What is high altitude sickness? High altitude sickness is the cause of a symptom of the lesser amount of oxygen at High Altitude.

Remember this, the law of gravity pulls every compound to the surface of the earth, including air. That is why the density of air (thickness of air ) is at the maximum at sea level. Which the majority of humans are accustomed to. So if you go to higher places like in Tibetan plateau.

The main course of high altitude is our body demand equal amounts of oxygen as it is accustomed to. Due to the lack of it in the atmosphere, body response is the leading cause of high altitude sickness.