What is the maximum partial pressure of oxygen (PO2) considered safe in Nitrox diving?

The maximum partial pressure of oxygen (PO2) considered safe in Nitrox diving is widely recognized to be 1.4 ATA. This guideline is essential for preventing the central nervous system toxicity associated with elevated oxygen levels. At 1.4 ATA, divers can safely utilize Nitrox blends for recreational dives without exceeding the acceptable limits that could lead to harmful physiological effects.

Maintaining a PO2 at or below this level is crucial during the descent and ascent phases of a dive, and it allows for extended bottom times while minimizing the risk of oxygen toxicity. Guidelines for various dive profiles and conditions often recommend 1.4 ATA as a conservative threshold to ensure safety while still allowing reasonable dive duration and depth.

Diving deeper or spending extended time at higher partial pressures, such as those indicated by the other options, significantly increases the risk of oxygen toxicity and is not advisable within recreational diving practices.