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Altitude - FAQs
- What is considered high altitude?
- What causes altitude illness?
- What can be done to prevent Altitude Sickness?
- If possible, don't fly or drive directly to high altitude.
- If you do fly or drive, do not over-exert yourself for the first 24 hours.
- The acclimatization process is inhibited by dehydration, over-exertion, and alcohol and other depressant drugs.
- Take it easy; don't over-exert yourself when you first get up to altitude. Light activity during the day is better than sleeping because respiration decreases during sleep, exacerbating the symptoms.
- Stay properly hydrated. Acclimatization is often accompanied by fluid loss, so you need to drink lots of fluids to remain properly hydrated (at least 3-4 quarts per day). Urine output should be copious and clear.
- Avoid tobacco and alcohol and other depressant drugs including barbiturates, tranquilizers, and sleeping pills. These depressants further decrease the respiratory drive during sleep resulting in a worsening of the symptoms.
- Eat a high carbohydrate diet (more than 70% of your calories from carbohydrates) while at altitude.
- Keep in mind that different people will acclimatize at different rates.
Altitude is defined on the following scale: High (8,000 - 12,000 feet [2,438 - 3,658 meters]), Very High (12,000 - 18,000 feet [3,658 - 5,487 meters]), and Extremely High (18,000+ feet [5,500+ meters]). There are no specific factors such as age, sex, or physical condition that correlate with susceptibility to altitude sickness. Some people get it, some people don't, and some people are more susceptible than others. If you haven't been to high altitude before, it is important to be cautious. If you have been at high altitude before without problems, you can probably return to that altitude without problems as long as you are properly acclimatized.
The concentration of oxygen at sea level is about 21% and the barometric pressure averages 760 mmHg. As altitude increases, the concentration remains the same but the number of oxygen molecules per breath is reduced. At 12,000 feet (3,658 meters) the barometric pressure is only 483 mmHg, so there are roughly 40% fewer oxygen molecules per breath. In order to properly oxygenate the body, your breathing rate (even while at rest) has to increase. This extra ventilation increases the oxygen content in the blood, but not to sea level concentrations. Since the amount of oxygen required for activity is the same, the body must adjust to having less oxygen. SOURCE-Princeton
Prevention of altitude illnesses falls into two categories: Proper acclimatization and preventive medications. Below are a few basic guidelines for proper acclimatization: