Nitrogen narcosis is a condition that occurs in divers while breathing compressed air. When divers go below depths of approximately one hundred feet, increase in the partial pressure of nitrogen produces an altered mental state similar to alcohol intoxication. A similar phenomenon also affects crews while space walking.
During the Omega training mission on Titan, in the mid-22nd century, the EV pack that Charles Tucker wore froze up on him, causing him to experience nitrogen narcosis. Delirious and fearful he was going to die, he started to try to take off his helmet. His commanding officer, Jonathan Archer, however, ordered him to keep it on and Tucker obeyed that order because he trusted Archer. Archer would recall the incident, when he and Tucker were placed in a similar situation in 2151, when they were both affected by a hallucinatory pollen on an uncharted class M planet. (ENT: "Strange New World")