ABSTRACT
It has been known since the time of Paul Bert and the publication of La Pression Barometrique that most of the deleterious effects of high altitude on humans are caused by hypoxia. This, in turn, is a direct result of the reduction in atmospheric pressure. Barometric pressure decreases with altitude because the higher we go, the less atmosphere there is above us pressing down by virtue of its weight. Vertically, the atmosphere can be divided based on temperature variations into the troposphere, the stratosphere, and regions above that. The limited applicability of the standard atmosphere is further clarified when we look at the relationship between barometric pressure and altitude for different latitudes. The variations of barometric pressure with latitude and season become particularly significant from a physiological point of view at extreme altitudes such as near the summit of Mount Everest.
