What is considered a safe PO2 for deep dives (greater than 40 meters)?

When considering safe partial pressures of oxygen (PO2) for deep dives, particularly those exceeding 40 meters, a partial pressure of 1.2 ATA is typically regarded as a threshold that balances safety and efficiency in utilizing oxygen while minimizing the risk of oxygen toxicity.

Breathing oxygen at higher partial pressures increases the risk of central nervous system (CNS) oxygen toxicity. While 1.4 ATA is accepted as a maximum for certain scenarios, it is often recommended to stay at or below 1.2 ATA during deeper dives to provide an additional safety margin. This approach allows divers to benefit from the advantages of enriched air nitrox while reducing the risks associated with deeper dives.

Exceeding this level, such as reaching a partial pressure of 1.6 ATA or higher, could significantly increase the likelihood of experiencing adverse effects. Therefore, 1.2 ATA is recognized as a prudent choice for ensuring safety in the context of deep diving operations, reflecting a balance between available oxygen and safety considerations.