Biology Question #339

Rick Anderson, a 15 year old male from the Internet asks on February 15, 1998,

Is the air we exhale pure carbon dioxide? If not, then what is it?

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The answer

Barry Shell answered on February 15, 1998

It's far from pure carbon dioxide. Not at all. First of all, like all of the air on the earth, it's about 78% nitrogen. There's also still a lot of oxygen in exhaled air. It goes down to about 17% from the normal 21% in regular air. The amount of carbon dioxide in exhaled air is about 3%. The rest is made up of water vapour and trace gases always present in normal air.

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