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Into Thin Air...

gflaherty's picture

            A hobby that is as dangerous as it is exhilarating is that of mountain climbing.  From Mount Mckinley, to K2, to Everest, there many hazards that lay as obstacles between a climber and the summit.  One major and constant hazard is the role that high altitude plays on the physiology of the body. The effects of high altitude are responsible for a large amount of the deaths that occur while climbing Everest [2].  Of course, there is difficulty breathing as “Climber and filmmaker David Breashears…[describes climbing]… even with bottled oxygen, as equivalent to ‘running on a treadmill and breathing through a straw’” [2].  Yet, in addition to the direct effects of the air, there are several illnesses that can be deadly.

            Altitude sickness has varying symptoms in each person and is altitude dependent.  Mean that climbers are more than likely to succumb to altitude sickness once they cross the 8,000ft altitude [2].  The symptoms increase in severity as the climber continues to ascend. Over 25,000 feet is most commonly referred to as the death zone [2].  Contrary to popular belief, the air at sea level and the air at high altitudes both contain twenty-one percent oxygen [2].  The thinness of the high altitude air is due to the fact that the air is less dense- the molecules are spread further apart due to low pressure in the atmosphere, therefore the air is not as rich[2].  Air at sea level is about fifteen pounds per square inch, making it easier for oxygen molecules to pass through selectively permeable membranes in the lungs and enter the blood stream[3].  The deceased pressure makes it harder for there to be an interaction between the oxygen molecules and the membrane.  The characteristics of high altitude air make people prone to becoming ill.

            The onset of high altitude effects are known collectively as Acute Mountain Sickness (AMS).  The initial symptoms of altitude sickness are increased breathing rate and increased heart rate [2].  Because oxygen becomes harder to access, the body adapts by breathing more to try to increase the number of oxygen molecules in the system. As a climber ascends, their blood becomes thicker which can significantly raise their chances of blood clots or having a stroke [2].  Other symptoms of hypoxia include a decreased appetite and sense of thirst and insomnia [2].  Although these may seem less deleterious than the significant changes in breathing and heart rates, a loss of appetite and thirst can be deadly. Those that encounter AMS are likely to be serious climbers on physicallytaxing expeditions.  Therefore,eating and staying hydrated are key to staying safe and healthy on a mountain.  A climber that starts to experience AMS, is likely to become malnourished and dehydrated and therefore exacerbate their symptoms.

            More severe than AMS, High-Altitude Pulmonary Edema (HAPE) is defined as a gathering of fluid in the lungs.  HAPE isextremely fatal and only worsens with increased altitude.  Unless a climber descends in a timely manner they will literally drown in their own ‘internal fluid’ [2].  HAPE symptoms include shortness of breath even at rest, fatigue, sense of suffocation, frailty, and a constant cough that brings up fluid [4].

HAPE can also result in a sense of confusion and irrational behavior pattern [4].  HAPE marks the beginning the beginning of an increase in abnormal behavior that demonstrates the consequences that high altitude has on the central nervous system.  Another indicator of HAPE is Cyanosis, which is when the skin turns a bluish hue [1].  Those whose high-altitude sickness evolves into HAPE have a high chance of heart failure due to the added pressure put onto the chest cavity [3]. Anyone experiencing these symptoms should be brought to a low altitude immediately before their condition worsens.

            High-Altitude Cerebral Edema (HACE) is defined as a swelling of the brain due to the fact that the body compensates for lack of oxygen by increasing the circulation of blood [2].  It is known that, “HACE may progress very rapidly and is more sever than HAPE.  The swelling of the brain results in“…loss of coordination and mental deterioration…” [2].  The central nervous system, at this point is reacting to sensory inputs that never actually were inputted.  Climbers “…have been known to chat with imaginary companions, see strange visions, and lose touch with reality…” [2].  The pressure put on the cerebrum results in decreasing levels of consciousness and these decreasing levels of consciousness manifest in disorientation, loss of memory, hallucinations, psychotic behavior and coma [4].  These symptoms seem dangerous enough on their own, but to see these symptoms in a person attempting to climb to 29,00 feet means that they are in serious danger of having a psychotic episode on a particularly steep section of the climb, or becoming serious disoriented and falling right off the side of the mountain. These severe symptoms of HACE are usually first seen after several days to a week at high altitude [4].

            Climber who attempt Everest are at high altitudes for months before actually summiting.  The objective of this is acclimatization.  If and when acclimatization is allowed to occur, the body responds to altitude changes by increase its red blood cell count in order for the blood be prepared carry more oxygen [3].  The lungs also tend toincrease in size in order to increase the surface area exposed to the air andtry to capture more oxygen molecules [3]. Although any form of altitude sickness can occur without warning, acclimatization allows for this adaptation to happen and thus minimalize symptoms of high altitude.  The adaptation process that takes place is actually one that is sought after because, “Upon returning to sea level after successful acclimatization to high altitude, the  body usually hasmore red blood cells and greater lung expansion capacity than needed.  Since this provides athletes in endurance sports with a competitive advantage, the U.S. maintains an Olympic training center in the mountains of Colorado” [3].  When done in proper and safe conditions, hypoxia, a generalized lack of oxygen, can have a slightly beneficial outcome.


Works Cited

[1] “Adjustments to Altitude”

[2]  “Altitude aMajor Challenge to Climbers”

[3]  “Adaptingto High Altitude”

[4] “Acclimatization and Illness”



Paul Grobstein's picture

Exhilaration and hypoxia

A "beneficial outcome"? "exhilarating"? Is that directly attributable to hypoxia? Interesting issue.