146. As of 1 April 1993, it is prohibited to install a diesel engine or boiler at a distance of less than:(1) 15 m (49.2 ft) from a surface opening of an underground mine used as an air exhaust;
(2) 25 m (82 ft) from a surface opening of an underground mine used as an air intake;
(3) 15 m (49.2 ft) from a building covering a surface opening of an underground mine.