breath

The air we inhale is roughly 78% nitrogen, 21% oxygen, 0.96% argon and 0.04% carbon dioxide, helium, water, and other gases.
The gases we exhale are roughly 78% nitrogen, 15% to 18% oxygen, 4% to 5% carbon dioxide and 0.96% argon.
Additionally, vapors and trace gases are present: 5% water vapor, several parts per million (ppm) of hydrogen and carbon monoxide, 1 ppm of ammonia and less than 1 ppm of acetone, methanol, ethanol, and other volatile organic compounds.