Which risks are heightened as ppO2 levels exceed 1.6 ata?

When partial pressure of oxygen (ppO2) levels exceed 1.6 ata (atmospheres absolute), the risk of Central Nervous System (CNS) oxygen toxicity significantly increases. This condition arises due to the production of reactive oxygen species, which can lead to cellular damage in the central nervous system. Symptoms may include visual disturbances, twitching, and seizures, which are critical factors to monitor during dives with elevated oxygen levels.

The regulatory guideline of 1.6 ata as a maximum ppO2 is established to maintain safety and mitigate these toxicity risks. At levels higher than this, the likelihood of adverse neurological effects escalates, making awareness and adherence to ppO2 limits crucial during dives, especially when using Enriched Air Nitrox.

While there can be other factors like physical strain or fatigue that might not be directly associated with high ppO2 levels, they do not represent the immediate or critical risks posed by oxygen toxicity. Decompression illness, on the other hand, is more related to nitrogen absorption and off-gassing rather than oxygen. Understanding these dynamics is essential for safe diving practices with enriched air.