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MMA Memo #162

Medical and Physiological Considerations for a High-Altitude MMA Site

P.J.Napier [1], J.B.West (School of Medicine, UCSD, San Diego)

October 14, 1996

Keywords: medical, physiology, altitude, oxygen

At the 5000 m altitude of the proposed MMA site in Chile the partial pressure of oxygen of the inspired gas in the lung is only 53% of its sea-level value. The resulting hypoxia causes a number of medical and physiological effects which must be considered in the planning of the instrument. In this report some of the existing studies of these effects are reviewed in order to predict, where possible, their severity in the MMA situation. An operating scenario is proposed which makes the construction and operation of the MMA feasible at this high elevation. The two key features of this scenario are the establishment of a low altitude Operations Support Base (OSB) at 2440 m and the oxygen enrichment of the air inside the buildings on the 5000 m site. Workers will sleep at the OSB and complete as much work as possible there, making the 1.25 hr drive to the site only when necessary. Workers who start to develop any of the high altitude illnesses can be immediately taken down to the OSB where the condition will quickly reverse. The oxygen in the site buildings will be enriched to 26 % oxygen, providing an effective working altitude for indoors workers of 3500 m (11500 ft). Although many outdoor workers will acclimatize sufficiently so that supplemental oxygen is not required, those workers who require it will be supplied with portable oxygen from a lightweight tank feeding nasal cannulas. The successful operation of high altitude facilities of comparable complexity to the MMA provides reassurance that the proposed MMA operation is feasible. The complex of large telescopes at the Mauna Kea Observatory at 4215 m (13800 ft) are successfully operated and maintained by workers who, for the most part, commute daily from sea-level. Although the high altitude problems are somewhat worse at 5000 m than they are at 4215 m, the higher sleeping altitude of the MMA workers and the use of oxygen enrichment should make up for this difference. Large mines employing many hundreds of workers are now successfully operating in Chile at elevations up to 4600 m. These mines employ the most modern technology requiring a high level of technical ability from the workers. The technique of oxygen enrichment is now being used at these mines.

[1] NRAO Socorro

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Last modified: 09 December, 1999