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Global Warming
Elements and Compounds
Carbon Monoxide

Will carbon monoxide rise or fall indoors?


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April 28, 2016 6:56PM

Carbon monoxide will rise indoors. CO is slightly lighter (28amu) than O2 (32amu) which comprises about 21% of air and of equal mass to N2 (28amu) which comprises pretty much all of the remaining 79%. So its density is very slightly lower. However, the reason it is likely to rise has more to do with the fact that it is usually the result of combustion and will therefore be warmer than the surrounding air - causing it to rise.

The bottom line is this: the difference in density is so slight and the mixing of the CO with the air in a room so rapid that it would be very safe to assume that if excess amounts of carbon monoxide are present in a building they will quickly spread to all floors in a multi-story building/house. So don't just put a detector on the top floor thinking that all of the CO will end up there! If there's source of CO in your basement (or anywhere, for that matter) it could be a dangerous situation throughout the house. Install a detector on each level.