Mine safety in coal mines, which in turn can initiate more extensive coal dust explosions. For this reason, rock dusts such as limestone dust are spread throughout coal mines to diminish the chances of coal dust explosions as well as to limit the extent of potential explosions, in a process known as rock dusting. Coal dust explosions can also begin independently of methane gas explosions. Frictional heat and sparks generated by mining equipment can ignite both methane gas and coal dust. For this reason, water is often used to cool rock-cutting sites. Miners utilize equipment strong enough to break through extremely hard
Inert gas sources rich in this element, through cryogenic distillation or membrane separation. For specialized applications, purified inert gas may be produced by specialized generators on-site. They are often used aboard chemical tankers and product carriers (smaller vessels). Benchtop specialized generators are also available for laboratories. Because of the non-reactive properties of inert gases they are often useful to prevent undesirable chemical reactions from taking place. Food is packed in inert gas to remove oxygen gas. This prevents bacteria from growing. It also prevents chemical oxidation by oxygen in normal air. An example is the rancidification (caused by oxidation) of edible oils.