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.
225 ILCS 705/24.03
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.
225 ILCS 705/24.03