Active face workings shall not be ventilated with air that has passed through worked-out areas or has been used to ventilate pillar lines. This section shall not apply to air which is being used to ventilate an active pillar line and rooms which are necessary to establish and maintain the pillar line.
Code 1950, § 45-60.5; 1954, c. 191; 1966, c. 594, § 45.1-62; 1993, c. 442; 1994, c. 28; 1996, c. 774; 1999, c. 256.