The quantity of air reaching the last open crosscut in any pair or set of entries shall not be less than 9,000 cubic feet a minute, except that the quantity of air reaching the last open crosscut in any pair or set of entries in pillar sections may be less than 9,000 cubic feet a minute if not less than 9,000 cubic feet of air a minute is being delivered to the intake end of the pillar line. No work shall be performed in any area that does not meet this standard except to correct this violation. In robbing areas where the air currents cannot be controlled and measurements of the air cannot be obtained, the air shall have perceptible movement.
225 ILCS 705/31.02