What is the main factor affecting the maximum operating depth for a Nitrox mix?

The maximum operating depth for a Nitrox mix is primarily influenced by the percentage of oxygen in that mix. As the concentration of oxygen increases, the partial pressure of oxygen also increases with depth. This is critical because higher partial pressures can lead to increased risk of oxygen toxicity, especially above certain depths.

For example, a common guideline is that no more than 1.4 ATA (atmospheres absolute) of partial pressure of oxygen should be maintained during a dive, meaning the maximum operating depth must be calculated based on the oxygen content in the gas mix and the depth of the dive. For instance, if a diver is using a Nitrox mix with a high percentage of oxygen, their maximum operating depth will be shallower than for a mix with lower oxygen content.

Factors like water temperature, diver experience, and time underwater do play significant roles in overall dive safety and planning, but they do not directly determine the maximum depth at which a given Nitrox mix can be safely used. Instead, it is the oxygen content that directly impacts the physiological effects on the diver at depth.