How are nitrogen narcosis and decompression sickness connected to nitrogen gas under pressure?

Both nitrogen narcosis and decompression sickness are physiological consequences of breathing nitrogen under increased pressure, such as during underwater diving. Because nitrogen is an inert gas, it accumulates in body tissues and fluids when breathed at high pressures, with higher concentrations absorbed at greater depths.12

• Nitrogen Narcosis: This is a reversible change in consciousness caused by the direct effect of excess nitrogen dissolved in the nervous system. Because nitrogen is highly soluble in lipids, it accumulates in lipid-rich tissues like the brain, potentially impairing cell function and causing symptoms ranging from euphoria and light-headedness to irrationality and unconsciousness. These effects typically dissipate upon ascent.1

• Decompression Sickness: This occurs when a diver ascends too rapidly, causing the excess nitrogen that was dissolved in the tissues to come out of solution and form gas bubbles. These bubbles can obstruct blood flow or damage tissues, leading to severe pain, paralysis, or other systemic symptoms.32

To mitigate these risks, divers must ascend slowly to allow nitrogen to be exhaled through the lungs, or use gas mixtures like helium and oxygen, which are less soluble in body tissues.312