Into thin air: Medical problems at new heights
It used to be a problem for the very few, the hardy adventurers who trek or climb at breathtaking heights. But high places continue to beckon, and as travel becomes easier and less expensive, more and more men are responding with their ascent. If you maintain a low profile, you don't have to worry about altitude sickness, but if your travel plans are uplifting, you should know how to handle new heights.
Although a low oxygen level is the most obvious and important cause of altitude sickness, several factors actually combine to trigger problems: