Nitrogen Narcosis During A Scuba Dive

Nitrogen Narcosis can occur while scuba diving at depth and produces a feeling similar to being intoxicated. It does not usually become noticeable until you reach a depth of at least 30 meters. 

Diver having his ait gauge checked during a deep dive.

The air we breathe contains roughly 79% Nitrogen and 21% Oxygen. Nitrogen is an inert gas which means it is not used by the human body During a scuba dive you are breathing Nitrogen and Oxygen under pressure which can have a narcotic effect on the diver.

As you dive deeper the effects are enhanced, E.G. a diver at 30 meters depth is breathing air that is four times denser than at the surface and the effect upon the body will also be four times as great. Nitrogen Narcosis is also known as ‘The Rapture of the Deep’ or the Martini effect.

Scuba diver with his regulator out of his mouth.

What causes Nitrogen Narcosis?

Nitrogen is absorbed by the fatty body tissues much faster than by other tissues. Consequently, when a high concentration of nitrogen is breathed, the nervous system starts to become saturated with the inert gas, and normal bodily functions can become impaired. Mild cases begin as an intoxicating feeling of lightheadedness, euphoria, numbness, and carefreeness. 

Some divers experience narcosis in shallower water, while others can dive to 60 m with no effect. If you keep descending during a Deep Dive the symptoms increase in severity. When the diver ascends, the symptoms tend to wear off with no effect on the body. 

Other signs and symptoms may occur as the diver approaches the limits of recreational diving. For example, divers breathing regular air at 40 meters have been known to feel a sense of euphoria but this can quickly be replaced by anxiety. After realizing that these feelings of elation are not normal, the diver has to remain calm and ascend to a shallow depth and back into his comfort zone.

Divers can learn to cope with some of the effects of narcosis. The effects vary widely from dive to dive, and between individuals.

Narcosis may be completely reversed in a few minutes by ascending to a shallower depth, with no after-effects. Nitrogen narcosis while diving should not become a problem as long as the diver is aware of its symptoms, and is able to ascend to manage it.

The recreational Diving limit is 40m and anything beyond is considered a technical dive. Nitrogen and oxygen toxicity can become a serious issue during a Technical dive and because of this, specialist training is required.