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West, John B. High altitude limits of living things. High Alt Med Biol. 22:342–345, 2021.—The tolerance of animals to high altitude is generally limited by the low partial pressure of oxygen (PO2) in the air. Plant growth at high altitude is also limited but by different mechanisms. This article is a brief survey of the limiting factors of all living things. By a curious coincidence, the highest point on earth, that is Mt. Everest at 8,848 m, appears to be right at the limit of human tolerance to hypoxia. The altitude of the highest permanent human habitation, that is a town, is 5,100 m. This altitude is partly determined by the hypoxia, but also by economic factors. For other terrestrial mammals, birds, and insects, the highest altitudes for permanent habitation apparently belong to field mice (Phyllotis xanthopygus rupestris) and jumping spiders (Euophrys omnisuperstes) at about 6,700 m. Birds have been known to fly as high as 11,000 m although how much they are elevated by atmospheric updrafts is not clear. The record for animals for survival in extreme hypoxia is arguably held by the primitive invertebrate, the tardigrade (Hypsibius dujardini). This has been shown to tolerate the hard vacuum of space where the PO2 is essentially zero for many days. Less is known about the tolerance of plants to extreme altitude. However, vascular plants have been collected at >6,000 m in the Himalayas, and moss grows even higher. Lichens are very tolerant of severe hypoxia. There is evidence that global warming is increasing the highest altitudes at which plants can survive. [ABSTRACT FROM AUTHOR]

West, John B. Are permanent residents of high altitude fully adapted to their hypoxic environment? High Alt Med Biol. 18:135-139, 2017.-Millions of people live permanently at high altitude and many have been there for generations. It is sometimes claimed that these people have completely adapted to their environment, and certainly some remarkable genetic adaptations have recently been described. However there is now strong evidence that permanent residents are not completely adapted to the high altitude in the sense that they have fully compensated for the environmental hypoxia. By sea level standards, highlanders have severe chronic arterial hypoxemia. Furthermore, their maximum oxygen uptake increases if they descend, and recent measurements suggest that cognitive function is reduced in this population compared with a matched group at a lower altitude. Reproductive success is reduced at high altitude because neonatal mortality increases with altitude. The topic has recently gained importance because new technology enables the physiological altitude of permanent residents to be reduced by adding oxygen to the air of buildings on a large scale, a procedure known as oxygen conditioning. Its feasibility has been questioned, but in essence it is no different from air conditioning that is universally used to improve the well-being and productivity of millions of people in hot climates. Oxygen conditioning has the potential to do the same for permanent residents of high altitude. [ABSTRACT FROM AUTHOR]

The hypoxia of high altitude frequently affects cognitive function. Recent work has shown that high altitude impairs the neuropsychological function of children of school age when compared with a similar control group of children at low altitude. This implies that the learning process is compromised at high altitude. One option is to bus children down to a lower altitude for schooling, but this is generally impracticable. Recently the new technique of oxygen conditioning has been introduced. The procedure is similar to air conditioning except that instead of altering the temperature of the air, the oxygen concentration is increased, thus raising the PO2 in the inspired air of classrooms. The result is that the children are physiologically at a lower altitude. Just as in very hot or cold climates, it is now unacceptable to have schools that are not air conditioned; in the future the same may apply to schools at high altitude that are not oxygen conditioned. [ABSTRACT FROM AUTHOR]

AbstractDi Giulio C, and West JB. Angelo Moss's experiments at very low barometric pressures. High Alt Med Biol14:78–79, 2013.—In 1898, Angelo Mosso (1846–1910) used his low-pressure chambers to carry out some remarkable experiments that are not well known. Paul Bert (1833–1886) had previously demonstrated that the deleterious effects of high altitude were due to low Po2, but this conclusion was disputed by many of the eminent scientists of the day. Mosso believed that the physiological effects of high altitude were caused by a low Pco2(acapnia) and he made a series of low-pressure chamber experiments to test this. In some studies he added oxygen to the air in the chambers so that he could study the effects of extreme hypobaria; in one experiment he survived a barometric pressure of only 192 mm Hg equivalent to an altitude of about 10,800 m. Some of his experiments were observed by his daughter Mimí who wrote a colorful account in her book dedicated to her father “Un cercatore d'ignoto” (A seeker of the unknown). [ABSTRACT FROM AUTHOR]

An introduction to the journal is presented in which the editor discusses various articles within the issue on topics including exercise and altitude, study depicting impaired growth rate of bone in rats exposed to simulated high altitude and compromised liver function in rats at high altitude.