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
Noble gas After the risks caused by the flammability of hydrogen became apparent, it was replaced with helium in blimps and balloons. "Noble gas" is translated from the German noun , first used in 1898 by Hugo Erdmann to indicate their extremely low level of reactivity. The name makes an analogy to the term "noble metals", which also have low reactivity. The noble gases have also been referred to as "inert gases", but this label is deprecated as many noble gas compounds are now known. "Rare gases" is another term that was used, but this is also inaccurate because argon forms a