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Q: suffocation, lung capacity, human oxygen useage ( Answered ,   1 Comment )
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 Subject: suffocation, lung capacity, human oxygen useage Category: Science Asked by: jrudland-ga List Price: \$2.00 Posted: 19 Sep 2003 04:50 PDT Expires: 19 Oct 2003 04:50 PDT Question ID: 258239
 ```how long does it take to suffocate in an air tight room? i.e if I had a 10 x 10 x 2 Meter room, how long would it take an average male to suffocate?```
 Subject: Re: suffocation, lung capacity, human oxygen useage Answered By: knowledge_seeker-ga on 19 Sep 2003 06:32 PDT Rated:
 ```Hi jrudland-ga, The issue of suffocating in an enclosed space is not one of running out of oxygen; it's one of being poisoned by carbon dioxide -- CO2. CO2 becomes toxic at a concentration of 1%. (Normal atmospheric concentration is 0.036 percent (360 ppmv).) A concentration of 10% can cause respiratory paralysis and death within a few minutes. How fast the CO2 level builds depends on how fast you produce it. This would be related to how fast you are breathing. At rest you would exhale much less than if you were exercising. Given that a moderately active or stressed person produces about 1.7 cubic feet of CO2 per hour and assuming a concentration of 3% CO2 is the highest safe limit, here is an equation you can use to calculate how long a given number of people can stay in a given space before toxic levels of CO2 build up --- T = Number of hours of air in a sealed room (Volume of air inside the room in cubic feet) x (3% or 0.03) T = --------------------------------------------------------- (Number of people) x (one person's hourly production of CO2) Scroll down this page for explanation of that equation FOR YOUR SAFETY - Sealed Room Atmosphere http://yahweh.com/News/07_2002/NL7-02.html So….using the Google calculator – Your room of 10x10x2 meters would be – 200 (cubic meters) = 7 062.93334 cubic feet. Let's call that 7000 cubic feet. T = (7000 x .03) / (1 x 1.7) = 210/1.7 = 123.5 hours. ------------ From a Science Fiction author --- "As it turns out, a 10 X 10 X 10 foot space, or 1,000 cubic feet, will be filled with a lethal concentration of CO2 by one resting human sized individual in just 24 hours. (The CO2 level reaches about 1% in that time). Moderate activity will cut this time to 12 hours, and strenuous activity to 6 hours." Suffocation, CO2 poisoning http://www.frontiernet.net/~jamesstarlight/Suffocation.html Let's check that with our equation ---- (1000 x .01) / 1.7 = 17 hours. Close. ---------------- This website addresses oxygen depletion, but ignores CO2 concentrations, which makes their answer to the question, "How long can we survive in an enclosed space?" entirely wrong. I include it because I suppose these equations would be useful if you were using up air in the room, but exhaling out through a tube or if you employed air scrubbers to remove the CO2. Question: How long can 10 healthy adult people survive in a sealed room of dimensions 3m x 4m x 2.5m before they run out of oxygen (i.e. the oxygen concentration drops to 12%)? An adult of average weight consumes about 3.33 10-6 m3 s-1 of oxygen while at rest. The typical volume of an adult is 0.1 m3. Answer: The equation for rate of change of oxygen concentration in an enclosure without oxygen replacement (neglecting the buildup of carbon dioxide) is: (total oxygen consumption rate) = (volume of oxygen consumed) / (total time lapsed) or : nC = {Vr - nVp}{Li - Lf}/t [see explanations here] How long can we survive in a sealed enclosure? http://www-das.uwyo.edu/~geerts/cwx/notes/chap01/ox_exer.html --------------------- A hypothetical question to a Biosphere scientist -- "[an adult] would need about 350 litres of oxygen per day (the amount of oxygen in 1.7 cubic metres of air)." Biosphere http://www.newscientist.com/lastword/article.jsp?id=lw564 ----------------- Safety Information for Cavers (Spelunkers) – this is a good table that shows the stages of Co2 poisoning at different concentrations [scroll down] CARBON DIOXIDE, CAVES AND YOU Table 2. Generally accepted physiological effects of CO2 at various concentrations by volume http://wasg.iinet.net.au/Co2paper.html -------------- So, that should answer your question, and then some. I hope you find the additional information useful as well. Thanks for an interesting question! -K~```
 jrudland-ga rated this answer: ```Thanks for a quick and complete answer. I has answered the question I should have asked perfectly - top marks in my book!!!```

 Subject: Re: suffocation, lung capacity, human oxygen useage From: stevenpace-ga on 12 Oct 2003 04:54 PDT
 ```The old home remedy for CO2 was lime. More efficient CO2 scrubbers have followed, but depending on the situation, natural CO2 removal might occur. It is important to remember, for example, that oxygen does not disolved very well in water, but C02 does, especially cold water. And as long as the PH of the water stays high, the water will keep absorbing the CO2 forever. That is why lime was used. The earths oceans are currently absorbing a bit of extra C02, for example.```