Once you have reached elevations of over about 8,000 feet, your body has reached alien territory. Unless you are one of the relatively small percentage of the world’s population that has adapted to these heights, you will notice the decrease in oxygen. This can lead to altitude sickness, which may be as minor as nausea, headache, and dizziness, or to something far worse.
The human body is accustomed to functioning at certain oxygen levels. Every part of the body relies on oxygen, and it becomes reliant on a certain amount. When you reach areas where oxygen levels drop, and the air become thin, the body reacts to its new environment. The brain, lungs, and other organs are suddenly feeling deprived, and they let you know it. If you are lucky, the illness that you develop will be minor, and last for a short time. But, as you climb to even higher elevations, the further decrease can cause edemas, that affect the lungs or brain, and may even become fatal.
Tourists, going to areas of the world where they will be staying at high elevations are advised to take it slowly, and gradually become acclimated one step at a time. This may take several days, as they travel higher in elevation, resting, and allowing their bodies to adjust. By going slowly, they can sometimes avoid altitude sickness altogether. Obviously, people who live everyday of their lives at sea level or at very low elevations will have more to adjust too than those who live in mountainous regions.
Even seasoned mountain climbers find it necessary to stop at intervals on their climb to allow their bodies to get used to the thin air. Plunging into a high altitude situation sometimes leads to severe consequences, disorientation, and possibly death. And, there is no sure way to know how your body will react until you actually put it to the test.
For the most part, having mild symptoms of high altitude sickness doesn’t mean that you have to abandon your hike or vacation and go back down to sea level. Given time, your body will adjust to its new environment. However, it is recommended that if you have severe symptoms, such as disorientation, you should retreat to a lower altitude. In some cases, people with certain chronic illnesses will not be able to safely climb to high altitudes, regardless of how carefully they try to acclimate themselves.