What gases make up the Earth`s atmosphere?
Our atmosphere is made up of 78% Nitrogen, 21% Oxygen and about 1% of everything else, we actually breathe out about 15% oxygen, our lungs aren’t all that efficient that is why if you want to hold your breath you can last longer if you let the air out very slowly because it stirs the air in the ‘dead air spaces’ (everywhere but the alveoli) and gets it into the alvoli so the oxygen in it can be used.
