Death zone

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Death zone

The death zone, in mountaineering

Mountaineering

Mountaineering is the sport, hobby or profession of walking, hiking, trekking and climbing up mountains. It is also sometimes known as alpinism, particularly in Europe....
, refers to altitude

Altitude

Altitude has multiple uses depending on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object....
s above a certain point where the amount of oxygen

Oxygen

Human

A human being, also human or man, is a member of a species of bipedalism primates in the family Hominidae . Mitochondrial DNA evidence indicates that modern humans originated in east Africa about 200,000 years ago....
life. The point is generally tagged as between . Many deaths in high-altitude mountaineering have been caused by the effects of the death zone, either directly (loss of vital functions) or indirectly (wrong decisions made under stress, physical weakening leading to accidents).

death zone usually refers to the highest peak on earth, Mount Everest

Mount Everest

Mount Everest, also called Sagarmatha or Chomolungma, Qomolangma or Zhumulangma is the List of highest mountains on Earth, as measured by the height of its Topographical summit above sea level, which is ....
, and specifically the final few thousands of feet below the summit. The human body

Human body

The human body is the entire physical and mental structure of a human organism, and consists of a head, neck, torso, two arms and two legs.By the time the human reaches adulthood, the body consists of close to 10 trillion Cell , the basic unit of life....
functions at its best at sea level

Sea level

Mean sea level is the average height of the sea, with reference to a suitable reference surface. Defining the reference level , however, involves complex measurement, and accurately determining MSL can prove difficult....
, where the atmospheric pressure

Atmospheric pressure

Atmospheric pressure is sometimes defined as the force per unit area exerted against a surface by the weight of air above that surface at any given point in the Earth's atmosphere....
is measured at 1 atm

Atmosphere (unit)

The standard atmosphere is an international reference pressure defined as 101,325 Pascal and formerly used as unit of pressure . For practical purposes it has been replaced by the Bar which is 100,000 Pa....
.

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Encyclopedia

The death zone, in mountaineering

Mountaineering

Altitude

Oxygen

Human

Physiological background

The death zone usually refers to the highest peak on earth, Mount Everest

Mount Everest

Human body

Sea level

Atmospheric pressure

Atmosphere (unit)

Hemoglobin

Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of vertebrates, and the tissues of some invertebrates....
(the oxygen-binding red pigment in red blood cells) is saturated with oxygen

Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
(nearly 100 %) at that air pressure.

At higher altitudes, the air pressure drops and so does the amount of available oxygen. At (height of Mount Everest

Mount Everest

Mount Everest, also called Sagarmatha or Chomolungma, Qomolangma or Zhumulangma is the List of highest mountains on Earth, as measured by the height of its Topographical summit above sea level, which is ....
base camp), the amount of oxygen is only half that at sea level. At (summit of Mount Everest), only one-third as much is available. When the partial pressure

Partial pressure

In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. The total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture....
of oxygen drops, the human body tries to compensate by a process known as altitude acclimatization. Additional red blood cells are manufactured, the heart beats faster, non-essential body functions are temporarily shut down, food digestion efficiency declines (as the body shuts the digestive system down) and one breathes

Respiratory system

A respiratory system?s function is to allow gas exchange. The space between the alveoli and the capillaries, the anatomy or structure of the exchange system, and the precise physiological uses of the exchanged gases vary depending on the organism....
more deeply and more frequently. However, acclimatization cannot take place immediately – in fact, it takes place over a period of days or even weeks. Failure to acclimatize may result in altitude sickness

Altitude sickness

Altitude sickness, also known as acute mountain sickness , altitude illness, or soroche, is a pathological condition that is caused by acute exposure to low air pressure ....
, including high altitude pulmonary edema

High Altitude Pulmonary Edema

High altitude pulmonary edema is a life-threatening form of non-cardiogenic pulmonary edema that occurs in otherwise healthy mountaineers at altitudes above 2,500 meters ....
(HAPE) or cerebral edema

Cerebral edema

Cerebral edema is an excess accumulation of water in the intracellular and/or extracellular spaces of the brain....
(HACE).

At extreme altitudes (above ), sleeping becomes very difficult, digesting food is near-impossible, and the risk of HAPE or HACE increases greatly.

Finally, in the "death zone" at and higher, no human body can acclimatize. The body uses up its store of oxygen faster than it can be replenished. An extended stay in the zone without supplementary oxygen will result in deterioration of body functions, loss of consciousness and, ultimately, death.

Death zone

Physiological background

See also