“Prolonging shallow stops — either safety or obligatory — is cheap insurance. Stay long, breathe easy.”
Carbon Dioxide Level
Elevated levels of carbon dioxide can increase the risk of DCS and lower the threshold for oxygen toxicity. Carbon dioxide is a potent vasodilator, meaning it causes the blood vessels to widen, increasing blood flow and the delivery of gases to tissues. Factors that can raise divers' carbon dioxide levels include the increased dead space of breathing equipment (gas volume that must be moved but does not take part in gas exchange), the additional work of breathing dense gas underwater, and exercise. Using a well-designed and well-maintained breathing system, minimizing physical effort and remaining relaxed while underwater can minimize carbon dioxide increase.