225 ILCS 705/31.19

All ventilating fans shall have suitable automatic devices attached to them for the purpose of sounding an alarm when the fan stops

Laws 1953, p. 701.

The alarm shall be placed so that it will be seen or heard by a responsible person.

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