Virginia Code Title 45.2. Mines, Minerals, and Energy § 45.2-844. Ventilation with air from certain areas

Active face workings shall not be ventilated with air that has passed through a worked-out area or has been used to ventilate a pillar line. This section shall not apply to air that is being used to ventilate an active pillar line or a room that is necessary to establish and maintain such pillar line.