There are many reasons why people ascend to high altitudes, from travel, leisure, and sport to making permanent homes at altitude. Some people are more susceptible to altitude sickness, a condition caused by exposure to low oxygen levels at high altitudes.
Ascending to high altitudes subjects the body to several significant changes, including decreases in temperature and ambient humidity, to a drop in barometric pressure (air pressure). The body can take some time to make the adjustments necessary to survive comfortably at altitude.
Altitudes above 8000 feet pose significant risks to the body and may result in dangerous symptoms from the ascent. Any symptoms experienced at high altitude can quickly develop into life-threatening problems and should not be dismissed.