For many people, the dangers of mountain climbing include avalanches, rock slides and injury from a fall. Muscle soreness and heat exhaustion are usually concerns as well. However, climbing above the vertical limit should also be a concern on the list. Climbing too high can lead to three serious illnesses, two of which can be fatal if left untreated.
Acute mountain sickness (AMS), also known as altitude sickness, is caused by breathing air at altitudes between 2,500 to 3,500 meters, or about 8,000 to 11,482 feet. Above this range, many climbers begin to experience the side effects from breathing thinner air, which contains less oxygen. Because of this fact, 8,000 feet is sometimes considered a vertical limit -- an average height that a person can climb without the onset of AMS.
The early signs of AMS resemble flu-like symptoms, including nausea, fatigue and head pain. Other symptoms include dizziness, nosebleeds and insomnia. If a person remains in altitudes above about 8,000 feet, the sickness can progress to other illnesses such as high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). Both can be potentially fatal within a few hours. Symptoms of HAPE include fluid in the lungs -- pulmonary edema -- which causes breathlessness. HAPE victims often feel breathless even while they're resting. Other symptoms of HAPE include a high fever and frothy spit. HACE, on the other hand, is the most severe of the altitude illnesses because it causes fluid on the brain. The first signs of HACE include confusion, clumsiness and even uncharacteristic actions, such as violence.
The first treatment for altitude sickness should be to descend immediately. However, if that is not possible, medicine such as dexamethasone and acetazolamide can be administered. Inhaling oxygen from an oxygen tank can also slow the progression of AMS, HAPE and HACE. Still, descending is one of the most effective treatments for the illnesses. According to an article in the "British Medical Journal," all treatments should be accompanied by descension, and once treated, the survivability of AMS is high. According to the BMJ article, soldiers posted at high altitudes only have a death rate of 0.16 percent.
Careful climbers can avoid altitude sickness. One method of preventing AMS is to not ascend above 8,000 feet. Another is to climb no more than about 1,600 feet in a day. According to Altitude.org, the body can acclimate to thinner air if your ascent is slow. So climbing less than 1,600 feet per day gives the body an opportunity to adjust to the higher altitude. Still, other sources such as the UIAA Mountain Medicine Center and researchers at the University of California San Diego say that the maximum height or "vertical limit" that a human being can survive long-term is at about 6,000 meters or 19,685 feet. Ascending above 26,000 feet is generally considered dangerous, and is sometimes referred to as a "death zone."