What is the typical maximum percentage of oxygen in EANx mixtures used for recreational diving?

The typical maximum percentage of oxygen in enriched air nitrox (EANx) mixtures used for recreational diving is 40%. This concentration is popular among divers because it provides several benefits, including extended bottom time and reduced nitrogen absorption, which helps manage the risk of decompression sickness.

The use of a maximum oxygen percentage of 40% is essential because it balances the advantages of increased oxygen availability with the need to minimize exposure to higher levels of oxygen, which can lead to toxicity issues at greater depths. Knowing the appropriate limits is crucial for safe diving practices as divers must stay within these guidelines to maintain safe oxygen partial pressures throughout their dives, especially at greater depths.

While higher percentages of oxygen, such as those above 40%, may be used in specialized diving applications, they are not typically recommended for recreational divers due to the increased risk of oxygen toxicity and the required additional training and equipment that come with deeper or more complex dives.