 Any substitution may introduce counter-diffusion complications, owing to differing rates of diffusion of the inert gases, which can lead to a net gain in total dissolved gas tension in a tissue.This can lead to bubble formation and growth, with decompression sickness as a consequence.Partial pressure of oxygen is usually limited to 1.6 bar during in water decompression for scuba divers, but can be up to 1.9 bar in-water and 2.2 bar in the chamber when using the US Navy tables for surface decompression, and up to 2.8 bar for therapeutic decompression.