The pure air at high altitudes is less rich in oxygen than air at sea level. Because the air gets lighter the higher you climb, you quickly get out of breath when you go mountain-climbing if you not used to it.
When you breathe in, you fill your lungs with a certain amount of air. A fifth of this air consists of oxygen, which supports life. Part of the oxygen is carried around the body by the red corpuscles in the blood. When you breathe out, you expel air, which still contains a little oxygen, because the blood has not been able to use it all.
Since the air at high altitudes has less oxygen than the air at sea level, the body produces more red corpuscles, in order to retain as much oxygen as possible.
The number of red corpuscles, however, cannot be increased immediately. The body needs time to produce them. A period of eight to ten days is required to make a sufficient number. This increase is one of the chief ways in which we accustom, or adapt, ourselves to higher altitudes. The Indian of South America, who live on the high plateaux of the Andes, have twice the amount of red corpuscles compared with people living in the coastal regions.
A holiday at high altitude, at 1000 to 1200 m (approximately 3300 to 3900 ft), say, automatically increases the number of red corpuscles. This can only be good for the health. In addition, a ‘lungful of air’, far from the city dust, cleanses the lungs.
People used to say that mountain air ‘stimulates the blood’. This was obviously because the air favoured the production of red corpuscles and put those, which were stock-piled in the organs, into circulation.
It should be noted, however, that sick people should keep to moderate altitudes-a sickly body risks damage above 2000 m (6500 ft). The shock would be too great for the body. Any activity affecting the circulatory system must be carried out under medical supervision. Remember, a holiday at high altitude is only good for you if you regulate the activity. After at least a month’s physical training, you probably could race down a ski run without any danger, especially if you have been sensible enough to wait until the body has adapted to its new environment, before attempting any feats.
The same applies to summer activities: moderation is the word for a holiday that will do you good.