What does 'MOD' stand for in Nitrox diving?

In Nitrox diving, 'MOD' stands for Maximum Operating Depth. This term indicates the deepest depth at which a diver can safely breathe a specific Nitrox mixture without risking toxicity from the oxygen content. Each gas mixture has a corresponding MOD, calculated based on the percentage of oxygen in the mix and the physiological effects of breathing oxygen under pressure.

As a diver descends, the partial pressure of oxygen increases, and if the partial pressure exceeds 1.4 ATA (atmospheres absolute), it can lead to oxygen toxicity, which is both dangerous and potentially life-threatening. Therefore, understanding and adhering to the MOD for a particular dive is crucial for maintaining safety while using Nitrox mixtures. This knowledge helps divers effectively plan their dives, ensuring they remain within safe limits to prevent oxygen toxicity and other related risks.