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Just completed my deep (40m/120ft) diver certification. A significant amount of the course was focused on nitrogen narcosis, and how to handle/detect it. Appar
by slau 3y ago
Just completed my deep (40m/120ft) diver certification. A significant amount of the course was focused on nitrogen narcosis, and how to handle/detect it.
Apparently, some divers will start feeling the narcotic effect between 20-30m. Beyond 30m, a significant amount of divers can feel the effects.
Beyond 40m is the realm of tech diving, with trimix (helium/nitrogen/oxygen) or even heliox (helium/oxygen). I know nothing about this, so I’ll let others comment.
The interesting thing about this research is that it sort of makes sense, and yet is very surprising. We’re basically continuously narked, we’re just so used to it we don’t even know.
Fun fact: the exact cause of nitrogen narcosis is not exactly understood. It is most likely the fact that at higher partial pressures nitrogen is able to enter the fatty tissues surrounding our nerves. Except for helium, no other gas exists which does not have some form narcotic effect at higher pressures.
Considering the prices of helium, this also explains why many deep divers are starting to consider rebreathers.
- killingtime74 3y agoI'm a certified Tech Diver if anyone has questions (TDI AN/DP & Heliox). Fun fact is the narcotic effect is very sudden for most people at a certain depth (30m for me) and also clears just as quickly. It's more pronounced if you are tired and/or the water is cold. Helium is very expensive like you say. Normal air fills are like $10 AUD, a tank of Trimix can be hundreds. https://www.scubadoctor.com.au/trimix-requested-mix.htm https://www.scubadoctor.com.au/trimix-requested-mix.htm. Normally you would need 3 or more 12L tanks filled with 240L of gas in each, depending on the dive. Most people who use it a lot do rebreather diving, where you can recycle a few liters over and over. The rebreather costs $10k AUD + training though and has many more parts that can fail. One is the oxygen sensor, that has limited lifespan and if it fails and you don't catch it quick enough can kill you (you switch over to bailout which is a backup gas supply).
- aaronscott 3y agoYour comment about being continuously narked reminded me how in early human history people relied on low-alcohol beer as a safe water supply. So back then it was a double-whammy. https://www.scientificamerican.com/article/the-conflicted-history-of-alcohol-in-western-civilization/ https://www.scientificamerican.com/article/the-conflicted-hi...
- alentred 3y agoAs far as I understand, historically, alcoholic beverages were primarily invented and used as a water disinfectant. Rum was used in British navy to disinfect fresh water in barrels. Wine was used to dilute it in water till the 20th century. Fun fact, in ancient Greece people who drank pure wine (not diluting it in water) were considered alcoholics and could be publicly denounced. Beer was used as a typical beverage accompanying a meal in many populations (a sandwich with a beer was the closest analogy to the "fast food"). It appears that it is only recently that we have started to consume alcohol for pleasure.
- sithadmin 3y agoI'm not sure I buy your claim that rum was ever used to 'disinfect' fresh water on British Navy ships. The 'grog' mix they used was not of sufficient ABV to disinfect the water, as it was handed out at a 4:1 ratio of water:rum. It was moreso about making the daily rum ration difficult to hoard, and much more efficient to transport than beer or wine.
- jaggederest 3y agoGrog was at least 10% alcohol, plus lime juice. Navy rum was 65% or 130 proof. That's more than enough to inhibit most waterborne diseases such as cholera (inhibited in wine at 6.25% abv, though wine has tannins and phenols).
- jerf 3y ago"We’re basically continuously narked, we’re just so used to it we don’t even know." Just because one direction on the gradient means that we respond in a way that looks like a narcotic does not mean that the other direction will respond in the opposite manner. I'm sure the nootropics folks would have discovered being super not high by now if it were as easy as breathing a mixture that doesn't have nitrogen in it.
- hn8305823 3y ago> I'm sure the nootropics folks would have discovered being super not high by now if it were as easy as breathing a mixture that doesn't have nitrogen in it. Maybe this is what Oxygen Bars are actually about but nobody knows it yet.
- genewitch 3y agoas siblings commented, pure oxygen gets you high. a couple of breaths of pure oxygen will relieve pain and induce euphoria. I am not entirely clear on the definition of "narcotic" so i may be being redundant. My issue, though, is i can't find a way to safely generate oxygen for a decent price. I know electrolysis works, but these atomic sieves look safer. They're also difficult to acquire without a prescription, at least from my searches in the US. And i know lithium can react to generate oxygen, but that's not what i consider "safe".
- tonyarkles 3y ago
- dsr_ 3y ago"Except for helium, no other gas exists which does not have some form narcotic effect at higher pressures." I assume the narcotic effect of fluorine, chlorine and bromine are basically unstudied...
- genewitch 3y agoi got a lungful of chlorine gas once and it wasn't narcotic in the slightest. I wheezed and coughed for about 20 minutes.
- gumby 3y agoIf you get more of it you definitely won't wake up.
- glitchc 3y agoYou may have confused narcotic with necrotic.
- mikercampbell 3y agoI could hear the dice rolling in my head
- nanidin 3y agoI have experienced nitrogen narcosis before. It was like getting drunk very fast, including the room spinning. I hugged myself and ascended maybe 2-4m above the rest of the group and got back to normal pretty quickly after that and was able to continue to the dive.
