When might a diver need to switch from Nitrox to regular air?

A diver may need to switch from Nitrox to regular air if equipment fails or if the depth exceeds the mix’s Maximum Operating Depth (MOD). This situation is critical because each specific Nitrox blend has a set MOD based on its oxygen content, which is determined to prevent oxygen toxicity as depth increases. If a diver descends beyond this depth limit, the partial pressure of oxygen in the mix can become dangerously high, potentially leading to serious health risks. In the event of equipment failure—such as issues with the Nitrox tank or regulator—it may be necessary to switch to normal air to ensure a safe return to the surface. This transition helps maintain safe breathing gas composition and overall diver safety in situations where the risks associated with Nitrox cannot be managed.