Altitude Illness 

Photo of mountain rangeAt altitude, there is decreased availability of oxygen in ambient (surrounding) air. This lowers the oxygen supply to the body, which can lead to altitude illnesses and reduced physical and mental performance. Altitude exposure may also increase the likelihood of other environmental injuries (e.g., cold injuries) or worsen pre-existing medical conditions.






 Meters (m) / Feet (ft)

 Effects of Acute Altitude Exposure


Sea Level – 1200m / 4000 ft



1200-2400m / 4000-7870 ft

Mild altitude illness and decreased performance may occur


2400-4000m / 7870-13,125 ft

Altitude illness and performance decrements are more common and greater

Very High

4000-5500m / 13,125-18,000 ft

Altitude illness and decreased performance is the rule


5500m / 18,000 ft - and higher

With acclimatization, humans can function for short periods of time


Altitude Effects on the Human Body

Common effects of altitude exposure on the human body, products to avoid at high altitudes, acclimatization

Altitude Illness and Environmental Threats

Information on altitude illness and environmental threats.