Underground mine ventilation provides a flow of air to the underground workings of a mine of sufficient volume to dilute and remove noxious gases (typically NOx, SO2, methane, CO2 and CO). The source of these gases are equipment that runs on diesel engines, blasting with explosives,  and the orebody itself.  The largest component of the operating cost for mine ventilation is electricity to power the ventilation fans, which may account for one third of a typical underground mine’s entire electrical power cost.
Ventilation includes both the exchange of air to the outside as well as circulation of air within the mine. It is one of the most important factors for maintaining acceptable air quality in mines.