Altitude sickness, also known as acute mountain sickness (AMS), altitude illness, hypobaropathy, or soroche, is a pathological effect of high altitude on humans (and animals), caused by acute exposure to low air pressure (usually outdoors at high altitudes). It commonly occurs above 2,400 metres (approximately 8,000 feet).[1][2] Acute mountain sickness can progress to high altitude pulmonary edema (HAPE) or high altitude cerebral edema (HACE).[1][3]
The cause of altitude sickness is not understood.[1][4] It occurs in low atmospheric pressure conditions but not necessarily in low oxygen conditions at sea level pressure. Although treatable to some extent by the administration of oxygen, most of the symptoms do not appear to be caused by low oxygen, but rather by the low CO2 levels causing a rise in blood pH, alkalosis. The percentage of oxygen in air remains essentially constant with altitude at 21% up until 70,000 feet (21,330 m), but the air pressure (and therefore the number of oxygen molecules) drops as altitude increases — consequently, the available amount of oxygen to sustain mental and physical alertness decreases above 10,000 feet (3,050 m).[5][6] Altitude sickness usually does not affect persons traveling in aircraft because modern aircraft passenger compartments are pressurized at an air pressure equivalent to an altitude of 8,000 feet (2,440 m).
A related condition,[citation needed] occurring only after prolonged exposure to high altitude, is chronic mountain sickness, also known as Monge's disease.[7]
The cause of altitude sickness is not understood.[1][4] It occurs in low atmospheric pressure conditions but not necessarily in low oxygen conditions at sea level pressure. Although treatable to some extent by the administration of oxygen, most of the symptoms do not appear to be caused by low oxygen, but rather by the low CO2 levels causing a rise in blood pH, alkalosis. The percentage of oxygen in air remains essentially constant with altitude at 21% up until 70,000 feet (21,330 m), but the air pressure (and therefore the number of oxygen molecules) drops as altitude increases — consequently, the available amount of oxygen to sustain mental and physical alertness decreases above 10,000 feet (3,050 m).[5][6] Altitude sickness usually does not affect persons traveling in aircraft because modern aircraft passenger compartments are pressurized at an air pressure equivalent to an altitude of 8,000 feet (2,440 m).
A related condition,[citation needed] occurring only after prolonged exposure to high altitude, is chronic mountain sickness, also known as Monge's disease.[7]
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