225 ILCS 705/31.18

In all mines starting operation after July 1, 1947, the ventilating fan shall be installed on the surface in a fireproof building

Laws 1953, p. 701.

In all mines starting operation after July 1, 1947, the ventilating fan shall be installed on the surface in a fireproof building.

Official source: Illinois General Assembly. Reproduced from public-domain Illinois statutes; confirm against the official source for the current text. Not legal advice.