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Table 1 Signs and symptoms of nitrogen narcosis at different depths [2,29]

From: Moving in extreme environments: inert gas narcosis and underwater activities

Depth (msw) Atmospheric pressure (atm) p N2 (atm) Signs and symptoms of narcosis
0–10 1–2 0.79–1.58 Unnoticeable/minor symptoms such as subtle changes in behaviour
10–30 2–4 1.58–3.16 Mild impairment of unpractised tasks
Impaired reasoning
30–50 4–6 3.16–4.74 Delayed response to visual and auditory stimuli
Calculation errors and poor choices
Mild amnesia
Overconfidence, idea fixation and a sense of well-being
Laughter (chambers) or anxiety (cold water)
50–70 6–8 4.74–6.32 Impaired judgement and confusion
Delay in response to signals, instructions and other stimuli
Uncontrolled laughter, hysteria (in chamber)
Feelings of terror (in some)
70–90 8–10 6.32–7.90 Mental confusion
Loss of memory
Stupefaction and loss of judgement
90+ 10+ 7.90+ Hallucinations, increased intensity of vision and hearing