How can nitrogen dissolved in body fluids cause decompression sickness?

Decompression sickness occurs when nitrogen, which is inert and accumulates in body tissues under high pressure, forms gas bubbles during a rapid transition to lower pressure.12

At atmospheric pressure, the body contains small amounts of dissolved nitrogen. However, when a person—such as an underwater diver—is exposed to increased pressure, they absorb significantly more nitrogen as it dissolves into their tissues and fluids. Because nitrogen is highly soluble in lipids, it accumulates particularly in fatty tissues, including the nervous system.12

If the ascent to a lower-pressure environment is too rapid, the body cannot expel the excess nitrogen through the respiratory system fast enough. Consequently, the nitrogen comes out of solution and forms bubbles within the tissues. These bubbles can cause severe damage by obstructing blood flow or physically disrupting tissues, leading to symptoms such as joint pain, paralysis, and respiratory distress. Treatment typically requires recompression to shrink the bubbles and allow for gradual elimination of the gas.1