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I was recently backpacking in Olympic National Park. I didn't have a tarp with me (was being cheap. Bought one shortly after the trip) but had a $5 umbrella. It rained a bit during one the mornings and I was cooking under my umbrella (the main reason I brought it) to protect the stove from getting wet. One thing that occurred to me as I was cooking is the umbrella was probably collecting some of the gases from the stove. Once in a while I kinda tilted the umbrella a bit to "let the gas out" from underneath.

My question: Do I risk suffocation while cooking under an umbrella?

I've thought about it more since my trip and am inclined to think no. I feel as though there is enough airflow under the umbrella and so as long as I am not sticking my head up to the very tippy top of the umbrella to breath I am fine. But curious to hear the thoughts of others.

  • Not really, it is quite common to cook in a tent and even more common to heat large venues with gas heaters. Just don't leave it to heat your tent slowly while you lie in your sleeping bag. – Vladimir F Sep 23 at 8:49
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The answer to this is a resounding: No.

The main problem with suffocation and cookers is in enclosed spaces where there is no airflow. Suffocation when using a cooker can happen when either the O2 concentration drops below the minimum needed, or when the CO2 (carbon dioxide) or CO (carbon monoxide) concentration rises to a toxic point. In the case of cookers both scenarios can happen if the air-flow is low enough. CO and CO2 are both undetectable without specialist equipment at levels which are toxic to humans.

Under normal conditions and assuming your cooker is working properly, the cooker will be producing mostly carbon dioxide. This alone is not toxic enough to be deadly as our bodies have very efficient mechanisms for removing CO2 from our systems. If the cooker is not working properly or is without an adequate oxygen supply (as you might find in an enclosed space), then you will be generating carbon monoxide. This gas bind irreversibly to our hemoglobin and accumulates in the system, and is much more commonly responsible for deaths from enclosed spaces than CO2.

In the case of camping all it takes when you have a tent or similar space is to leave the door open. This will provide enough air exchange to maintain both proper burning of the cooker (and less CO produced).

With your umbrella, even at the peak of the umbrella, there is unlikely to be a toxic environment as the cooker is creating a constant up-rising of hot gasses, including those drawn in along with the gasses that have been burnt. These gasses mix enough that you would be unlikely to suffer any serious side effects from breathing this mix.

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    Carbon dioxide can be detected by humans before it is getting dangerous: you'll feel unwell and tired. – Jasper Sep 21 at 15:05
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    @Darren - no, CO has a molecular mass of 28, the same as nitrogen molecules which are the major constituent of air. CO2 is heavier. In any event, stratification or air by molecular mass will not occur in an outdoor environment. – Jon Custer Sep 21 at 15:52
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    @JonCuster you’re right, turns out CO being heavier than air is a well-known “myth”. – Darren Sep 21 at 15:57
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    @Jasper Sure, but those symptoms are pretty nonspecific and people rarely realise that they're being caused by carbon dioxide concentration. Detecting symptoms isn't the same thing as detecting the cause of those symptoms. – David Richerby Sep 21 at 17:35
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    @Jasper, the big symptom to look for with carbon-dioxide poisoning is rapid breathing or a feeling like you can't get enough air. Our breathing isn't triggered by a shortage of oxygen, but by a buildup of carbon dioxide. – Mark Sep 21 at 19:42
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CO2 is not a problem in cooking combustion quantities AND is significantly denser (so "heavier") than air.

As fyrepenguin said

"At STP, air is 1.29 g/L, while CO is 1.25 g/L.".

Molecular weights per gram mol are

  • CO 28 grams

  • O2 32 grams

  • N2 28 grams

  • O2:N2 at 1:4 ratio 29.2 g.

I'd expect CO to JUST rise - but with open sides and even a modest thermal stream it should be absolutely fine (for most values of absolute :-) ).

If you didn't subsequently get a headache you got no significant CO input.
A headache is an indicator that you received a survivable dose that was higher than you should have allowed yourself to receive.

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    As already discussed in other comments: Molecular mass of air components is totally irrelevant. The component mix, they do not separate. Otherwise You'd have pure O2 on the earths surface/bottom of the atmosphere. – imsodin Sep 23 at 12:52
  • @imsodin For atmospheric 'air' I agree. I was showing where the final figure came from. I also did not use the fractional gram mol masses that gives a slightly different figure. || Where individual gas densities matter is in the period post generation where longer term mixing has not occurred. Time to mix deep-ends on diffusion, air currents, thermal stream etc. In a well ventillated environment it is highly unlikely that pooling of either lower or higher density than air gases will occur to a significant extent. However, people die in "gas pockets" when ventillation is not adequate. – Russell McMahon Sep 23 at 15:05
  • "Longer-term mixing" is effectively instantaneous. the carbon dioxide is quite hot (so "lighter") and will billow around. If your face isn't being burned, the carbon dioxide it's inhaling has mixed with the surrounding air. – Sneftel Sep 23 at 15:35
  • @Snweftel: Interest only. In NZ, stand by a running car with bare feet or sandals and you may feel the warm air on your feet. Sometimes quite hot but never painful. Do that in Phoenix at 45C and leap away in pain as ambient + delta = wow!. Ask me how I know :-) – Russell McMahon Sep 24 at 2:04
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I assume by "gas" you mean the exhaust from your stove? Carbon monoxide? If you're using isobutane (typical US backpacking stove fuel) CO is not normally a significant emission. Even if it were, you'd have to be cooking in a pit or an enclosed space for it to accumulate as CO is heavier than air. (It has been pointed out to me the CO is in fact lighter than air, so text relating to that has been struck out, thank you for enlightening me, SE.)

You are not in danger of suffocation from this, now fire on the other hand... just don't get your plastic umbrella too close to the flame!

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    Carbon monoxide is actually nearly the exact same density as regular air; it's actually slightly lighter. At STP, air is 1.29 g/L, while CO is 1.25 g/L. You may be thinking of CO2, which is 1.98 g/L at STP, which is a fair amount heavier. – fyrepenguin Sep 21 at 14:51
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    If the flame is burning properly the exhaust from your stove is predominantly CO2 and water. But when you try to use your stove to heat your house and it consumes too much oxygen to 'complete combustion', it starts forming only CO and you die. – Mazura Sep 23 at 2:53
  • CO is lighter than most air. Hot CO will rise above cold air anyway. Even hot CO2 will float above cooler air. Anything which is not oxygen filling the space you are breathing in can cause suffocation. Please consider revising your answer to ommit the inaccuracies. Your point about needing to be in an eclosed space to have a high risk of suffocation and about the fire being the greater hazard are good. – TafT Sep 23 at 16:06

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