Nitrogen Narcosis

Nitrogen narcosis is caused by the absorption of nitrogen into the body tissues. This occurs as a result of changes in pressure at depth. Nitrogen narcosis can affect all divers, regardless of age or physical condition and is not limited to just one type of dive or one type of diving equipment.

It is the most common of diving illness, and is sometimes called raptures of the deep. Nitrogen narcosis is caused by reduced pressure. As the diver descends below 100 feet, the nitrogen in his blood absorbs in to his body tissue. Because the diver’s body will absorb nitrogen more rapidly than air at depth, he may experience symptoms of intoxication similar to alcohol by the time a depth of 150 feet has been reached.

It is a state of drug intoxication caused by breathing high concentrations of nitrogen. The symptoms are usually similar to those seen with other types of narcosis, but can vary depending on the rate at which the diver descends and ascends. The effects are generally more severe during descent than they are during ascent because there is less time between exposures to high partial pressures of nitrogen.

Nitrogen narcosis causes euphoria, over-confidence, disorientation and poor judgment; this may lead to serious errors in judgment that could result in injury or death if not treated appropriately (i.e., ascending or decompressing).

Different people experience different degrees of nitrogen narcosis depending on their individual susceptibility to it. This susceptibility typically increases with age and with excessive drinking and smoking habits. All divers are susceptible to some degree however and this should never be ignored or minimized.

The increase in susceptibility to nitrogen narcosis

The susceptibility to nitrogen narcosis increases with age and the number of cigarettes smoked per day. The more you smoke, the higher your risk of experiencing symptoms and the greater their intensity. Excessive drinking also increases your likelihood of developing symptoms of nitrogen narcosis. There are a few other factors that can affect someone’s susceptibility to this condition:

  • The amount of time spent diving;
  • The depth achieved during dives;
  • Your body mass index (BMI); and
  • Your genetic make-up

How does it happen?

Imagine you’re at the bottom of a swimming pool. If you stay there long enough, your body will get used to breathing water and eventually stop noticing that it’s there. This is similar to what happens when divers breathe air under pressure at depth. The nitrogen in the air becomes concentrated in their bodies and can have harmful effects on their mental state.

When you dive to deep depths or spend an extended amount of time underwater while breathing compressed air, nitrogen narcosis begins to affect your brain function. In fact, this phenomenon has been known since the early 1900s when divers realized they felt drunk after diving below 100 feet (30 meters).

How do you know if you are experiencing nitrogen narcosis?

If you’re worried that you might be experiencing nitrogen narcosis, there are a few key signs to look out for.

  • You’ll start to feel euphoric, which is essentially how people describe being drunk (and why alcohol is sometimes referred to as “liquid courage”).
  • You may also start hallucinating. If this happens, stay calm and try to explain what’s happening in a rational manner to whoever around you—even if they aren’t listening.
  • You’ll begin to lose consciousness and fall into an unconscious state similar to sleep or drunkenness where breathing becomes more difficult. At this point, it’s time for action!

How it affects divers?

You may have heard the term “nitrogen narcosis” bandied about in diving circles, but do you really know what it means? Nitrogen narcosis is a condition that occurs when divers breathe compressed air at depths below 130 feet. Compressed air contains nitrogen, and at high concentrations, this substance can cause a variety of symptoms—from euphoria to muscle paralysis.

As with anything else related to diving and/or water, there’s always a risk that something bad could happen while you’re out on the sea—and nitrogen narcosis is one of those risks. In fact, if you’ve ever dived more than 100 feet below sea level (which is far deeper than most recreational divers go), then chances are good that your body experienced some sort of effect from breathing compressed air. But don’t worry: The effects will pass once the diver surfaces again!

How to avoid nitrogen narcosis?

  • Avoid diving in deep water
  • Always dive with a buddy
  • Take a course and learn how to dive
  • Have a good knowledge of the dive site
  • Be aware of the effects of alcohol and drugs before diving
  • Have a good knowledge of your physical condition


Diving is a wonderful sport that can provide you with a lifetime of joy and adventure. But diving is also serious business, and it’s important to understand the risks associated with it before taking your first plunge. Nitrogen narcosis is one of these risks, but it can be avoided by following a few simple precautions. Always remember that safety in numbers is key when scuba diving or freediving—you want someone on deck who knows what they’re doing at all times!

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