In Avatar The Way of Water (2022), Spider says to Avatars:

Spider: You know what really sucks though? Is you can breathe Earth air for hours, and I can only breathe your air for, like, 10 seconds.

Why can Avatars breathe Earth's air, but humans cannot breathe Avatar air?

  • 1
    sounds like there are limitations on avatars also. on earth, whales go without breathing for an hour. maybe a similar thing with avatars, they store what they need for a long time -- they may breathe out of reflex but earth air does not supply some critical gas. humans may be poisoned by some gas in avatar air.
    – releseabe
    Oct 22, 2023 at 5:52
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    I always thought it was difference between breathing, drinking and eating. For humans, it is as if they are not breathing, 4 minutes holding your breath tops. For Avatars, it is as if they are not drinking water, three days tops. Humans can survive weeks without food and then they die.
    – jo1storm
    Oct 22, 2023 at 6:07
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    There's the Avatar fandom site, but as far as I know that's not considered cannon as it's not (again, as far as I know) officially endorsed. That gives a breakdown of Pandora's atmosphere, but the source isn't cited for those data. Oct 22, 2023 at 6:37
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    Is this really a special feature of Na'vi avatars, or is it common to all Na'vi in general? Oct 22, 2023 at 6:40
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    There's some nonsense on the wiki page about the Na'vi having a special organ to deal with the methane in the atmosphere. I can't find any canon basis for it and it appears to be a case of citogenesis
    – Valorum
    Oct 22, 2023 at 9:34

1 Answer 1


Humans wear exopacks because of the presence of an unpleasant chemical (hydrogen-sulfide) in the Pandoran atmosphere as well as the high levels of CO2.

Pandora is not Earth, and its paradise is deceiving. The nitrogen-oxygen atmosphere is 20 percent denser than our own. It contains so much carbon dioxide (more than 18 percent) that humans who breathe it will rapidly lose consciousness and die. Another gas, hydrogen-sulfide, is spewed out by pervasive vulcanism, and is toxic In concentrations far less than 1 percent. It must be removed by the exopack's mask along with the CO2 The heavy gas xenon comprises about 5.5 percent of Pandora's atmosphere, and is responsible for much of the increased air density. Although Pandora's air is denser than Earth's, the sea level pressure is about 10 percent less, in part because the moon's gravity is only 80 percent of Earth's.

James Cameron's Avatar: An Activist Survival Guide

Since the exopack is making use of the Pandoran atmosphere (and merely removing certain poisonous chemicals) the Na'vi can apparently breathe their own modified air without the need for filters, although the low concentrations of CO2 seems to make this unpalatable after a time, like humans breathing a pure oxygen atmosphere.

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