Because the atmospheric pressure is lower the higher you go, at 6,500 feet [2,000 m] above sea level, a given volume of air contains some 20 percent less oxygen, and at 13,000 feet [4,000 m], air contains 40 percent less oxygen.
बहुतेक समस्या ऑक्सीजनच्या अभावामुळे निर्माण होतात.