(225 ILCS 705/24.03) (from Ch. 96 1/2, par. 2403)
Sec. 24.03.
All underground mines, except those mines or areas of mines in which the dust is too wet or too high in incombustible content to propagate an explosion, shall be rock-dusted to within 40 feet of all faces.
(Source: Laws 1955, p. 2012.)