What does the term 'off-gas' refer to in Nitrox diving?

The term 'off-gas' in Nitrox diving specifically refers to the elimination of dissolved gases from the body as a diver ascends. During a dive, nitrogen is absorbed into the body's tissues due to increased pressure underwater. As the diver ascends and pressure decreases, this nitrogen can become supersaturated in the tissues, and it must be safely off-gassed to avoid complications such as decompression sickness.

When divers ascend, the decrease in ambient pressure allows these dissolved gases to be released back into the bloodstream and expelled through respiration. This is a critical aspect of safely managing nitrogen levels in the body and is essential for preventing the formation of nitrogen bubbles, which can lead to serious injury or illness. Understanding the off-gassing process is fundamental for safe dive practices, especially when using Nitrox mixes that can alter the absorption and off-gassing rates of nitrogen compared to air.