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HAPS: The Arctic Institute High Altitude Physioogy Study on Mount Logan


The Arctic Institute High Altitude Physiology Study on Mount Logan

Charles S. Houston, M.D.

THE small group of scientists who met in New York that fall day in 1966 were intrigued by the invitation “To talk about the feasibility of establishing a permanent laboratory at 18.000 feet to study the effects of high altitude on man.” The project had been proposed as a logical next step for the Icefield Ranges Research Program (IRRP) which the Arctic Institute of North America was conducting among several other programs in the Arctic. The Kluane Lake Base had been summer home since 1961 to scores of scientists studying the rocks and glaciers, the flora and fauna, weather, lakes and rivers in the wild and unspoiled southwestern tip of the Canadian Yukon, and a program in human physiology would be a natural addition. Kluane Lake is surrounded on the northeast and northwest by thousands of square miles of rolling hills, eroded valleys and lakes and tundra—almost untouched. To the southeast and southwest lie vast snowfields and glaciers studded with hundreds of great mountains which culminate in Mount Logan and Mount St. Elias.

Logan seemed ready-made for such a project. Its several summits surround three sides of an enormous bowl-shaped plateau some fifteen miles long and six miles wide, which slopes smoothly and gently from 19,000 to 11,000 feet before plunging over a precipice to glaciers six thousand feet below. We thought the plateau might be partially sheltered from very high winds by these surrounding peaks; it offered ample landing space for the STOL aircraft equipped with wheels and skis, and it appeared to be almost completely free of crevasses except for the lower two or three miles. We could select a site at an appropriate altitude, climbing to it along the usual route up Logan, and supplying it by air with the Helio-courier which was already working on other AINA projects. And our pilot already had more high-mountain flying experience than any one in the country.

Kluane Lake (altitude 2500 feet) was about 80 air miles southeast of Logan; Kluane had a gravel airstrip and a number of buildings, relics for the most part from the construction of the Alaska Highway which ran a hundred yards from the camp. Whitehorse, nearest town of any size, was 150 rough miles to the east, but excellent telephone service, an erratic bus, and twice weekly mail made it much less remote than it had been when Walter Wood (who had established IRRP and was now proposing the altitude study) first visited the area in 1934 by pack train from Whitehorse. It would be easy to set up an adequate base laboratory; the question was could we build and maintain a respectable laboratory in the high, hostile climate on the Logan Plateau?

There were other unanswered questions: Would weather allow us to fly up and back as needed? Would snow on the plateau be safe for landing—not too soft, nor yet storm-piled into compact hard drifts? Could we fly enough missions to supply the large amount of food, fuel, and material needed for a productive study? What studies would be most significant—and at the same time feasible under such field conditions? Above all—could we make the project safe—at least as safe as a climbing expedition?

There had of course been many other studies of man at altitude. On Monte Rosa and the Jungfrau in the Alps, on Pikes Peak, Mount Evans and White Mountain in the Rockies, and at several stations in the Andes. Bert, Mosso, Haldane, Barcroft, Dill and many others had done meticulous work in many areas, ever since the latter part of the nineteenth century. One of the finest and most comprehensive studies was carried on by Pugh during the winter of 1961 when a group of British and American scientists lived in a specially constructed hut at 19,000 feet in the Himalayas. What could we add—or do better? Most work had been done at 14-15,000 feet; we would be several thousand feet higher—and 17,500 feet is considered by some as the highest altitude where man can acclimatize more rapidly than he deteriorates. We would supplement the 1961 study by bringing into play some modern techniques.

That fall day in 1966 we were stimulated by two other considerations. First was the rather startling increase in the number and severity of cases of altitude illness among mountaineers, presumably because of the speed and ease with which more and more people were able to reach high mountainous country. Some rather horrible episodes had already occurred; more were inevitable. What could we learn that might help identify susceptibles (if there are such) or to decrease severity and the risk of death? Could we find out why a person might be ill on one climb and not on another? A similar consideration was the desire of the military for more information about the impact of high altitude on troops. In the 1962 Indo-Chinese border war, large numbers of Indians had been flown hastily from the plains high into the mountains; predictably, large numbers were disabled by altitude illness, whereas the Chinese, acclimatized by months of residence on the high Tibetan plateaux had little altitude difficulty. The Indian physicians had published many thought-provoking papers on the subject, opening new areas for study.

From the beginning there was a second, perhaps major stimulus. In addition to the mountaineers who voluntarily expose themselves to altitude, there are millions of patients with heart or lung disease who are short of oxygen even at sea level. Could we learn from the reactions of healthy man, in the abnormally low oxygen environment of altitude, lessons which would help the sick person in the normal atmosphere of sea level? This might turn out to be the most significant contribution we could make and would more than justify our efforts.

This then was the background against which Walter Wood (climber, geographer, scientist) and Bob Raylor (Director of the Washington office of the Arctic Institute) did the planning; Drs. Charles Bryan and John Cocker would represent the Canadian Forces Institute for Environmental Medicine, Dr. Lowell Becker had been engaged in altitude work in the Andes, Barry Bishop was a geographer mountaineer—one of the few then to have climbed Everest, and I had been actively interested in altitude during Himalayan expeditions and during World War II.

