High Elevations and the Blood: The Respiratory System

Respiratory System: High Elevations and the Blood

Why do people experience shortness of breath at high altitudes? Why does tendency clear off after several days?

Humans experience two main types of environmental stresses at high altitudes. First, they experience rapid dehydration as a result of the strong winds and low humidity; and secondly, they could have shortness of breath as a direct result of the low air pressure (Boga, 1997). The estimated altitude of the Alps is 15,700 ft above sea level. The altitude of the U.S. is commonly taken at sea level owing the effect of the Atlantic Ocean. Air pressure and the concentration of oxygen in the air both decrease with increases in altitude, particularly because at high altitudes, the air is thinner and the molecules are farther apart. At sea level, the air pressure happens to be at around 14.7 pounds; at 10,000 feet, it is around ten pounds; and at 18,000 feet, it is believed to be between 5 and 7 pounds (Boga, 1997). This means that the air pressure on the Alps falls anywhere between 7 and 10 pounds (almost half the pressure at sea level). The moderate air pressure at sea level makes it relatively easy for oxygen to pass through the selectively permeable membrane of the lungs into the blood. On the Alps, however, the low air pressure inhibits the smooth flow of oxygen into the blood, which essentially means that the blood transports lower levels of oxygen than its normal load at sea level. Boga (1997) expresses that at such high altitudes, the blood could carry almost 15% less than its normal oxygen load. These lower levels of oxygen cause shortness of breath and other unpleasant symptoms such as nausea and fatigue as the body attempts to "restrict blood flow to the organs in favor of the more needy muscles" (Boga, 1997, p. 114).