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Chapter 18 — 1
Chapter 18
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NITROGEN
NARCOSIS
(COMPRESSED AIR
INTOXICATION,
RAPTURE OF THE DEEP,
INERT GAS NARCOSIS, NARCS)
Intoxication in divers is not confined exclusively to beach barbeques and hotel bars. When
breathed under pressure, nitrogen (which makes up 78% of air) has an intoxicating effect
which, like alcohol, is variable and may lead to pleasure or disaster.
This phenomenon was regarded as an annoyance to the helmet diver who could be pulled to
the surface by his attendant if he behaved irrationally, but the consequences to the scuba
diver, who's safety is dependent on a buddy exposed to the same effect, can be more serious.
It will be present in all divers breathing air at a depth in excess of 30 metres, although some
will notice it earlier. Others may not be aware of the effect, as judgment and perception are
affected. The severity of symptoms and the exact depth of their onset varies between
individuals. Because of narcosis, diving on air beyond 30 metres (100 feet) is not prudent,
and 40 metres is considered unsafe for most recreational divers. A 50 metres depth is
considered the maximum safe depth for experienced professional divers breathing air.