[QUOTE=OutandBack;500034]Geez he's not climbing Everest.
A person does not have to be climbing Everest to get altitude sickness. The hunter we rescued was flown out by helicopter. The flight nurse who was onboard told us that many Colorado residents who live in Denver get altitude sickness when they go to Aspen or Vail to ski on a weekend.
Here is part of the Wikipedia article on it:
Altitude sickness—also known as acute mountain sickness (AMS), altitude illness, hypobaropathy, or soroche—is a pathological effect of high altitude on humans, caused by acute exposure to low partial pressure of oxygen at high altitude. It commonly occurs above 2,400 metres (8,000 feet).   It presents as a collection of nonspecific symptoms, acquired at high altitude or in low air pressure, resembling a case of "flu, carbon monoxide poisoning, or a hangover". It is hard to determine who will be affected by altitude sickness, as there are no specific factors that compare with this susceptibility to altitude sickness. However, most people can climb up to 2,400 meters (8,000 ft) normally.
Acute mountain sickness can progress to high altitude pulmonary edema (HAPE) or high altitude cerebral edema (HACE), which are potentially fatal.
People have different susceptibilities to altitude sickness; for some otherwise healthy people, acute mountain sickness (AMS) can begin to appear at around 2000 meters (6,500 ft) above sea level, such as at many mountain ski resorts, equivalent to a pressure of 80 kPa. AMS is the most frequent type of altitude sickness encountered. Symptoms often manifest themselves six to ten hours after ascent and generally subside in one to two days, but they occasionally develop into the more serious conditions. Symptoms include headache, fatigue, stomach illness, dizziness, and sleep disturbance. Exertion aggravates the symptoms.
The Lake Louise assessment system of AMS is based on a self-report questionnaire as well as a quick clinical assessment.
Those individuals with the lowest initial partial pressure of end-tidal Pco¬2 (the lowest concentration of CO2 at the end of the respiratory cycle) as a measure of a higher alveolar ventilation, as well as individuals with a corresponding high oxygen saturation levels tend to have a lower incidence of Acute Mountain Sickness than those with high end-tidal Pco¬2 and low oxygen saturation levels.
Headaches are the primary symptom used to diagnose altitude sickness, although a headache is also a symptom of dehydration. A headache occurring at an altitude above 2,400 metres (8,000 feet = 76 kPa), combined with any one or more of the following symptoms, may indicate altitude sickness:
Lack of appetite, nausea, or vomiting
Fatigue or weakness
Dizziness or lightheadedness
Pins and needles
Shortness of breath upon exertion
Persistent rapid pulse
Peripheral edema (swelling of hands, feet, and face).
 Severe symptomsSymptoms that may indicate life-threatening altitude sickness include:
Pulmonary edema (fluid in the lungs):
Symptoms similar to bronchitis
Persistent dry cough
Shortness of breath even when resting
Cerebral edema (swelling of the brain):
Headache that does not respond to analgesics
Gradual loss of consciousness
The most serious symptoms of altitude sickness arise from edema (fluid accumulation in the tissues of the body). At very high altitude, humans can get either high altitude pulmonary edema (HAPE), or high altitude cerebral edema (HACE). The physiological cause of altitude-induced edema is not conclusively established. It is currently believed, however, that HACE is caused by local vasodilation of cerebral blood vessels in response to hypoxia, resulting in greater blood flow and, consequently, greater capillary pressures. On the other hand, HAPE may be due to general vasoconstriction in the pulmonary circulation (normally a response to regional ventilation-perfusion mismatches) which, with constant or increased cardiac output, also leads to increases in capillary pressures. For those suffering HACE, dexamethasone may provide temporary relief from symptoms in order to keep descending under their own power.
HAPE can progress rapidly and is often fatal. Symptoms include fatigue, severe dyspnea at rest, and cough that is initially dry but may progress to produce pink, frothy sputum. Descent to lower altitudes alleviates the symptoms of HAPE.
HACE is a life threatening condition that can lead to coma or death. Symptoms include headache, fatigue, visual impairment, bladder dysfunction, bowel dysfunction, loss of coordination, paralysis on one side of the body, and confusion. Descent to lower altitudes may save those afflicted with HACE.
I saw a man almost die from severe altitude sickness. The surest way to become a statistic is to think it can't happen to you, which is what he did. When we found him he had been coughing up blood for two days and could not walk more than 10 feet without stopping to catch his breath and wheezing. He had just written his wife and infant daughter a good-bye letter. After he got flown out, his gear sat by the side of the trail as a reminder to us of what had happened earlier that week. The stories that people told us later in Lake City were all about people who had died because they either didn't know what altitude sickenss was, or didn't take the symptoms seriously until it was too late.
I'd rather be safe than sorry. More people die in the wilderness because they are under prepared, not over prepared. More people die because they aren't cautious, not too cautious. At the bottom of Engineer Pass outside Lake City is the decaying wreck of an International Scout that rolled down the hill because the driver thought it couldn't happen to him.