Nitrogen Narcosis While Scuba Diving

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Scuba Diving Articles - Learn To Scuba Dive
Sunday, 26 October 2008 21:27

What is nitrogen narcosis?

Nitrogen narcosis is a condition of confusion or stupor resulting from increased levels of dissolved nitrogen in the blood, occurring when breathing compressed air. Its effects usually become noticeable when diving below 30m (100ft), although it is reported some divers are affected as low as 20metres (65 feet) while some are fine at 40m (130ft).


Why is nitrogen narcosis dangerous?

In itself, nitrogen narcosis is not life threatening. The danger occurs from poor decision making while under the effects of nitrogen narcosis. A diver affected by nitrogen narcosis behaves as you might expect someone to behave if intoxicated. Narcosis will impair both the coordination and judgement of a diver, sometimes causing a false sense of security which results in foolish behaviour and a disregard for safety.

Sometimes, nitrogen narcosis can make a diver feel anxious and uncomfortable, which can lead to higher stressed and panic states, which can result in making poor decisions.


How can I avoid nitrogen narcosis?

The only sure way to prevent nitrogen narcosis is simply to avoid deep dives (greater than a depth of 30m). As we mentioned earlier, everyone is affected differently by nitrogen narcosis and it can affect the same person differently on a day to day basis. If you are going to be diving deeper than 30m, then you should be prepared and knowledgeable for the warning signs for both yourself and your buddy. If either of you suffer nitrogen narcosis, the effects will disappear when you go to shallower water.


How can I spot the signs and symptoms of nitrogen narcosis?

You can spot signs of nitrogen narcosis in your buddy by looking out for:

  • Slow reaction time to signals
  • Poor coordination and confused movement
  • Foolish behaviour and a disregard for safety
  • Anxiety or panicked movements

You can spot the symptoms of nitrogen narcosis in yourself by looking our for:

  • Feeling of wooziness / giddyness / drunk
  • Feeling of euphoria
  • Disorientation
  • Loss of balance
  • Loss of manual dexterity
  • Slowing of reaction time
  • Fixation of ideas
  • Inability to focus


What is the science of nitrogen narcosis?

Nitrogen narcosis is caused by gases in the body acting in a manner described by Dalton's Law of partial pressures: the total pressure of a gas mixture is equal to the sum of the partial pressures of gases in the mixture. As the total gas pressure increases with increasing dive depth, the partial pressure of nitrogen increases and more nitrogen becomes dissolved in the blood. This high nitrogen concentration impairs the conduction of nerve impulses and mimics the effects of alcohol or narcotics.

What should I do if I am suffering from nitrogen narcosis?


Nitrogen Narcosis

If you believe you are suffering from nitrogen narcosis then signal to your buddy, by doing the "I'm narc'd!" hand signal, which is moving your index finger in circles at the side of your head (more diving hand signals here). You and your buddy should then make a slow ascent to shallower water, while ascending at a safe rate (no more than 18m/60ft per minute) until you feel better. This procedure should be repeated if you spot signs of nitrogen narcosis in your dive buddy.

When planning a dive you should also be aware than stress factors such as cold water, physical exertion or a fast rate of compression exacerbate the onset of nitrogen narcosis.





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