A good friend of mine has the ability to consume copious amounts of alcohol and never really appears to be overly intoxicated. I know other people who start slurring their words at the mere sniff of a glass of wine. Similarly, my husband proudly boasts that he has never been “narked” (impacted by nitrogen narcosis). I, on the other hand, have experienced a plethora of narcosis related symptoms ranging from paranoia, visual hallucinations and giddiness, to, relaxation, slowed reactions and thinking. I have also witnessed countless narcosis related signs in students on deep training dives. Such “signs” have included the guy who relentlessly waved at the fish, the girl who starting conducting an orchestra at 30 metres, people rolling round in the sand in hysterics, crying and countless occasions where people failed to complete the simplest of tasks.
What is Nitrogen Narcosis?
So what is nitrogen narcosis, and, why do individuals seemingly appear to differ in their susceptibility to it?
Divers breathing compressed air are effectively breathing almost 79% nitrogen. As we descend, the partial pressure of this nitrogen increases. At 30 metres, the partial pressure of the nitrogen is effectively four times what it is at the surface, making the nitrogen more readily soluble into our tissues. Higher concentrations of nitrogen within the diver impair the conduction of nerve impulses leading to intoxication effects that are often likened to those of alcohol. This is why it is sometimes referred to as the “Gin and Tonic Effect”.
The increased nitrogen partial pressures at depth explain why the narcotic effects increase with depth. By 60 metres, tests have highlighted that diver performance is strongly affected. At such depths, every diver is impacted, even my husband who might not still know or admit it! Similarly, the effects of nitrogen narcosis are completely reversed as gas pressure decreases, so no hangover! This is why inexperienced divers are told to ascend to shallower depths if they feel any narcotic symptoms. Certainly, if at any time you do not feel comfortable with the impacts of narcosis, you should ascend to a shallower depth in any case.
Impacts of Nitrogen Narcosis
Different people do differ in their susceptibility to narcosis, and, at certain depths, whilst all divers will be impacted, some will be more clearly impacted than others. Nitrogen narcosis susceptibility is therefore no different to differing individual’s susceptibility to intoxication from any type of narcotic drug (although I’d like to think I can drink my husband under the table! ).
In certain cases, it can be argued that susceptibility to narcosis may also have a subjective component. Whilst not fully understood, external factors such as water temperature and visibility may impact on a divers susceptibility. I, for instance will almost always feel more impacted by narcosis on a temperate water dive say in Sydney Harbour in 2 metre visibility than I would at the same depth on a tropical reef. It is questionable whether my reactions or performance would be any different on these two particular dives, however, task loading (i.e. a divers ability to cope with multiple of responsibilities) and added stress in less inclement conditions may simply make a divers reactions more noticeable.
The only way to avoid nitrogen narcosis is to not dive deep. Be aware though, that you will be missing out on some fantastic dive sites that are deeper than 30 metres. With experience and dive frequency, it is however, often perceived that the effects of nitrogen narcosis reduce. In effect, divers may become acclimatised to the effects with dive frequency. This has certainly been the case for me.
If you are planning a deep dive and worried about the impacts of narcosis, get your training up to scratch. Deep training dives with an experienced instructor will ensure that you get to experience narcosis in a controlled environment. The idea being that next time you get narked, you will be able to recognise the signs and symptoms, either in yourself or in your buddy, and make allowances or take appropriate actions. These days, I know immediately when I am impacted and I make a conscious effort to keep checking my gauges, make allowances and stay safe.
So what are you waiting for? Don’t let nitrogen narcosis prevent you from experiencing some of the deeper dive sites. Dive safe, dive deeper, get narked, get the DiveBuzz!