SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/aero-atmosphere-nitrogen

Which gas makes up most of the air we breathe?

Nitrogen, about 78 percent of the air.

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  1. Nitrogen ✔
  2. Oxygen
  3. Carbon dioxide

Why: Many people guess oxygen, but nitrogen is about 78 percent of the air. Oxygen is about 21 percent, and the last 1 percent is argon, carbon dioxide and other gases.

Huh, didn't know that: Nitrogen and oxygen together make up about 99 percent of the atmosphere.

The dad joke
Why is nitrogen so popular? It is in the majority of every room.
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References

Answer: Nitrogen. Many people guess oxygen, but nitrogen is about 78 percent of the air. Oxygen is about 21 percent, and the last 1 percent is argon, carbon dioxide and other gases.

  1. FAA Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 12 Weather Theory www.faa.gov/regulations_policies/handbooks_manuals/aviation/faa-h-8083-25c.pdf
    nitrogen accounts for 78 percent of the gases that comprise the atmosphere, while oxygen makes up 21 percent
    Checked 2026-10-10.

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