What is the maximum oxygen percentage typically used in recreational diving with nitrox?

In recreational diving, the maximum oxygen percentage typically used in nitrox mixtures is up to 40%. This percentage is widely accepted because it provides a balance between increasing the allowable bottom time and reducing the risk of nitrogen narcosis and decompression sickness compared to air.

Diving with a nitrox mixture that contains 40% oxygen allows divers to take advantage of the reduced nitrogen content, which is beneficial for longer dives and shorter surface intervals. However, it's critical to understand that while increasing the oxygen percentage can enhance bottom time, it also raises the risk of oxygen toxicity at depth. Therefore, divers using nitrox must be aware of their maximum operating depth (MOD) based on the oxygen exposure limits set for recreational divers.

The other options listed, such as 32%, 36%, and 42%, refer to combinations of nitrogen and oxygen that are either lower than the maximum used frequently or exceed the generally accepted limits for recreational diving practices.