Apart from the depth and the time divers spend under water, other factors influence the absorption and elimination of Nitrogen that can contribute to a developing decompression illness. Although staying within the limits of the recreational dive planner tables minimizes this risk, the tables become less reliable and accurate in the presence of predisposing factors.
Predisposing factors include: a high level of fat tissue, older age, dehydration, injury and illness, alcohol or narcotic consumption, fatigue, elevated levels of Carbon Dioxide, diving in cold water, strenuous exercise while diving and after diving, flying after diving, and smoking.
Divers that are very overweight become susceptible to decompression illness because fat, unlike muscle, is a slow tissue that holds a high amount of dissolved nitrogen. Having a high level of body fat thus increases the amount of nitrogen that the body retains after diving. When conducting multiple dives, this can be especially risky. In addition, as a diver ages, the circulatory and respiratory systems no longer work as efficiently as they did in younger years. If the age factor is present and coupled with circulatory problems caused by being overweight, the diver becomes more prone to acquiring decompression illness.
Consumption of alcohol, caffeine, narcotics, smoking and fatigue are also factors that can lead to Decompression Illness. Alcohol and caffeine lead to dehydration, which reduces the amount of blood available for gas exchange, slowing down Nitrogen elimination from the body.
Injuries and illness can also be contributing factors to Decompression Illness. Scar tissue resulting from past injuries can inhibit or slow down the dissolving of Nitrogen and may trap silent bubbles that could expand during ascent.
Illnesses can weaken the body’s natural defenses and cause fatigue also making the diver more susceptible to Decompression illness.