What do humans breathe in?
Like other things in life, breathing isn't that simple. What we breathe in is far from pure oxygen, but roughly by volume 78 per cent nitrogen, 21 per cent oxygen, 0.965 per cent argon and 0.04 per cent carbon dioxide (plus some helium, water and other gases).
Join Alexa Answers
Help make Alexa smarter and share your knowledge with the worldLEARN MORE