What is the maximum percentage of oxygen allowed in a Nitrox mixture for sport divers?

The maximum percentage of oxygen allowed in a Nitrox mixture for sport divers is EAN40, which contains 40% oxygen. This level is significant because it is widely accepted for recreational diving within the sport diving community. EAN40 is commonly recommended for dives up to 30 meters (100 feet) in depth, balancing the benefits of increased oxygen in the mix—such as reduced nitrogen absorption and extended bottom times—without exceeding safety limits regarding oxygen toxicity.

Oxygen levels above 40% can pose greater risks, such as oxygen toxicity, especially in deeper dives where partial pressures of oxygen can become dangerously high. Therefore, EAN40 is designated as a standard maximum for sport divers, ensuring a safer diving experience while still providing the advantages of using enriched air.