Scuba Diving International (SDI) Computer Nitrox Practice Exam

What is the primary purpose of a Nitrox mixture in diving?

1. To enable deeper dives

2. To extend dive time and decrease nitrogen absorption

3. To reduce the weight of scuba equipment

4. To promote buoyancy control

The correct answer is: To extend dive time and decrease nitrogen absorption

The primary purpose of a Nitrox mixture in diving is to extend dive time and decrease nitrogen absorption. Nitrox, which is a mixture of oxygen and nitrogen, typically contains a higher percentage of oxygen than regular air. This higher oxygen content means that the diver has less nitrogen in their breathing gas, which, in turn, reduces the amount of nitrogen the body absorbs during the dive. By decreasing nitrogen absorption, Nitrox allows divers to extend their bottom time at certain depths before they reach their no-decompression limits. This is particularly advantageous for repetitive dives or for divers looking to maximize their time underwater. Additionally, lower nitrogen levels can also reduce the risk of decompression sickness, as less nitrogen is build-up in the body tissues. The other options, while relevant to diving, do not accurately describe the primary purpose of using a Nitrox mixture. For example, while some divers may use Nitrox for certain depths, it is not intended for enabling significantly deeper dives, as the effects of increased oxygen toxicity become a concern at deeper depths. Moreover, Nitrox does not directly influence buoyancy control or reduce the weight of the scuba equipment, although it might offer some convenience in terms of dive time and safety.