What is the purpose of utilizing a surface interval when using Nitrox?

Utilizing a surface interval is essential when diving with Nitrox as it allows the body to eliminate inert gases, particularly nitrogen, that accumulate during a dive. When a diver is underwater, especially at greater depths, nitrogen from the breathing gas is absorbed into the body’s tissues and bloodstream. The purpose of a surface interval is to provide the necessary time for off-gassing, which is the process where nitrogen is released from the tissues back into the bloodstream and then expelled from the body through exhalation.

This process is crucial for divers to help reduce the risk of decompression sickness (DCS), also known as "the bends." Adequate surface intervals ensure that nitrogen levels decrease to safer levels before a subsequent dive, allowing divers to dive again with a lower risk of accumulating too much nitrogen, which could lead to dangerous situations like DCS. The choice to allow the body to eliminate these gases is particularly important when using Nitrox because its higher oxygen content affects the way that gases are utilized and released by the body during and after a dive.