What safety measure should divers take regarding oxygen levels during deep dives?

Maintaining the partial pressure of oxygen (ppO2) below 1.40 is essential for divers, particularly during deep dives. The reason this measure is crucial is that higher levels of oxygen can increase the risk of oxygen toxicity, which can lead to serious health risks such as convulsions, visual disturbances, and other neurological issues. The threshold of 1.40 ata (atmospheres absolute) is often regarded as a safe upper limit for diving, as it balances the need for adequate oxygen supply while minimizing the hazards associated with excessive oxygen exposure.

Monitoring and controlling the ppO2 ensures that divers can experience the benefits of increased oxygen availability without crossing into potentially dangerous territory. This safety measure is part of a broader strategy that includes proper dive planning, gas management, and adherence to dive tables or computers designed for the specific type of dive being undertaken. In contrast, increasing oxygen levels periodically, consuming more oxygen, or diving with minimal effort do not adequately address the critical need to manage partial pressure of oxygen within safe limits.