Argon is the third most common gas found in the air we breathe. The air we breathe has approximately 78% nitrogen and 21 % oxygen. The third more abundant gas in the air we breathe is Argon. It is available in a very small quantity in the air that we breathe. The percentage of the gas argon is about 0.9% in the air that we breathe. There are several other gases also present in the air that we breathe, but they are found mostly in negligible amounts.