Nitrox and Reducing Nitrogen Narcosis

[dougchartier]

Although I haven't yet been certified for nitrox (but hope to soon), I'm curious to learn more about it. In addition to its commonly-noted benefits of increasing NDLs (albeit with a lower maximum operating depth) and reducing surface intervals, I was wondering how effective nitrox is at reducing the effects of nitrogen narcosis. I presume that, given its lower nitrogen content, this would be an additional benefit, although the degreee of benefit must vary depending upon the type of nitrox used and would not be as great as with heliox and trimix.

I was hoping you could tell me (1) how effective is nitrox at reducing nitrogen narcosis and (2) do divers ever choose nitrox exclusively because of its advantages with respect to nitrogen narcosis (i.e., more bottom time and shorter surface intervals are not important to their dive plans).

Thanks in advance!

 

[ppo2_diver]

Oxygen is actually more narcotic than Nitrogen (according to lipid solubility tests). So I treat Nitrox just as narcotic as air. I use Nitrox for longer bottom times and the shorter SIs. Narcosis does play into the deeper divers, but I don't dive Nitrox mixtures deeper than 100 feet. So the narcosis isn't THE highest concern.

 

[HowardE]

Nitrox does not reduce the effects of nitrogen narcosis in any measurable amount. (look up the term END - Equivalent Narcosis Depth)

I dive nitrox because of the added benefit of longer NDL's at recreational depths.

 

[Tomeck]

I was in the hospital, after the operation, I breathed 100% oxygen during 12 hours, I had narcosis. I don't believe nitrox reduced narcosis.

 

[Sas]

(1) how effective is nitrox at reducing nitrogen narcosis

Some people swear black and blue that nitrox reduces narcosis. I am not convinced. I've only used nitrox a few times, but once I was at around 28m (diving with EAN32) and was narced out of my gourd. That is the shallowest by far that I have experienced very noticable narcosis. Whilst there are many factors that contribute to narcosis, and the nitrox may have had nothing to do with the severity of the narcosis I experienced, I know I can still get very narced with nitrox so I do not expect to have reduced narcosis with it.

(2) do divers ever choose nitrox exclusively because of its advantages with respect to nitrogen narcosis (i.e., more bottom time and shorter surface intervals are not important to their dive plans).

I know a few people who use it for this reason, but I would not say they use it exclusively for this reason.

 

[dougchartier]

Oxygen is actually more narcotic than Nitrogen (according to lipid solubility tests). So I treat Nitrox just as narcotic as air. I use Nitrox for longer bottom times and the shorter SIs. Narcosis does play into the deeper divers, but I don't dive Nitrox mixtures deeper than 100 feet. So the narcosis isn't THE highest concern.

I wasn't aware of O2's narcotic effects (only its toxicity). I'm curous, do you know at what depths and percentages of oxygen in the mix do you feel noticeable narcotic effects from oxygen? And are the effect similar to nitrogen narcosis?

 

[battles2a5]

The science behind it is somewhat controversial. Some agencies treat O2 as narcotic, some don't. In the end, the only person that should make the decision is you. Personally, I feel that air and nitrox are similar in terms of narcosis, so I don't consider one to have an advantage over the other in that regard. Onset of narcosis is largely dependent on the diving environment, your perception of narcosis, and you physiology. Some people "get narced" at shallower depths in cold dark water, some get narced everywhere. I think a lot of it has to do w/ how you perceive it and where you are in terms of situational awareness. In cold dark water, you are focused more on your immediate surroundings and you world gets "smaller" if that makes sense. You are too busy looking at the pretty fishes and singing "under the sea" in the tropics so the effects may not be as noticeable. You are also less likely to build up CO2 in that environment (wetsuit, AL80, easy to move around) which I think is a much larger factor in narcosis than N2/O2.

So in the end, it depends on the individual. Slowly expand your limits and then plan accordingly once you determine what depths you are comfortable diving in any given environment.

 

[dougchartier]

Nitrox does not reduce the effects of nitrogen narcosis in any measurable amount. (look up the term END - Equivalent Narcosis Depth)

Thanks, that's quite helpful. I found this table online (http://www.bimson.com/diving/end.pdf) and sort of see what you mean. According to the table (I'm assuming it was correctly calculated), a dive on EAN32 to 34 meters has an END of 28 meters. Does that 6-meter difference not result in much of a difference in risk of nitrogen narcosis? I have little experience in this area, but I would think that diving at 90 feet (on air) poses a non-trivially lower risk of getting narced than diving at 110 feet.

 

[Wayward Son]

I get buzzed easier on nitrox than I do on air.

 

[jridg]

The narcosis effect varies from diver to diver. I notice a narcosis around 110 feet on air - of course with EAN32 - you are limited to 110 ft.

I normally limit my depth to 100ft with 32 and have never noticed any narcosis effect.

For me, the major benefit is reduced nitrogen uptake overall. If I am assisting with a couple of classes and dive five times in a day on air, I tend to get a headache at the end of the day. If I do the same on EAN32, I don't have that problem.

Your mileage may vary