What is the maximum percentage of oxygen that sport divers are allowed to use in a Nitrox mixture?

In the context of Nitrox for sport divers, the maximum percentage of oxygen typically recommended is 40%. This limit is established to ensure safe diving practices while minimizing the risk of oxygen toxicity, which can occur at higher partial pressures of oxygen during dives.

A Nitrox mixture with an oxygen concentration of 40% is still within safe limits for recreational diving, allowing divers to benefit from reduced nitrogen levels, leading to longer times before the onset of nitrogen narcosis and a higher level of safety regarding decompression sickness.

Higher percentages of oxygen, such as 45% or more, can increase the risk of oxygen toxicity, particularly during deeper dives where the partial pressure of oxygen rises significantly. Therefore, adhering to a 40% maximum helps maintain a balance between enjoying the benefits of increased oxygen while mitigating potential risks.