Good ventilation is extremely important in underground mines. A well designed ventilation system can be used to control the temperature, quality of breathable air and in modern mines disperse radon gas. Air doors were used to prevent the passage of air through a mine working, in locations where access to the sealed area is still needed. Doors can be used to control the direction of the airflow through the mine.  They also can be used to seal off parts of the mine to make it easier to build up air pressure if using a pressurized ventilation system. These doors were often used in pairs to create airlocks. The doors in these cases would be separated with enough distance to fit a motor and train of cars inside the airlock.  Doors in high traffic areas where motors were used, had a compressed air opening system installed.  The Queen Tunnel originally had one of these style doors installed near the bottom of the stairs to the stope. This system had an air cylinder   mounted to the rib of the tunnel. Attached to the cylinder was a cable that went through some cable holders, a pulley then to the door.  When approaching a door, the cylinder was activated by moving a leaver. The leavers were located from 50ft. to 200ft. in advance of the door. The cylinder will down stroke pulling the cable causing the door to open. Today all that is left of the mechanism is 6” x 8’ timber bolted to the tunnel rib. This timber held the air cylinder, valve and cables used in it’s opening. Air doors of this style were used until the underground mines shut down in 1975.