(225 ILCS 705/5.22)
(from Ch. 96 1/2, par. 522)
Where coal is broken down "on shift"; and while men are in the
mine, with compressed air, or by some mechanical or chemical-mechanical
device which does not emit spark or flame, he shall see that frequent
examination for gas and other hazards is made by competent personnel.
(Source: Laws 1953, p. 701.)