Drowning on Purpose: Can humans breathe liquid?
With any luck, in your life you will get somewhere in the neighbourhood of 672,768,000 breaths. Most of those will be pretty run-of-the-mill in terms of their ingredients: 78% nitrogen, 21% oxygen, and 1% argon. Occasionally you might mix it up if you end up in the hospital, go to space or hit up one of those weird oxygen bar things. You might even breathe in something nasty like cigarette smoke either on purpose (why?)…