What is the maximum partial pressure of oxygen (PPO2) recommended for recreational diving?

The recommended maximum partial pressure of oxygen (PPO2) for recreational diving is 1.4 ATA (atmospheres absolute). This value is considered a safe threshold to minimize the risk of oxygen toxicity while still allowing divers to benefit from using enriched air mixtures.

At a PPO2 of 1.4 ATA, divers can effectively utilize enhanced oxygen levels provided by nitrox without exposing themselves to higher risks that occur at greater PPO2 levels. Oxygen toxicity can result in serious health issues, such as central nervous system toxicity, which can provoke symptoms like seizures while diving. Keeping the PPO2 at or below 1.4 ATA helps to mitigate these risks, providing a balance between safety and the advantages of increased oxygen in the breathing mix.

While some divers may use mixtures that have higher PPO2 levels when conducting specific types of work or exploration dives, for general recreational diving, the 1.4 ATA limit is the widely accepted guideline to promote diver safety and health.