how is mouth to mouth (CPR) beneficial if you’re blowing carbon dioxide into their lungs?

Question

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In: Biology

Answer 1

Common misunderstanding!

Air you breathe in: 78% nitrogen, 21% oxygen, ~1% argon.

Air you breathe out: 78% nitrogen, 17% oxygen, 4% carbon dioxide, 1% argon.

So what you exhale is still 17% oxygen, only down 4% from normal air (!), and it’s only 4% carbon dioxide.

**TLDR:** **Blowing in 17% oxygen with 4% CO2 is better than them getting no oxygen at all.**