Scuba Diving International (SDI) Computer Nitrox Practice Exam

What should divers avoid in order to reduce the risk of oxygen toxicity?

1. Long dive sessions

2. High physical exertion underwater

3. Breathing pure oxygen at depth

4. Using a Nitrox mix

The correct answer is: Breathing pure oxygen at depth

To reduce the risk of oxygen toxicity, it is important for divers to avoid breathing pure oxygen at depth. Oxygen toxicity occurs when there is an excessive partial pressure of oxygen in a diver's breathing gas. At greater depths, the pressure increases, which in turn raises the partial pressure of oxygen in the mixture being breathed. Pure oxygen at depth can lead to a toxic buildup, affecting the central nervous system and possibly leading to serious complications like convulsions underwater. In recreational diving, the use of pure oxygen is generally restricted to surface use or in specific situations like decompression chambers, rather than being integrated into mixtures for use at depth. This practice helps to maintain safe levels of oxygen exposure for divers, thus lowering the risk of oxygen toxicity. Other considerations, such as managing dive duration, controlling physical exertion, and using appropriate gas mixtures like Nitrox, also contribute to safe diving practices but do not directly relate to the high risk posed by breathing pure oxygen at depth. Maintaining awareness of gas mixtures and pressures is crucial for safe diving experiences.