What Happens at High Altitude?

HIgh altitude is considered to be above 5,200 feet, but most of the potentially serious problems do not occur until around 7,000 feet. As is the case with most situations, "an ounce of prevention is worth a pound of cure," so take the necessary precautions when planning a trip that will take you to high elevations.

Altitude Sickness

• Altitude sickness is not caused by the lack of oxygen at high altitudes, but the lack of oxygen that passes through the lungs and it into your blood. This is caused by the lower air pressure, which can decrease by as much as 40 percent above 8,000 feet. In a study done by Altitude Research, 44 percent of the people who traveled above 10,000 feet, a typical elevation for ski resorts, suffered from altitude sickness. Severe altitude sickness can cause pulmonary edema, water in the lungs, and even cerebral edema, water in the brain, both of which can be fatal. Mild symptoms include headache, nausea and fatigue.

Cold

• Hypothermia and frostbite are two major problems faced at high altitudes. Temperature falls about 3 degrees Fahrenheit for every 1,000 feet of elevation. Wind is also an important factor when at high altitudes, as the wind chill can quickly lower the temperature. Regular body temperature is 98.6 degrees. Hypothermia starts to set in at under 95 degrees, with signs like shivering, cold white extremities, slurring speech and confusion. Exhaustion and injury are the main causes. Frostbite can set in at temperatures below 25 degrees. Often it is difficult to detect because of the numbness that accompanies it. Warm, windproof clothing is the best protection.

Effects of the Sun

• As elevation increases, the atmosphere becomes thinner, offering less protection from the sun's UV rays than at ground level. Lower temperatures at higher altitudes, combined with less UV protection, make for a deceptive and dangerous combination. For every elevation gain of 1,000 feet, the sun's rays increase in intensity by 4 percent. The sun's rays also reflect off of snow, exacerbating the situation. It is important to use sunblock on exposed skin. Even if it is cloudy, the risk of sunburn is extreme. Wear a hat with a neck cover and sunglasses with UV protection.

Dehydration

• According to High Altitude Living, dehydration is the cause of more illness than lack of oxygen at low to medium altitudes. Signs of dehydration can be similar to those of altitude sickness, including lack of perspiration, dizziness and nausea.

  At 6,000 feet, you exhale and perspire twice as much as at sea level. Also, air pressure is lower at higher altitudes, meaning water evaporates more quickly from the skin and lungs. Humidity, too, is lower, which accelerates evaporation. When hiking at high altitudes, take twice as much water as you would at low altitudes.