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Why one still gets nitrogen narcosis if per Breathing gas, "most breathing gases [...] are a mixture of oxygen and one or more inert gases", ie similar or identical to air? The narcosis article says high pressure is involved, but I still don't understand why when the breathing mix is basically air and not a pure nitrogen. 212.180.235.46 ( talk) 21:44, 29 February 2020 (UTC)
The Breathing gas#Oxygen article discusses the risk of oxygen toxicity. The article specifically mentions
andThe fraction of the oxygen determines the greatest depth at which the mixture can safely be used to avoid oxygen toxicity. This depth is called the maximum operating depth.[1][3][6][9]
andThe maximum safe PO2 in a breathing gas depends on exposure time, the level of exercise and the security of the breathing equipment being used. It is typically between 100 kPa (1 bar) and 160 kPa (1.6 bar); for dives of less than three hours it is commonly considered to be 140 kPa (1.4 bar), although the U.S. Navy has been known to authorize dives with a PO2 of as much as 180 kPa (1.8 bar).[1][2][3][6][9] At high PO2 or longer exposures, the diver risks oxygen toxicity which may result in a seizure.[1][2] Each breathing gas has a maximum operating depth that is determined by its oxygen content.[1][2][3][6][9]
Our Gas blending for scuba diving also discusses oxygen toxicity although mostly just says similar stuff.where the oxygen content exceeds atmospheric levels, generally to a level where there is some measurable physiological effect over long term use, and sometimes requiring special procedures for handling due to increased fire hazard. The associated risks are oxygen toxicity at depth and fire, particularly in the breathing apparatus.[citation needed]
We even have a Maximum operating depth article which mentions
In case it's unclear from these, Enriched Air Nitrox and Trimix (breathing gas)#Hyperoxic trimix are used in certain circumstances. But obviously just increasing the oxygen concentration does not work for many cases.This limit is based on risk of central nervous system oxygen toxicity, and is somewhat arbitrary, and varies depending on the diver training agency or Code of Practice, the level of underwater exertion planned and the planned duration of the dive, but is normally in the range of 1.2 to 1.6 bar.[1]
BTW, you might also be interested in Trimix (breathing gas)#Advantages of keeping some nitrogen in the mix, High-pressure nervous syndrome, Trimix (breathing gas)#Disadvantages of helium in the mix, Compression arthralgia and Decompression sickness. The effect of using helium on the risk of decompression sickness, is different from what I had understood until now, and I wonder if User:Trovatore may also share some confusion in the area. Likewise, I wasn't aware of the other reasons besides cost why you may not want to just use heliox.
BTW, despite that one citation needed tag, our articles look in decent shape albeit I haven't checked the quality of the references and do not know about the subject. I.E. I'm just assuming from the referencing and writing it's not utter nonsense.
One example, I noticed our article mentions
Yet I came across [1] which makes me think there may be some dispute over what is necessary and why. But this is also very recent, and I have no idea how well accepted it is.Helium dissolves into tissues (this is called on-gassing) more rapidly than nitrogen as the ambient pressure is increased. A consequence of the higher loading in some tissues is that many decompression algorithms require deeper decompression stops than a similar decompression dive using air, and helium is more likely to come out of solution and cause decompression sickness following a fast ascent.[9]
Nil Einne ( talk) 15:50, 2 March 2020 (UTC)
Science desk | ||
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< February 28 | << Jan | February | Mar >> | March 1 > |
Welcome to the Wikipedia Science Reference Desk Archives |
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The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
Why one still gets nitrogen narcosis if per Breathing gas, "most breathing gases [...] are a mixture of oxygen and one or more inert gases", ie similar or identical to air? The narcosis article says high pressure is involved, but I still don't understand why when the breathing mix is basically air and not a pure nitrogen. 212.180.235.46 ( talk) 21:44, 29 February 2020 (UTC)
The Breathing gas#Oxygen article discusses the risk of oxygen toxicity. The article specifically mentions
andThe fraction of the oxygen determines the greatest depth at which the mixture can safely be used to avoid oxygen toxicity. This depth is called the maximum operating depth.[1][3][6][9]
andThe maximum safe PO2 in a breathing gas depends on exposure time, the level of exercise and the security of the breathing equipment being used. It is typically between 100 kPa (1 bar) and 160 kPa (1.6 bar); for dives of less than three hours it is commonly considered to be 140 kPa (1.4 bar), although the U.S. Navy has been known to authorize dives with a PO2 of as much as 180 kPa (1.8 bar).[1][2][3][6][9] At high PO2 or longer exposures, the diver risks oxygen toxicity which may result in a seizure.[1][2] Each breathing gas has a maximum operating depth that is determined by its oxygen content.[1][2][3][6][9]
Our Gas blending for scuba diving also discusses oxygen toxicity although mostly just says similar stuff.where the oxygen content exceeds atmospheric levels, generally to a level where there is some measurable physiological effect over long term use, and sometimes requiring special procedures for handling due to increased fire hazard. The associated risks are oxygen toxicity at depth and fire, particularly in the breathing apparatus.[citation needed]
We even have a Maximum operating depth article which mentions
In case it's unclear from these, Enriched Air Nitrox and Trimix (breathing gas)#Hyperoxic trimix are used in certain circumstances. But obviously just increasing the oxygen concentration does not work for many cases.This limit is based on risk of central nervous system oxygen toxicity, and is somewhat arbitrary, and varies depending on the diver training agency or Code of Practice, the level of underwater exertion planned and the planned duration of the dive, but is normally in the range of 1.2 to 1.6 bar.[1]
BTW, you might also be interested in Trimix (breathing gas)#Advantages of keeping some nitrogen in the mix, High-pressure nervous syndrome, Trimix (breathing gas)#Disadvantages of helium in the mix, Compression arthralgia and Decompression sickness. The effect of using helium on the risk of decompression sickness, is different from what I had understood until now, and I wonder if User:Trovatore may also share some confusion in the area. Likewise, I wasn't aware of the other reasons besides cost why you may not want to just use heliox.
BTW, despite that one citation needed tag, our articles look in decent shape albeit I haven't checked the quality of the references and do not know about the subject. I.E. I'm just assuming from the referencing and writing it's not utter nonsense.
One example, I noticed our article mentions
Yet I came across [1] which makes me think there may be some dispute over what is necessary and why. But this is also very recent, and I have no idea how well accepted it is.Helium dissolves into tissues (this is called on-gassing) more rapidly than nitrogen as the ambient pressure is increased. A consequence of the higher loading in some tissues is that many decompression algorithms require deeper decompression stops than a similar decompression dive using air, and helium is more likely to come out of solution and cause decompression sickness following a fast ascent.[9]
Nil Einne ( talk) 15:50, 2 March 2020 (UTC)