What is the primary concern with hyperventilation before a dive?

Hyperventilation before a dive primarily leads to carbon dioxide depletion. When a diver hyperventilates, they are breathing at an abnormally high rate, which reduces the concentration of carbon dioxide (CO2) in their blood. This can result in respiratory alkalosis, where the blood becomes too alkaline due to decreased CO2 levels.

The concern with low levels of carbon dioxide is significant because CO2 plays a crucial role in stimulating the body's drive to breathe. Without adequate CO2, a diver may not feel the need to take breaths, leading to a risk of hypoxia, or insufficient oxygen in the body. This decreased urge to breathe can result in a dangerous situation underwater, such as passing out due to low oxygen levels.

Carbon dioxide also helps maintain proper blood pH balance and ensures that oxygen is delivered effectively to tissues. Therefore, hyperventilation poses a risk by significantly altering these physiological processes, making carbon dioxide depletion the primary concern before a dive.