Flying and diving
Depending on the diving depths and time spent underwater, inert gases are liable to remain in and saturate a diver’s body and body tissue for an extended period of time. The inert gas used when diving is nitrogen.
During controlled ascent, and drops in surrounding pressure, the gas is slowly released. This is called de-saturation and it does not cease immediately upon surfacing. Depending on diving conditions (time, depth, number of consecutive dives, etc) complete de-saturation may continue for a number of hours after ascent.
During the period needed for complete de-saturation, flying is an additional risk. Due to sudden drops in cabin pressure, from atmospheric to normal cabin pressure (c. 0.75 bar), signs of decompression sickness may be noticed. Sudden cabin decompression may be an additional problem.
In order to fly safely, the NO-FLY interval should be observed, i.e. the time it takes for the body to release the critical quantity of nitrogen.