http://en.wikipedia.org/wiki/Atmosphere_of_Earth http://en.wikipedia.org/wiki/Atmosphere_of_Earth That makes it 95.6% oxygen. Probably good enough for most pu

http://en.wikipedia.org/wiki/Atmosphere_of_Earth http://en.wikipedia.org/wiki/Atmosphere_of_Earth That makes it 95.6% oxygen. Probably good enough for most purposes. And the bulk (96%) of the non-oxygen is argon, which is inert.