What is a potential hazard when using a Nitrox blend with a high percentage of oxygen?

Using a Nitrox blend with a high percentage of oxygen poses a potential hazard of oxygen toxicity. This concern arises because higher partial pressures of oxygen can lead to toxic effects on the central nervous system and the pulmonary system during dives. Oxygen toxicity can cause symptoms ranging from visual disturbances and twitching to severe complications like convulsions, particularly at depths where the pressure increases the partial pressure of oxygen in the breathing gas.

The risk of oxygen toxicity varies based on the depth of the dive, the specific Nitrox blend in use, and the duration of exposure. It is critical for divers using Nitrox to understand their blend's maximum operating depth (MOD) to help minimize the risks of oxygen toxicity. This knowledge empowers divers to make informed decisions about their dive plans, ensuring they stay safely within limits.

While nitrogen narcosis is often a concern with deeper dives due to the effects of nitrogen at higher pressures, it isn't directly related to the use of a high oxygen percentage. The other options—decreased visibility underwater and enhanced buoyancy effects—do not accurately reflect the specific hazards associated with high-oxygen Nitrox blends.