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I just watched the movie After Earth. The air on the planet Earth, one million year after Humanity left it is still Contaminated. But there are still a large variety of flora and fauna flourishing. There are green rain forests and sunlight which should be enough for photosynthesis to occur. There should be no deficiency of Oxygen. Then why does Kitai had to take the Oxygen Extracting fluid?

marked as duplicate by user1027 Sep 30 '13 at 16:28

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