Meters (m) / Feet
Effects of Acute Altitude
Sea Level – 1200m / 4000
1200-2400m / 4000-7870 ft
Mild altitude illness and decreased performance
2400-4000m / 7870-13,125 ft
Altitude illness and performance decrements are
more common and greater
4000-5500m / 13,125-18,000 ft
Altitude illness and decreased performance is
5500m / 18,000 ft and higher
With acclimatization, humans can function for
short periods of time
There are a number of illnesses of varying severity associated with altitude exposure. Symptoms to look for when working at altitude include:
- nausea and vomiting
- difficulty sleeping
- difficulty breathing, noisy breathing or wheezing, gurgling in the airway
- impaired mental status such as confusion, vivid hallucinations or disorientation
- a swaying upper body, especially when walking
- poor wound healing
- edema (a condition in which body tissues contain an excessive amount of tissue fluid)
- apnea (a temporary pause in breathing during sleep)
Many environmental threats commonly occur at altitude.
Cold Injuries: Cold injuries are a threat at high altitude. Frequent winds in mountain areas cause extremely low windchill. Because altitude exposures can result in poor judgment and decision-making, more cold injuries should be anticipated. Countermeasures for cold injuries include command emphasis on maintaining nutrition, drinking plenty of fluids, and dressing in multiple, loose layers. More information on cold injury prevention.
Injuries Caused by Sunlight: Solar radiation injuries caused by sunlight are likely at altitude due to increased ultraviolet (UV) radiation and reflection of light from snow and rock surfaces. Solar radiation injuries can be severe and occur with much shorter exposure at higher altitudes. Injuries caused by sunlight include:
- Sunburn may be more likely to occur on partly cloudy or overcast days when Soldiers may not be aware of the threat and do not take appropriate precautions. Use sun block (at least 30 SPF) to help prevent instances of sunburn.
- Snow blindness occurs when UV light is absorbed by the external parts of the eyes, such as the eyelids and cornea. There is no warning, aside from brightness, that sunburn-like eye damage is occurring. Damage can occur in just a few hours. Sunglasses or goggles with UV protection will prevent snow blindness. Sunglasses with side protectors are recommended.
Terrain Injuries: Soldiers should be aware of the dangers of avalanches and falls. Poor judgment at high altitude increases the risk of injury. The potential for being struck by lightning is also increased at higher altitudes, especially in areas above tree lines. Take shelter in solid-roofed structures or vehicles, stay low, and avoid tall structures or large metal objects.
Carbon Monoxide (CO) Poisoning is a frequent hazard and is caused by using stoves, combustion heaters, and engines in enclosed, poorly ventilated spaces. Cigarette smoking is another source of CO. To prevent CO poisoning, do not sleep in vehicles with engines running, do not cook inside tents, and do not sleep in tents without adequate ventilation while using combustion heaters or stoves. Seek fresh air immediately if CO poisoning is suspected.
Non-Battle Injuries: Altitude and cold can impair judgment and physical performance while maneuvering in rugged
terrain. Heavy clothing worn for protection against the cold and specialized equipment can also restrict movement. Non-battle injuries can be prevented by carefully observing safety procedures.
Infectious Diseases: Although there is generally a reduced threat of disease at high elevations, Soldiers should still take precautions to avoid diseases caused by insects, plants, and animals, as well as diseases transmitted from person to person. At moderate to high altitudes, insect-borne disease (from mosquitoes, ticks and flies) is common in most regions. In some areas, malaria-bearing mosquitoes range as high as 1800m. The threat of diseases transmitted from person to person is increased at higher, cold climates since Soldiers are more likely to gather together to keep warm.
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