Question

why is it difficult to breathe in higher altitudes? Why do climbers have to carry an oxygen cylinder on high mountains​

Answer 1

Explanation:

In order for your lungs to breathe air in without duress, the pressure has to be higher outside your body. But at high altitudes, the outside air pressure is lower than it is inside your lungs, making it more difficult to pull in the thinner air and for your veins to pump oxygen throughout the body.