Abstract
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The procedure is now being used extensively at high altitudes, including in some hotels, dormitories, mines, and telescopes. A notable example is the enormous Atacama Large Millimeter Array (ALMA) telescope situated at an altitude of 5000 m in north Chile where the number of people on the site was 400 at last count. Typically the oxygen is extracted from air using an oxygen generator that pumps air at high pressure across a synthetic zeolite. This preferentially adsorbs the nitrogen with the result that large amounts of 90%–95% oxygen can be obtained. Liquid oxygen can also be used if electrical power is not easily available for compressors. Raising the oxygen concentration too high can result in a fire hazard, but the safe limits have been clearly worked out by the National Fire Protection Association.
Recently it has become clear that there may be more applications for this technology. It is useful to draw an analogy between air conditioning and what can be called oxygen conditioning. Air conditioning alters the temperature and sometimes the humidity of the air in hot climates, and this has revolutionized living and working in many parts of the world. For someone who has worked briefly at the NASA Johnson Space Center near Houston during the summer, it is inconceivable that useful work could be carried out in the absence of air conditioning.
Oxygen conditioning is similar in many respects. However, rather than reducing the temperature of the air that is supplied to a building, oxygen conditioning increases the concentration of oxygen. It transpires that many of the engineering problems are similar. In both instances, compressors are extensively used, and large amounts of air are circulated. If the synthetic zeolite technique is employed, the only requirements for oxygen conditioning are compressors and electrical power. This is very similar to the requirements for air conditioning and the costs are probably comparable.
It is likely that oxygen conditioning could be used with advantage in many cities at high altitude. An example is Cerro de Pasco, which is the highest city in the world with a substantial population, in this case about 70,000 people. When the British physiologist Joseph Barcroft led a high altitude expedition to Cerro de Pasco in 1921–1922, he considered the effects of the high altitude on three groups of people there, and we shall do the same.
The first group consists of visitors to high altitude, that is, lowlanders who come from near sea level and are spending a few days or weeks at Cerro. These people will certainly feel the acute effects of the hypoxia and some of them will develop Acute Mountain Sickness. This can be alleviated by the oxygen conditioning which, in effect, reduces the environment to a lower altitude. In fact, at Cerro it is possible to safely reduce the equivalent altitude to near that of Denver, which of course is easily tolerated. This group of people will also probably have difficulties with sleeping, which typically causes periodic breathing in lowlanders. This will also be ameliorated by the oxygen conditioning.
However, in addition to this improvement in well-being, the oxygen conditioning will improve the function of the central nervous system. Newcomers to an altitude like this tend to make errors when they are doing any calculations, and they typically find it difficult to handle problem-solving. Barcroft referred to this as “bungling.” Thus there is strong evidence that the well-being and productivity of this group will be improved by oxygen conditioning.
The second group of people referred to by Barcroft were the sojourners. Cerro de Pasco is the site of an enormous open-cut mine, and the staff includes engineers and clerical workers who normally lived at low altitude but had been at Cerro for a few years. They were adamant that their work productivity was impaired by the altitude. Barcroft did not make any actual measurements on these people, but there is no reason to doubt their report. The same complaint has been made by other people living at a similar altitude for extended periods. These include health workers at Pheriche near Mt. Everest in Nepal.
The final group is the most interesting. These are the permanent residents of Cerro de Pasco who have been there for generations. Recent work reviewed by Yan (2014) indicates that even permanent residents of high altitude have some cognitive impairment compared with a comparable group at low altitude. This is a provocative finding that does not sit well with many people, but the evidence is convincing. A crucial question that has not yet been answered is whether these permanent residents will improve their cognitive ability if they go to a lower altitude. This would not be surprising on general biological grounds because the P
There are many sites at high altitude where oxygen conditioning would be helpful to at least the first two groups, and possibly the third group. Cerro de Pasco has been used as an example here because of its great altitude, and the historical connections with Barcroft. However, there are many other places in the world over 3500 m (11,480 ft) altitude with substantial populations. These include La Paz, El Alto, Potosi and Oruro in Bolivia, Lhasa, Litang, and Shigatse in China, and Juliaca and Puno in Peru. One site is hospitals where many patients would benefit from being transferred to what is, in effect, a lower altitude.
A particular example is the neonatal ward where newborn babies are being cared for. Since the time of the Spanish conquest, it has been appreciated that expectant mothers will benefit by going to lower altitudes to have their babies. Indeed, there is a strong correlation between neonatal mortality and altitude that has been described in Peru and many other parts of the world. Oxygen conditioning of the neonatal ward offers many advantages that women and their babies would have by going to a lower altitude, which is impossible for most because of economic factors.
Other facilities that could benefit from oxygen conditioning might include schools, dormitories, legislative offices, and conference rooms. Anywhere where important decisions are being made would be a candidate. For example, the dispatchers office in the mine where important decisions are being made all the time on where to send the loaders and trucks would probably benefit.
Oxygen conditioning on a large scale at high altitude is a new idea and only time will tell whether it is as advantageous as it appears to be. It will be very interesting to see how it pans out.