Inhaled air is by volume 78.08% nitrogen, 20.95% oxygen and small amounts include argon, carbon dioxide, neonhelium, and hydrogen.

 - The gas exhaled is 4% to 5% by volume of carbon dioxide, about a 100 fold increase over the inhaled amount.

 - The volume of oxygen is reduced by a small amount, 4% to 5%, compared to the oxygen inhaled.

 - The typical exhaled composition is: