Why is it necessary to confirm the type of gas used before every dive?

Confirming the type of gas used before every dive is essential, particularly in the context of using nitrox or other gas mixtures, because different gas compositions can have significant effects on a diver's safety and planning. Each gas type has its own specific properties, especially regarding the partial pressures of nitrogen and oxygen, which can influence the risk of oxygen toxicity and nitrogen narcosis.

In nitrox diving, for example, the oxygen content is higher than in regular air, which can lead to oxygen toxicity if the partial pressure of oxygen exceeds safe limits. Understanding the specific gas being used allows divers to calculate their maximum operating depth and plan their dive accordingly to avoid these risks. This planning helps ensure that divers remain within safe exposure limits, thereby promoting their safety underwater.

Moreover, confirming the gas type contributes to the overall dive planning process, ensuring that the entire team is informed and prepared for the physical demands of the dive associated with the chosen gas. Therefore, this step is crucial for executing a safe and well-planned dive.