- Also called:
- mountain sickness
altitude sickness
-
What is altitude sickness?
Altitude sickness, also known as acute mountain sickness, is a reaction to moving from a low altitude to altitudes above 8,000 feet (2,400 meters). French physiologist Paul Bert showed in 1878 that the symptoms result from a deficiency of oxygen in body tissues.
Symptoms include respiratory issues, such as shortness of breath; mental and muscular issues, such as dizziness and fatigue; cardiac issues, such as chest pain; and gastrointestinal issues, such as nausea and vomiting. The main protection against altitude sickness in aircraft is cabin air pressure. Mountain climbers will often use a mix of pure oxygen and air.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What causes altitude sickness to happen?
Altitude sickness, also known as acute mountain sickness, is triggered by moving from a low altitude to 8,000 feet (2,400 meters) or higher. The reduction in barometric pressure at higher altitudes results in a lower partial pressure of oxygen in the lungs. Consequently, less oxygen is absorbed by red blood cells and transported to the body's tissues, causing a deficiency of oxygen in the arterial blood.
The body attempts to adjust through acclimatization, which involves deeper breathing to enhance oxygen pressure. The body may also increase red blood cell production to improve oxygen transport to tissues.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What are common symptoms of altitude sickness?
Altitude sickness, also known as acute mountain sickness, is a reaction to a change from low-altitude environments to altitudes above 8,000 feet (2,400 meters). Symptoms usually occur within 6 hours to 4 days after arrival at a high altitude and disappear within 2 to 5 days as acclimatization occurs.
Common symptoms include respiratory issues like shortness of breath, deeper and more rapid breathing, and mental or muscular symptoms such as weakness, fatigue, dizziness, headache, and sleeplessness. Cardiac symptoms can include chest pain, palpitations, and irregular heartbeat, while gastrointestinal symptoms include nausea and vomiting.
3 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
Who is most at risk for altitude sickness?
People who ascend from sea level or low-altitude settings to elevations above 8,000 feet (2,400 meters) may experience altitude sickness. Mountain climbers, pilots, and people residing at high altitudes are most susceptible. The symptoms, which typically manifest within six hours to four days of arriving at a high altitude, include respiratory issues, such as shortness of breath; mental and muscular problems, such as fatigue and dizziness; cardiac symptoms, such as chest pain; and gastrointestinal issues, such as nausea. Although most people gradually recover as they adapt to the low atmospheric pressure of high altitude, some persons experience a reaction that can be severe and, unless they return to low altitude, possibly fatal.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How can altitude sickness be prevented?
Altitude sickness is an acute reaction to altitudes above 8,000 feet (2,400 meters), where the air is thinner and breathable oxygen decreases.
To prevent altitude sickness:
* Ensure aircraft cabins have pressurized air.
* Mountain climbers can use a mixture of pure oxygen and air.
* Two to three days before going to a high altitude, consider using the diuretic acetazolamide.Humans adjust to the fall in oxygen pressure through acclimatization, which commences from the time of exposure to high altitudes.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What should you do if someone shows serious signs of altitude sickness?
Altitude sickness can range from mild to life-threatening. Symptoms include shortness of breath, fatigue, dizziness, nausea, and rapid breathing.
If someone exhibits serious signs of altitude sickness, immediate descent to a lower altitude is crucial. Administering oxygen can help alleviate symptoms while evacuating to a lower area. In cases of high-altitude pulmonary edema (HAPE), where fluid accumulates in the lungs, oxygen administration and prompt evacuation are essential.
1 Britannica SourceCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
altitude sickness, acute reaction to a change from sea level or other low-altitude environments to altitudes above 8,000 feet (2,400 metres). Altitude sickness was recognized as early as the 16th century. In 1878 French physiologist Paul Bert demonstrated that the symptoms of altitude sickness are the result of a deficiency of oxygen in the tissues of the body. Mountain climbers, pilots, and persons living at high altitudes are the most likely to be affected.
The interactive presents a series of charts showing the deaths on Mount Everest between 1953 and 2023. Altitude sickness, or acute mountain sickness, is listed as the cause of a significant fraction of all deaths on the mountain.
The symptoms of acute altitude sickness fall into four main categories: (1) respiratory symptoms such as shortness of breath upon exertion, and deeper and more rapid breathing; (2) mental or muscular symptoms such as weakness, fatigue, dizziness, lassitude, headache, sleeplessness, decreased mental acuity, decreased muscular coordination, and impaired sight and hearing; (3) cardiac symptoms such as pain in the chest, palpitations, and irregular heartbeat; and (4) gastrointestinal symptoms such as nausea and vomiting. The symptoms usually occur within six hours to four days after arrival at high altitude and disappear within two to five days as acclimatization occurs. Although most people gradually recover as they adapt to the low atmospheric pressure of high altitude, some persons experience a reaction that can be severe and, unless they return to low altitude, possibly fatal.
" height="20" alt="HEW Logo">
At higher altitudes, the air becomes thinner and the amount of breathable oxygen decreases. The lower barometric pressures of high altitudes lead to a lower partial pressure of oxygen in the alveoli, or air sacs in the lungs, which in turn decreases the amount of oxygen absorbed from the alveoli by red blood cells for transport to the body’s tissues. The resulting insufficiency of oxygen in the arterial blood supply causes the characteristic symptoms of altitude sickness. The main protection against altitude sickness in aircraft is the use of pressurized air in cabins. Mountain climbers often use a mixture of pure oxygen and air to relieve altitude sickness while climbing high mountains. In addition, the prophylactic use of the diuretic acetazolamide initiated two to three days before ascent may prevent or mitigate acute altitude sickness.
A more serious type of altitude sickness, high altitude pulmonary edema (HAPE), occurs rarely among newcomers to altitude but more often affects those who have already become acclimated to high elevations and are returning after several days at sea level. In pulmonary edema, fluid accumulates in the lungs and prevents the victim from obtaining sufficient oxygen. The symptoms are quickly reversed when oxygen is given and the individual is evacuated to a lower area.