High Altitude

As altitude increases, the amount of oxygen available to be breathed decreases leading to low oxygen levels (hypoxia). The body will attempt to acclimatize to this lack of oxygen but may not be able to adequately compensate and Acute Mountain Sickness (AMS), High Altitude Cerebral Oedema (HACE) and High Altitude Pulmonary Oedema (HAPE) may develop. These conditions may be fatal.

At Altitudes of 1500-2500m exercise performance can be reduced but altitude sickness is rare.  Commercial aircraft are pressurised to an altitude equivalent of 1500-2500m.  At 2500m hypoxia occurs even at rest and symptoms of altitude sickness can be present.  At levels over 4000m acclimatization is always required to prevent illness.  At extreme altitude (>5500m) illness can occur despite acclimatization and sustained inhabitation is impossible.

Altitude Sickness can affect anyone and is not related to levels of physical fitness, age, and gender and can occur in people who have been to high altitudes without problems previously. It is impossible to predict who will be susceptible. It can however be exacerbated by rate of ascent, the altitude reached, strenuous exercise, ill health, dehydration, hypothermia, inadequate caloric intake, fatigue, alcohol and certain drugs.

Several other difficulties are associated with high altitude and mountaineering including avalanche, falls, hypothermia/cold injury and sun exposure to name a few.