Scuba Diving International (SDI) Computer Nitrox Practice Exam

What is a safe practice regarding PO2 to avoid oxygen toxicity during Nitrox dives?

1. Keep PO2 below 1.3

2. Limit dives to less than 18 meters

3. Maintain a deep dive profile

4. Use only pure oxygen

The correct answer is: Keep PO2 below 1.3

Keeping the partial pressure of oxygen (PO2) below 1.3 is a vital practice to prevent oxygen toxicity during Nitrox dives. Oxygen toxicity can occur when divers are exposed to high levels of oxygen, which can lead to various adverse effects, including convulsions and other neurological issues. By staying below a PO2 of 1.3, divers reduce the risk of such toxic reactions, especially during deeper dives where the pressure increases the partial pressure of gases. This practice is particularly important as divers plan their Nitrox mixtures; the mixture's oxygen content, combined with depth and the corresponding increase in pressure, determines the actual partial pressure experienced. Understanding this principle helps divers make informed decisions about their dive profiles, ensuring both safety and enjoyment while maximizing the benefits of using enriched air Nitrox.