Scuba diving is interesting to so many people. It seems so amazing to move freely under water and have some adventure. Scuba tanks are normally filled with compressed air. Air contains approximately 20% oxygen and 80% nitrogen. The trouble arises in deep sea diving.
Nitrogen gas dissolves in blood at high pressures. When divers dive deep into the sea, long-term inhalation of nitrogen can cause a feeling of euphoria, called nitrogen narcosis. The symptoms are similar to being drunk, including reduced concentration, trouble physical movements, and loss of dive control. Nitrogen narcosis in extreme levels can lead to unconsciousness.
If the divers rise too quickly to the surface, they will encounter a rapid decrease in pressure. The dissolved nitrogen will be rapidly released from blood, and formation of gas bubbles occurs. This illness is known as “the bends”, which can be severely hazardous for divers.
In the mid-1920s, Joel Henry Hildebrand introduced helium to replace nitrogen in scuba tanks. Helium has low solubility in blood. It is much lighter than nitrogen and released much faster from blood, decreasing the risk of getting “the bends”. Helium is an inert gas and safe to breathe. Since helium is non-toxic, it can be breathed for a long time without tissue damage. The helium concentration in a scuba tank depends on the depth the divers plan to go.