How does nitrogen narcosis occur in divers?

Nitrogen narcosis occurs primarily because of the increased partial pressure of nitrogen experienced by divers at greater depths. As a diver descends, the ambient pressure increases due to the weight of the water above. This increased pressure causes more nitrogen, which is a major component of the air we breathe, to dissolve in the body’s tissues and blood. When the partial pressure of nitrogen rises, it begins to have a narcotic effect on the central nervous system, similar to that of alcohol, leading to impaired judgment, decreased motor function, and altered sensations.

The specific mechanism of nitrogen narcosis relates to how gases behave under pressure. At greater depths, the concentration of nitrogen in the body increases, and its effects can alter cognitive functions and coordination. Divers typically start to feel the effects of narcosis around depths of 30 meters (approximately 100 feet), though sensitivity varies among individuals.

The other options address related concepts in diving physics but do not capture the direct cause of nitrogen narcosis. For example, while increased levels of oxygen can present other risks (like oxygen toxicity), they are not the cause of narcosis itself. The decrease in ambient pressure would occur during ascents and does not contribute to narcosis, but instead,