Because of the way the Buhlmann decompression algorithm table shows the way inert gases such as nitrogen and helium enter and leave the body, they can be used by divers to plan the depth and duration of their dives.
The Buhlmann decompression algorithm is a mathematical model (algorithm) of the way in which inert gases enter and leave the human body as the ambient pressure changes. These decompression tables allow divers to plan the depth and duration for dives and the required decompression stops. Purified argon and nitrogen gases are most commonly used as inert gases due to their high natural abundance (78.3% N2, 1% Ar in air) and low relative cost. The group 18 elements include helium, neon, argon, krypton, xenon and radon. They are referred to as noble gases or inert gases. 
