Humans need oxygen and air pressure to live. Breathing is made possible by oxygen in the atmosphere reaching the air sacs in our lungs. As elevation rises atmospheric pressure goes down as the atmosphere becomes thinner. Therefore, the amount of oxygen entering the blood stream declines and it becomes harder to breathe.
If the amount of oxygen in the blood is less than the body needs, several symptoms emerge: extreme fatigue, headaches, dizziness, nausea, and loss of judgement. When a certain height is reached, it finally becomes impossible for a human being to breathe at all. This is why we need oxygen bottles and special clothing to survive at such elevations.
Someone at 5,000-7,500 metres above sea-level may faint and go into a coma because of breathing difficulties. That explains the presence of oxygen equipment in airplanes. There are also special systems that regulate air pressure when planes fly at 9,000-10,000 metres above sea-level.
Changes that take place with increasing height are indicated in the Qur’aan, well before air travel:
When Allah desires to guide someone, He expands his breast to Islam. When He desires to misguide someone, He makes his breast narrow and constricted as if he were climbing up into the sky. (Qur'an, 6:125)
The Qur’aan is true in every fine detail
