Movie vs reality: in reality, medical devices don't have easy kill-the-patient modes. E.g. O2 level never below 21%.pic.twitter.com/xLlxfnv88n
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In this case, it's because the Earth's atmosphere is 21% oxygen - the machine would have to remove O2 to go lower! :)
Its all supplied from the wall. You /could/ make one that used the N2 line as base, and could feed less than 21% O2.
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