How does a higher percentage of oxygen in Nitrox affect a diver's physiology?

A higher percentage of oxygen in Nitrox can indeed lead to oxygen toxicity, which is a serious concern for divers using enriched air mixtures. Oxygen toxicity occurs when divers are exposed to elevated partial pressures of oxygen, which can happen at greater depths or when using gas mixtures that contain higher concentrations of oxygen than the standard atmospheric level of 21%.

As a diver descends, the pressure increases, and consequently, the partial pressure of oxygen in their breathing gas also increases. This elevated partial pressure can lead to harmful physiological effects, including central nervous system toxicity, which can result in symptoms such as visual disturbances, muscle twitching, seizures, and in severe cases, loss of consciousness.

It's crucial for divers to understand not only how to use Nitrox but also the implications of varying oxygen levels in their breathing gas and to monitor their exposure to avoid complications associated with oxygen toxicity. Proper diving practices, including monitoring depth and time, adhering to recommended gas mixtures, and understanding Maximum Operating Depths for specific Nitrox mixes, can mitigate the risk of oxygen toxicity.