Why is it crucial to avoid hyperventilation before a dive?

Avoiding hyperventilation before a dive is crucial primarily because it can lead to decreased carbon dioxide levels in the body, which subsequently increases the risk of blackout. Hyperventilation expels an excessive amount of carbon dioxide, disrupting the body's natural balance of gases. This shift can result in hypoxia, where the brain is deprived of oxygen, eventually leading to a loss of consciousness, especially during activities demanding focus and physical exertion, such as diving.

Maintaining normal levels of carbon dioxide is vital for the body's respiratory drive and for signaling when to breathe. A drop in carbon dioxide can delay the urge to breathe, potentially causing a diver to black out underwater, leading to dangerous situations without the ability to manage one's safety. Thus, proper breathing control is essential in preventing such critical risks while diving.