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(Running Time: 10:00)

Mountain climbing can be hazardous to your health. And with more and more adventurers participating in sports that take them to higher altitudes, the potential for disasters is increasing. In this episode, a German research team heads for the Alps to see if a test can predict who will adjust successfully to reduced levels of oxygen. Even though the volunteers are aware of the risks, the situation nearly turns fatal for one of them.

Curriculum Links
Mountain Climbing and Human Physiology
At High Altitiudes
For Further Thought



circulatory system,
respiratory system


blood cells,
human brain


aerobic breathing,
fitness, hypoxia

gas exchange,
lung capacity,


Two thousand years ago, Chinese travelers climbing the Himalayas called them the "Headache Mountains." And little wonder. The high peaks of the Himalayas have caused more than a few headaches for even the most experienced mountain climbers over the centuries.

The ancient Chinese who ascended those lofty peaks had one advantage modern travelers often do not: climbers in previous centuries were forced to acclimate slowly to any change in height, since they could not be flown in to a mountain resort and expect to be on the slopes or out hiking on the same day.

In a modern scenario, tourists fly from their homes at sea level to a mountain resort at 7,000 or 8,000 feet. The adventurous traveler then decides to take a tram or hike to the ski slopes, or climb a mountain trail, which might be closer to 9,000 or 10,000 feet. By nightfall, the traveler may experience severe headaches, shortness of breath, nausea, mental confusion and great fatigue.

This form of altitude sickness is known as acute mountain sickness. It can occur when people accustomed to living at sea level ascend to altitudes higher than 8,000 feet too rapidly for the body to adjust. At higher altitudes, changes in the atmospheric air pressure cause oxygen levels to drop. Mountain sickness is the body's response to falling concentrations of oxygen. It is remedied by rest or descent. Mountain Climber
Not everyone who travels above 8,000 feet will experience symptoms of acute mountain sickness. It was once thought that more physically fit people would have an easier time adjusting to altitude. But that is not always the case, as you see on FRONTIERS when scientists try to predict who will experience the more severe form of mountain sickness. Some people are not as susceptible to any form of mountain sickness.

The case of mountain sickness in this episode of FRONTIERS is more extreme than that experienced by the occasional traveler. This more dangerous form of mountain sickness is high-altitude pulmonary edema, which can be fatal. Experienced climbers and skiers know that the key to preventing problems at altitude is to climb slowly, allowing the body to acclimate. As a rule of thumb, climbers can avoid perils by ascending 2,000 feet a day above 7,000 feet and by climbing at a comfortable pace, allowing time for rest.


Even altitudes of 5,000 feet can literally take your breath away. If you live at an elevation of less than 3,000 feet, be aware that a rapid change in altitude can occasionally cause problems. Altitude sickness is highly unpredictable and can strike people in the best of health. Be aware of these symptoms:

  • listlessness, drowsiness, apathy
  • prolonged or severe headache, extreme thirst
  • sleep disturbances, mental confusion
  • slowed reflexes, fatigue

To cope with altitude sickness and its potentially unpleasant or dangerous effects when hiking, skiing or snowboarding, acclimate yourself slowly, drink plenty of water and avoid vigorous exercise until you've adjusted to the higher elevation.


  • What is the altitude where you live?
  • Compare the atmospheric pressures at various altitudes, from sea level to 29,0008.
  • Investigate the effects on the body of deep-sea diving at depths comparable to high altitudes. How are the "bends" like altitude sickness?
  • For more details on the physiology of the human body at high altitudes, see "Mountain Sickness" in the October 1992 issue of Scientific American.


Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.