCS 710/37