Night steemit friends ..... this time I will open the secret of breathing for divers .....
Question....
Why do divers, fire officers, and mountaineers use oxygen cylinders?
 
The lungs are unable to separate oxygen mixed in water. Whereas humans need oxygen when diving. That is why divers breathe oxygen from the tubes carried on their backs.
 
Smoke-filled air cannot be for breathing. That is firefighters need oxygen oxygen in carrying out work to get clean air.

The higher the place on the surface of the earth, the less oxygen is in the air. As a result, mountaineers have difficulty breathing and need additional oxygen.
So, from me, @wondo may be of benefit to all of us, and thank you for visiting our friend on my blog.
By, @wondo