Almost all diving fatalities are caused by errors on the part of the diver. These errors can be attributed to a number of factors. The main contributing factors are improper training, diving beyond the qualification level and dive conditions.
Pre-existing health conditions are also factors that affect the safety of divers. These include heart disease, respiratory abnormalities, and high blood pressure. Other conditions that can be risky include ear problems, sea sickness, and vomiting.
In addition to pre-existing health conditions, other factors that affect the safety of divers include improper training, diver fatigue, and improper buoyancy. These factors are often overlooked during the investigation of a diving accident.
The most common contributing factors for fatal diving accidents are pulmonary barotrauma, air embolism, nitrogen narcosis, and cardiovascular failure. These conditions occur when gas enters arterial blood via ruptured pulmonary vessels. The bubbles in the arterial blood can travel to the heart and brain.
Asthma is another contributing factor in many diving fatalities. In one study, it was estimated that 0.5% to 1% of recreational divers have asthma. It can be caused by ear problems, alcohol, or salt water aspiration.
Incorrect equipment can also contribute to a diving accident. Problems with cylinders, weight belts, or wetsuits are common. These problems can cause unconsciousness or overexpansion. They are generally avoidable.
When diving, a diver should follow the recommended service intervals for his or her equipment. In many cases, equipment failures are avoidable. Usually, equipment failures are obvious before the dive.