National Renewable Energy Laboratory

Visiting NREL

Altitude Information

Altitude illness is caused by the lack of oxygen in our thin mountain air. Altitude illness can affect anyone, regardless of age or physical condition in altitudes above 6,000 feet. The altitude illness seen most commonly is:

Acute Mountain Sickness (A.M.S.)

Acute Mountain Sickness is a mild form of altitude sickness that effects 20% to 30% of visitors to Colorado. The symptoms include headache, nausea, vomiting, and trouble sleeping. A.M.S. looks and feels like the flu. Most people experience the symptoms of A.M.S. within the first three days of arrival. The symptoms usually go away by the fourth day.

The incidence and severity of A.M.S. are related to altitude, speed of ascent, physical exertion, and prior acclimatization. Some people are particularly susceptible to A.M.S. and experience similar episodes with each exposure. Symptoms of headache, shortness of breath, anorexia or nausea, weakness, dyspnea, and flu-like malaise may begin 6 to 48 hours after ascent.

Treatment of A.M.S.

Most people with mild A.M.S. get better with no treatment at all. People with moderate or severe symptoms should see a doctor. Things that help:

1. Before your trip, maintain a good work/rest cycle, avoiding excessive work hours and last minute packing.
   
   
2. Avoid alcohol, sleeping pills, or narcotics; they may decrease ventilation, intensify hypoxemia, and make symptoms worse.
   
   
3. Drink plenty of fluids.
   
   
4. Eat high-carbohydrate foods (rice, pasta, cereal) while avoiding fatty foods.
   
   
5. Avoid heavy exercise. Mild exercise is okay.
   
   
6. Certain prescription drugs, such as Diamox (acetazolamide) can help prevention and treatment of A.M.S. by allowing you to breathe deeper and faster. As always, consult your physician before taking any medication. Your doctor might recommend other treatments, such as home oxygen.
   
   
7. If nothing else works, you can return to lower altitude.

Prevention of A.M.S.

People who get symptoms from high altitude can take several steps to prevent symptoms on their next visit to Colorado.

1. "Staging" or spending time at one altitude before heading to a higher altitude helps. If you are coming from sea level, it is better to spend the night in Denver or Colorado Springs before heading to a higher elevation. Take time to acclimate to each progressive change in elevation. This allows your body to adjust to the altitude and will help you adjust more quickly to higher altitudes later.
   
   
2. Do not over-do on your first day or two.
   
   
3. Physical conditioning at sea level does not help.

Conclusion

Rapid ascent to high altitude can be uncomfortable for many people and dangerous for some. Headache and other symptoms of acute mountain sickness may be prevented by gradual ascent or with certain medications, if your doctor prescribes them. Pulmonary edema occurs in a small percentage of people who quickly ascend to elevations above 8,000 feet. Those patients need to see a physician for oxygen therapy and descend to lower altitude.