injuries and poisoning
Altitude Illness
Acclimatization
The body eventually adjusts (acclimatizes) to higher altitudes by increasing respiration, by producing more red blood cells to carry oxygen to the tissues, and by making other adjustments. Most people can adjust to altitudes of up to 10,000 feet (3,000 meters) in a few days. Adjusting to much higher altitudes takes many days or weeks, but some people can eventually carry out nearly normal activities at altitudes above 17,500 feet (about 5,300 meters). However, no one can fully acclimatize to long-term residence above that altitude. Symptoms of acute mountain sickness (AMS) may be mistaken for a hangover, physical exhaustion, a migraine, or a viral illness. 