Thin Air Breathing
Why is it hard to breathe in thin air?
What health dangers do mountain climbers face at high altitudes?
Among the obvious dangers of losing ones footing, the oxygen available
in the air is considerable less at higher altitudes. If I recall
correctly, 21% of the atmosphere at standard temperature and pressure at
sea level is composed of oxygen. This is less at higher altitudes.
One can lose consciousness and even die in an oxygen deficient
environment with changes from oxygen content to lower than 19.5%. This
can unfortunate effect can occur within minutes.
The air is not really thin at high altitudes. The problem is that air
pressure is lower. As altitude increases, air pressure decreases. In order
for your lungs to fill with air, the air pressure in your lungs has to be
less than the pressure of the air outside your lungs. Air moves from areas
of higher pressure to lower pressure. As your diaphragm (the muscle that
separates your chest cavity from your abdominal cavity) moves downward, the
size of your chest cavity increases. This decreases the pressure in your
chest and air flows in. When the diaphragm is up, it puts pressure on the
chest cavity and the pressure in the lungs is greater than outside the lungs.
Air flows out. This is an example of Boyle's Law. The movement of the
diaphragm is controlled by the brainstem. Anyway-the reason that it is
harder for some people to breathe at higher altitudes is that the air
pressure differences aren't as great between the inside of the lungs and
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Update: June 2012