Decompression illness (DCI) is primarily caused by:

Decompression illness (DCI) is primarily caused by the formation of microscopic bubbles of nitrogen in body tissue. This occurs when a diver ascends too quickly after spending time at depths where they are exposed to increased pressure. Under high pressure, more nitrogen is dissolved in the bloodstream and tissues. When ascent occurs rapidly, the reduction in pressure causes nitrogen to come out of solution and form bubbles, which can lead to a range of physiological effects.

These bubbles can disrupt blood flow and damage tissues, leading to symptoms such as joint pain, dizziness, and in severe cases, can affect the central nervous system and other vital organs. This mechanism is central to understanding why safe ascent rates and proper diving practices are critical in preventing DCI. Other responses, while they may be related, do not accurately define the primary cause of DCI the way the formation of nitrogen bubbles does.