While making some search for this question I found this article on LV-223 article on Xenopedia (emphasis mine)

The atmosphere's main components are similar to Earth's; 71% nitrogen, and 23% oxygen. However, there is a high level of carbon dioxide, which constitutes 3% of the atmosphere. This is more than enough to be fatal to humans in a very short exposure. It also contains small amounts of argon, as detected by the spaceship Prometheus.

So I checked Carbon Dioxide Toxicity on Wikipedia. Here an excerpt (emphasis mine) :

Adaptation to increased levels of CO2 occurs in humans. Continuous inhalation of CO2 can be tolerated at three percent inspired concentrations for at least one month and four percent inspired concentrations for over a week.

However the LV-223 article on the alien anthology wikia sightly differ (emphasis mine) :

The atmosphere is composed of 71% of nitrogen, 3% carbon monoxide, 23% oxygen and traces of argon gas. It also contains small amounts of argon, as detected by the spaceship Prometheus. The air on LV-223 is mostly identical to Earth's atmosphere, but contains poisonous levels of carbon dioxide (CO2) making it impossible for humans to breathe outside. (Earth levels average about .0389% for comparison)

So I checked Carbon monoxide poisoning on Wikipedia

12,800 ppm (1.28%) Unconsciousness after 2–3 breaths. Death in less than three minutes.

I did not find any official source to say which one is right. While the plot suppose monoxide, I just want to know if they goof in the movie.

  • 3
    I think one problem is the accuracy of wikia and other fan wikis - they're typically not well-researched, and very little review is given on content there.
    – HorusKol
    Commented Oct 18, 2012 at 22:48

3 Answers 3


I've downloaded a few subtitles and looked through them. They all have the quote:

00:23:45,995 : CO2 is over 3 percent.

00:23:48,122 : Two minutes without a suit, you're dead.

This means there was probably a goof in the movie. Although, technically the CO2 could be around 7%, it just doesn't make sense why she would say 3.

  • 6
    @NominSim because levels of 3% carbon dioxide won't kill you in 2 minutes. It's more of a scientific misstatement I guess.
    – John
    Commented Oct 18, 2012 at 17:22
  • 8
    If CO2 was that toxic, mouth to mouth resuscitation would be lethal!
    – Mr Lister
    Commented Oct 18, 2012 at 18:33
  • 5
    Despite what was listed, for the level of lethality required, carbon MONOXIDE was what they meant, not what they SAID. So many people are working on scripts and movie productions these days, such tiny errors slip past all the time. No scientist should be without a job with all of the scientific screw ups in most modern movies. Commented Oct 18, 2012 at 23:02
  • 2
    Plainly they meant carbon MONoxide (CO) but neither the script writer nor the actors knew the difference.
    – user12945
    Commented Mar 6, 2013 at 0:55
  • 1
    Yes to both of the above. The action of CO (MONoxide) is to bind to the oxygen sites in hemoglobin, forming carboxyhemoglobin. This is a tighter bind than O2 makes, so the oxygen carrying capacity of the blood is lessened because the O2 can't dislodge it. Enough CO and you basically smother to death. It's treated with 100% O2, usually at pressure (Hyperbaric chamber).
    – JohnP
    Commented Oct 29, 2013 at 22:04

The Centers for Disease Control and Prevention states that the IDLH (Immediately Dangerous to Life and Health) levels for Carbon Dioxide is 40,000 ppm (4%). Also, it has been reported that submarine personnel exposed continuously at 30,000 ppm (3%) were only slightly affected, provided the oxygen content of the air was maintained at normal concentrations according to Schaefer KE [1951]. Studies of carbon dioxide toxicity. New London, CT: Navy Department, Bureau of Medicine and Surgery, Medical Research Laboratory, U.S. Naval Submarine Base, Vol. 10, Report No. 181, pp. 156-189.

50,000 ppm (5%) results in signs of intoxication and 70,000 - 100,000 (7-10%) ppm produce unconsciousness according to the CDC.

Yes. The movie absolutely goofed. Further, the Carbon Dioxide Information Analysis Center states that a human exhales approximately 3.7% CO2 by volume. If 3% were deadly, then rescue breathing would be impossible.


Here is the dialog from the movie (Source):

Janek: What is the atmosphere?

Ravel: Atmosphere is 71 percent nitrogen, 21 percent oxygen, traces of argon gas.

Holloway: Just like home.

Ford: Only if you're breathing through an exhaust pipe. CO2 is over 3 percent. Two minutes without a suit, you're dead.

Notice the last line:

  • Carbon Monoxide (CO) comes out of exhaust pipes and is toxic.

  • Carbon Dioxide (CO2) comes out of lungs and is NOT toxic. As long as there's still enough oxygen in the air to breath, humans can easily tolerate 3% CO2 for hours or days at a time.

In short, the movie goofed.

  • Were these the subs you turned on for DVD/blu-ray on directors cut? Commented Oct 29, 2013 at 23:11
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    @NOT: I edited my answer to include a link to the IMDB source where I got the dialog. I did confirm by downloading an English "subtitles" file from subscene.com. It said the same thing. --- Stan: Wiki states CO2 is an "asphyxiant" gas; and that it's categorized as non toxic. Wiki also says: "Continuous inhalation of CO2 can be tolerated at three percent inspired concentrations for at least one month and four percent inspired concentrations for over a week."
    – Lakey
    Commented Oct 31, 2013 at 3:45
  • 1
    What I had an issue with was the 'easily' .. 'for hours/days'. Would you consider a situation where you're breathing at twice your normal rate for a month an easily tolerable situation ? The CO2 table you reference does come from a scholarly article while the links I provided (which also appear to come from reasonable sources) state that CO2 is a toxic gas, go figure :)
    – Stan
    Commented Nov 1, 2013 at 13:34
  • 1
    @Stan, I think we are meaning the same thing, but the phrase "easily tolerable" might have different subjective implications to each of us. I just meant that if one can "tolerate" a month (without dying), then one can "easily tolerate" hours/days (without dying). But I completely agree with you that it would not be easy or comfortable at all. It would of course be intolerable to most people in that sense.
    – Lakey
    Commented Nov 3, 2013 at 20:47
  • 1
    As this is the future, who knows what comes out of an exhaust pipe?
    – Schwern
    Commented Aug 13, 2014 at 19:08

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