What causes CNS oxygen toxicity?

CNS oxygen toxicity occurs primarily due to elevated partial pressures of oxygen, particularly when the partial pressure of oxygen (PPO2) exceeds certain thresholds. When the PPO2 is greater than 1.3 atmospheres absolute (ata) in a wet environment or over 2.4 ata in a dry environment, it leads to harmful biochemical effects in the central nervous system. These high pressures can induce oxidative stress and the formation of free radicals, which can damage neuronal cells and lead to symptoms such as seizures, visual changes, and other neurological disturbances.

The effects of CNS oxygen toxicity become more pronounced with increased PPO2, making the correct interpretation of pressure limits essential for safe diving practices. Understanding these limits helps divers manage their oxygen exposure and avoid conditions that could compromise their health during and after dives.