At what ppO2 level is the threshold for CNS oxygen toxicity considered to be?

The threshold for CNS (central nervous system) oxygen toxicity is considered to be at a partial pressure of oxygen (ppO2) level of 1.4 bar. At this level, the risk of experiencing symptoms of CNS oxygen toxicity increases, which can include seizures and other neurological effects. It's important for divers using enriched air nitrox to understand this threshold because maintaining a ppO2 below this level helps mitigate the risks associated with oxygen toxicity while diving.

At 1.4 bar, the oxygen concentration in the diving mix can still provide significant benefits for longer dives and deeper profiles without crossing into the range where toxicity becomes a concern. Monitoring and managing the ppO2 during dives ensures a safer diving experience and helps divers make informed decisions about their gas mixtures and dive plans.