Air shafts are open spaces that are created for the purpose of allowing ventilation into an enclosed space. Some examples of air shafts are simply holes that are bored from an underground operation to the surface, thus ensuring a steady supply of fresh air into the cave or other underground area. In various types of buildings, the air shaft is usually housed in the walls and may be used as a conduit to distribute heated or cooled air throughout the interior space.
The establishment of an air shaft is extremely important to any type of mining operation that requires humans to actually go underground, such as in a coal mine. Usually, an air shaft is drilled into the tunnel, creating a vertical connection with the surface. Fresh air from the surface is able to flow into the tunnel, making it much easier for workers to breathe. It is not unusual for several air shafts to be drilled along the length of a single tunnel, thus ensuring a continual flow of fresh air.
When used as part of the design for an aboveground structure, the air shaft is a simple design that makes it possible to control the flow of air throughout the space. Often, the shaft is included in the original plans for the building, effectively creating a network that connects with each room by way of a vent in the floor, ceiling or wall. One end of the shaft is often connected with a furnace or some type of heating and cooling equipment, making it possible to control the indoor temperature, as well as make sure that the air is constantly freshened throughout the space.
While many air shafts are relatively small in design, others are large enough for a person of average size to crawl through if necessary. This is sometimes the case in large mining operations, and serves the practical purpose of providing some type of escape route in the event of a collapse of one section of the mine tunnel. Assuming the air shaft is large enough, anyone trapped in that section can climb up the shaft and eventually reach ground level.
Alternatively, the strategic placement of shafts at different points along the tunnel also make it possible for fresh air to fill an area, even if a cave in has cut off access to the mine entrance. The air flow provided by the shaft increases the chances for survival, and often can buy precious time as rescue operations are initiated to free workers trapped in the tunnel.