It was observed again and again in the movie Avatar that humans could not breathe the air present in Pandora. So it can be assumed Oxygen was not present in Pandora. But again the human fires which erupted in the Hometree bombing, wouldn't be sustained if there was no Oxygen at all. So what were the components present in the air of Pandora? On the other hand if there was Oxygen, why could not the humans breathe there? So was the atmosphere in Pandora Oxygen filled or Oxygen free?

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    Why did you assume there was no oxygen? Why not assume the simplest: that there is noxious components to the air?
    – wallyk
    Jul 23, 2013 at 18:19
  • So how are the human pilots (especially the female ) seen several times without any mask??
    – user19138
    Feb 22, 2015 at 6:44
  • There shouldn't be high levels of CO2 on an undeveloped planet that is lush and green with giant trees.
    – user20704
    Apr 22, 2015 at 18:10
  • 2
    @bob In Cambrian level of CO2 was much higher than now
    – Mithoron
    Apr 23, 2015 at 22:58
  • 2
    And they're alien plants, who knows what gases they take in and/or convert.
    – sirjonsnow
    Apr 4, 2017 at 11:59

4 Answers 4


Quoting from Pandora wiki:

Pandora's Atmosphere components:

Pandora's atmosphere is a mixture of nitrogen, oxygen, carbon dioxide (>18%), xenon (>5.5%), methane, and hydrogen sulfide (>1%) and is about 20% denser than the atmosphere on Earth primarily due to the high percentage of Xenon; a heavy, colorless, odorless, and generally unreactive noble gas.

Why can't human breathe in Pandora:

The high concentration of carbon dioxide in the Pandoran atmosphere makes it extremely poisonous to humans, rendering them unconscious in about 20 seconds and causing death in about 4 minutes. The hydrogen sulfide present is also quite poisonous; concentrations over 1000 ppm (0.1 %) can cause immediate collapse with subsequent loss of breathing, even after inhalation of a single breath.

So Oxygen is present there and that's why combustion is possible.

  • 3
    I don't really think you can get much more of a textbook answer than that!
    – Liath
    Jul 23, 2013 at 15:40
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    @Liath, Absolutely.. As it is an imaginary planet, every detail fact is derived from the works related to it.
    – Mistu4u
    Jul 27, 2013 at 6:24
  • Exposing pretty much anything that level of hydrogen sulfide would make it stink to high-heaven to a human. Apr 3, 2017 at 23:33
  • I guess they have to deal with a lot of global warming for that excessive CO2
    – azerafati
    May 26, 2018 at 4:11
  • It may be worth pointing out that the Wiki is quoting from what appears to be an un-official book: james-camerons-avatar.fandom.com/wiki/… So the answer may not be 100% official.
    – Longshanks
    Feb 3, 2021 at 20:45

I concur... In high Carbon Dioxide situations, a human will hyperventilate as the brain forces the body to expel the excess and rebalance it's oxygen. If the imbalance persists, loss of consciousness and death may follow. In the film, this was portrayed very accurately when the hero was exposed to the Pandoran atmosphere. There is Oxygen present, (as was mentioned- combustion is possible) and thus death was not immediate, and recovery was rapid once Carbon dioxide was reduced.


Both answers are correct. There is oxygen so combustion is possible, but because there are so many other elements in the air on top of oxygen, it would make it impossible for human to breathe that air and survive. The human body would hyperventilate as it tries to reduce the amount of Carbon Dioxide and get more oxygen in but this put the body under stress because it is also trying to keep you conscious. The human body is designed to try to keep you alive with out stressing the body out to much, keeping you conscious and trying to expel Carbon and increase the oxygen consumption would just over stress the body, therefore, it would try to relieve some of the stress by stopping certain unnecessary or currently less vital functions so it would make the human lose consciousness for a period of time until it has the oxygen levels back under control. Having this stress on the body would make you lose consciousness within 20 seconds but you would continue to live for the next few minutes because your body is still trying to make a feeble attempt to regain control, which of course will not happen with insubstantial amounts of oxygen in the air, so, after a few minutes your body slowly starts to shut down until you die.

In conclusion, there is oxygen in the Pandora atmosphere so combustion and limited breathing is possible but there isn't enough oxygen for the human body to survive for any longer than a few minutes, in which you would be unconscious. But the Na'Vi people have bodies that are designed to breathe the air with all of those different chemicals in it. Mixing the Human DNA with the Na'Vi DNA would mean that the body would be primarily Na'Vi design but the mind would be by human design. It would be a happy medium between the two species so the Avatar is able to survive just as perfectly as the Na'Vi.


I was hoping to get a real science based answer. I didn’t see one. So I’ll add my views: there are 4 things I can think of that would provide for such big people and critters on earth. 1) Oxygen content 2) Gravity 3)Atmospheric apressure 4)Food availability. There are probably more, but I’m looking at the Dinasaour era. Oxygen would need to be higher, gravity was the same, I believe atmospheric pressure was same, food would have been greater or equal. So oxygen was rather important, in fact, they believe the Brontosaurus had multiple pumps/minor hearts up and down its neck to enable blood flow to the brain as the arterial pressure without assist pumps would have been impossible with flesh.

Given those those parameters, and an interesting statement above, I suspect the Nabi were more plant based and breathed CO2, makes sense since all creatures including plant life were connected.

I would like to hear the answer from the writer.

  • 2
    What do you mean, there's no science-based answer? The accepted answer already states that Pandora's atmosphere contains toxic levels of CO2 and hydrogen sulfide. How much more science-based do you want?
    – F1Krazy
    Nov 4, 2018 at 9:19

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