What is the maximum ppO2 considered safe for diving?

The maximum partial pressure of oxygen (ppO2) considered safe for diving is typically accepted to be 1.4 bar. This limit is based on research and practice that indicate a ppO2 above this level can increase the risk of oxygen toxicity, particularly during exposure for longer durations.

Diving at a ppO2 of 1.4 bar allows for a safety buffer when managing the risks associated with oxygen exposure while still providing adequate oxygen for breathing and reducing the risk of hypoxia. For recreational diving, this level is often used, especially in Nitrox diving practices, where enriched air with higher oxygen content is a common choice.

Options that provide higher ppO2 values, such as 2.0 bar and 1.6 bar, are generally used in very controlled environments or specific technical diving scenarios but pose significant risks for toxicity at depths or times where the diver cannot monitor or control their exposure closely. The option of 0.8 bar is below the recommended operating limits for standard diving practices, meaning it wouldn’t provide sufficient oxygen levels needed for normal diving activities. The choice of 1.4 bar is derived from guidelines set by various diving organizations to enhance safety without sacrificing the benefits of enriched air.