225 ILCS 705/31.03

In every mine the minimum quantity of air shall not be less than 150 cubic feet per minute for each person employed, measured at the foot of the downcast and of the upcast. However, in any mine wherein explosive gas is being generated in such quantities that it can be detected by a multi-gas detector, the minimum quantity of air shall not be less than 200 cubic feet per minute for each person employed therein. The State Mine Inspector shall have power by order in writing to require these quantities to be increased.