What gas is primarily responsible for causing DCS?

Decompression sickness (DCS), commonly known as "the bends," is primarily caused by nitrogen. When a diver or aviator is subjected to changes in pressure, such as ascending rapidly from deep waters or experiencing a quick descent to lower altitudes, the body’s nitrogen levels can fluctuate. Under high pressure, nitrogen gas from the air is absorbed into the body's tissues and fluids at increased amounts. However, when the pressure decreases too quickly, the dissolved nitrogen can form bubbles. These bubbles can lead to various symptoms and physiological challenges as they obstruct blood vessels and damage tissues.

In the context of aviation and rapid decompression, nitrogen is the gas that poses the highest risk because it is inert and not metabolized by the body. While oxygen and carbon dioxide are essential for respiration and are actively managed by the body, nitrogen does not serve a metabolic function and can become problematic under rapid decompression scenarios. Helium, while used in specialized diving situations, is less implicated in DCS than nitrogen, further solidifying nitrogen's role as the primary gas responsible for this condition.