Altitude sickness is caused by a lack of atmospheric pressure

Adventurous explorers can spend
months training prior to scaling
mountain peaks, but regardless of
fi tness level, high altitudes can take
a toll on the human body.
Between around 1,524 and 3,505
metres (5,000 and 11,500 feet) above
sea level is considered high altitude.
Most travellers will start to feel the
effects of high altitude sickness as they
attempt to acclimatise to the change in
atmosphere at these heights. The most
common symptom is shortness of
breath, which is due to a lack of
atmospheric pressure. At these heights,
air molecules are more dispersed, so
less oxygen can be inhaled. In order to
compensate, your heart rate will
increase and the body will produce
more red blood cells, making it easier to
transport oxygen around the body.
The low humidity levels at high
altitude can also cause moisture in the
skin and lungs to evaporate quicker, so
dehydration is a real threat. Your face,
legs and feet may start to swell as the
body attempts to retain fl uid by holding
more water and sodium in the kidneys.
Diffi culty sleeping is also common,
and symptoms of high altitude sickness
can get progressively worse the higher
you climb, including mood changes,
headaches, dizziness, nausea and loss
of appetite.