- naikrovek 3y agoare you using "nark" correctly? I've always thought that meant annoyed.
- slau 3y agoI am, however you’re not wrong. The main use of the word is either regarding annoyance, but can also mean snitching. “Narked” in the scuba community 100% refers to nitrogen narcosis. See the company called “Narked at 90”.
- naikrovek 3y agoI thought the snitching variant ended in "c". ok what a sheltered life I lead
- extraduder_ire 3y ago>Except for helium, no other gas exists which does not have some form narcotic effect at higher pressures. According to something mentioned in passing in a Scott Manley (amateur space youtuber) video about deep-sea diving: at high enough pressures you'll get similar effects from helium. It's thought that you can avoid this by subbing out the helium for hydrogen, but nobody so far has been insane enough to try. I assume liquid breading is much easier at that point. >The interesting thing about this research is that it sort of makes sense, and yet is very surprising. We’re basically continuously narked, we’re just so used to it we don’t even know. I'd be interested in knowing how people are mentally when they're in spacewalk/Mir conditions. (1/3rd atmosphere, pure oxygen.)
- bibanez 3y agoI only have high school level chemistry, but if Helium is a noble gas it doesn't bond and so it can't have a narcotic effect, because it doesn't affect the chemistry of the brain
- scotty79 3y agoI wonder if you could use argon instead then. And yet, argon is more narcotic than nitrogen: https://en.m.wikipedia.org/wiki/Nitrogen_narcosis https://en.m.wikipedia.org/wiki/Nitrogen_narcosis
- nradov 3y agoThe narcotic effects of inhaled gasses don't seem to have anything to do with chemical bonds. There's something else going on. Even some noble gasses like argon are highly narcotic.
- pas 3y agoIt's narcotic effect comes from lipid solubility (and because it basically crowds out other gases - likely oxygen - needed for chemical reactions). So basically, because it's an inert gas it prevents some reactions.
- scirpaceus 3y ago> It's thought that you can avoid this by subbing out the helium for hydrogen, but nobody so far has been insane enough to try. It's reportedly been done very recently using a rebreather (https://gue.com/blog/n1-the-inside-story-of-the-first-ever-h2-ccr-dive/ https://gue.com/blog/n1-the-inside-story-of-the-first-ever-h...). Prior to that, in 1992, there was the French COMEX-sponsored HYDRA 10 experiment that saw Théo Mavrostomos dry-dive in a chamber to 701 meters (71.1 bars) - the world's absolute saturation dive depth record. Though that experiment used "only" 20% H2 (https://www.newscientist.com/article/mg13618493-000-technology-dry-run-for-deepest-dive/ https://www.newscientist.com/article/mg13618493-000-technolo...).
- danw1979 3y agoI had mild nitrogen narcosis once at about 15m (regular PADI open water diver) despite doing similar depth dives before. It was a worryingly pleasant experience. Like 3 or 4 pints on a warm summer’s afternoon.
- marceldegraaf 3y agoIt's due to the narcotic effects of nitrogen that GUE (Global Underwater Explorers, a diving association rooted in tech/cave diving) uses EAN32 (32% oxygen) as their standard breathing gas. They're also more conservative in their recreational diving depths: 30m (100ft) is the recreational limit, beyond that technical certification and a helium-based breathing gas (e.g. Trimix) are required.
- nradov 3y agoI think you misunderstood the GUE standards. Nitrox isn't significant less narcotic than air. They set a 100 ft equivalent narcotic depth maximum limit somewhat arbitrarily because empirically that seems to be pretty safe. Below that depth we add progressively more helium to the mix to limit narcosis as well as gas density (work of breathing).
- todd8 3y agoWhile I am certified for Nitrox diving, I'm not sure I would actually use it very much. After over 100 open water dives and many dive classes (I was one class away from being a certified instructor back in the 1970s) I realized that I didn't want to do extreme diving. Night dives in the Caribbean are exciting enough. Wreck diving, ice diving, cave diving, commercial diving, hard hat diving all seem too dangerous. Diving in the warm, clear Caribbean was great, and 75% of that experience can be obtained with just a snorkel, mask and flippers. One of my friends was a commercial diver working on Oil platforms in the North Sea. Out of the eight divers he worked with, he is the only one that lived through it without serious injury.
- slau 3y agoNitrox is the single most issued specialisation. It’s most useful for repeat dives and on reasonably shallow dives. The most benefit you’ll get is in the 20-30m range. As I mostly dive cold waters, I use a max PO2 of 1.4, instead of the 1.6 that some people use. This means that for deep dives (30-40m), I typically end up with EAN28 instead of the more common EAN32. Nitrox is definitely not “extreme diving”, though. It’s just a way to increase your bottom time and reduce your surface interval. Just remember to keep an eye on your CNS%—there’s a limit to how much oxygen your body can safely handle.
- nradov 3y agoThere's no need to handle narcosis, just use more helium. Regardless of whether you subjectively feel it, the effect is always there and increases progressively with depth. Some divers claim that they can adapt to it and minimize the effects through repeated exposure but there's no reliable evidence that really works; I think they're just fooling themselves. Note that some of the serious narcotic effects that divers feel are often due to CO2, which is even more narcotic than nitrogen. If you exert yourself and don't ventilate effectively then hypercapnia can hit you hard. Adding more helium to the mix also helps with this by reducing the gas density and making it easier to blow off the CO2.