Oxygen and Nitrogen

[Queztacotl]

The Air is :

78% Nitrogen
21% Oxygen
1% Others

So when people ever say what do we breathe in, would it not be Nitrogen opposed to Oxygen?

[MortenS]

I believe the correct term would be that we breath in air, and then exchange oxygen and carbondioxide. 21% oxygen in, about 16% oxygen out. About 0,03% carbondioxide in, about 5% carbondioxide out. Percentage of nitrogen is unchanged.

[Jay-qu]

also dont forget that nitrogen is lighter than oxygen so the lower you go in the atmosphere the more oxygen there would be...