PADI Divemaster Certification Practice Exam

How can a diver avoid CNS toxicity while using enriched air?

1. By ascending quickly

2. By exceeding an oxygen partial pressure of 1.6 bar

3. By being trained and staying below 1.4 bar

4. By using standard air mixtures only

The correct answer is: By being trained and staying below 1.4 bar

To avoid Central Nervous System (CNS) oxygen toxicity while using enriched air, remaining below an oxygen partial pressure of 1.4 bar is essential. CNS toxicity becomes a risk when the partial pressure of oxygen (PO2) exceeds certain levels, with a significant increase in risk occurring when it approaches or surpasses 1.6 bar. By adhering to the limit of 1.4 bar, divers effectively reduce the likelihood of experiencing symptoms of CNS toxicity, such as seizures or other neurological issues that can arise from elevated oxygen levels. This guideline is a fundamental aspect of safe diving practices when using enriched air, underscoring the importance of both training and awareness of gas partial pressures in dive planning. Proper training equips divers with the knowledge needed to recognize and manage potential risks associated with using enriched air. Therefore, maintaining oxygen partial pressures below 1.4 bar ensures a safer diving experience.