THE EARLY YEARS: Bob Faylor and Dick Ragle did the planning for the first year, enabling 15 doctors, students and technicians, to assemble at Kluane Lake Base in July 1967. The Canadian Forces flew enormous cases of scientific supplies and equipment, to Burwash Landing 35 miles away, and these “Paul Bunyans” were trucked to Kluane, though only a fraction of the equipment would go any higher. The indomitable Barry Bishop led a party of eight from a snow landing at 10,000 feet in the Trench between King Peak and Logan up a long laborious route to the Logan Plateau, reporting by radio that there was ample space for building and no crevasses. Faylor had designed a plywood laboratory; pre-cut to fit the small Helio-courier cabin it was flown up in pieces and christened “Faylor’s Folly” quite unjustly as it turned out. Phil Upton made 25 uneventful trips to the Logan “landing strip” during the eighteen days when weather permitted, and we came to respect weather as a potentially serious obstacle. We learned many lessons that summer, some of which would affect all subsequent operations.

The first episode occurred almost at once. As Bishop’s party climbed in early July, they encountered deep new snow and frequent storms. Two individuals were unable to continue and were left, together with a stong climber in a well-stocked camp at 16,000 feet, planning either to continue after a few days’ rest or to descend to 10,000 feet for evacuation. But the weather deteriorated. One man apparently grew sicker, and his condition as described by radio sounded more and more alarming over the next few days; finally the speaker reported that his tentmate was “gradually losing consciousness.” Their location was inaccessible to fixed wing aircraft, and the only available helicopter was chartered by the Yukon Centennial party. On July 13 th, told that the sick man was critically ill, we rudely commandeered the helicopter, and although the pilot had never landed that high before, in two trips he plucked the party of three from their 16,000-foot camp and brought them to base. We were astonished: the “sick man” was apparently well except for some difficulty in walking which we would later recognize as characteristic of altitude ataxia. By contrast, the one who had called so urgently and persistently for help had pulmonary edema, could scarcely walk and seemed not fully rational—a condition we would come to know as indicative of altitude brain edema. The third climber, from whom we had heard nothing, was fine. Two apparently unaffected individuals had listened while a third broadcast emergency calls for help— for one of them. The correct decisions were made, at the right time, but for the wrong person! This taught us that we must listen not only to the words, but to the tone, the mood, the unspoken vibrations which came over the air from the mountain. One of the insidious effects of altitude is blunting of intellect, judgment and perception. In later years each evening broadcast would be heard on two levels; the spoken word and the unspoken intuitive messages.

There were other lessons too. During one storm a tent was almost completely buried and the three occupants developed shortness of breath and headache before realizing that carbon dioxide from their breathing and carbon monoxide from their stove were building up to danger levels in the sealed tent—another example of intellectual blunting. Such experiences are not uncommon and should have been recognized. No one who was at Kluane that year will forget their return: staggering like drunks because of altitude ataxia, relieved at returning safely from the hostile environment, “intoxicated” by the comforts of Base, one of them, a natural comic, convulsed the entire camp with laughter for most of one night.

At Logan High construction went on. Bishop’s determined crew completed the insulated building, although they were living in marginal conditions: two bedraggled tents with broken zippers, miserable cooking equipment and haphazard meals. But the laboratory was completed, sealed, and marked with a tall pole against winter snow cover. The first stage was accomplished successfully!

We concluded from that first year that we could sustain a laboratory at 17,500 feet on Mount Logan, although storm and poor snow conditions might make landings impossible for several days at a time. We had appreciated how subtle and tricky the effects of altitude might be. Much more careful advance planning of food and equipment would be needed. Though we did not yet know whether we could do good scientific work under such conditions, we thought it possible. In the fall of 1967 the planning group decided to go ahead for a second year.

Accordingly in June 1968 a strong climbing party was landed at 10,000 feet in the Trench and climbed laboriously to Logan High. Once again the Canadian Forces sent equipment and supplies to Kluane, where a smaller scientific party with more modest ambitions assembled in early July. Once again the altitude taught us lessons which would influence our future programs.

For example: one member of the support party climbing up from 10,000 feet became exhausted, and at 18,000 feet was irrational and unable to help himself. He was half carried to a tent near the site of the buried laboratory, but storm delayed his evacuation. Some 30 hours after reaching Logan High he was flown to Whitehorse, recovering remarkably on the way, though still unable to walk on arrival. He was found to have pulmonary edema, but recovered rapidly and within a few days was back at Kluane asking to return to Logan High! A curious, unexplained finding was the presence of small hemorrhages in the retinae of both eyes!

Then one of the scientists with little mountain experience was flown to Logan High after two days at 8500 feet. At Logan High his headache was severe and persistent, though he felt able to climb several hundred feet above camp. He had an irregular heart action from time to time, became short of breath, and felt that he had trouble with his eyes. He was soon brought down and at Kluane he too was found to have unexplained retinal hemorrhages.

Another scientist flew directly to Logan High where he was quite well for five days. He flew back to Kluane for consultation, returning to Logan High 36 hours later where he became mentally confused and short of breath. He was immediately returned to Kluane and found to have pulmonary edema which cleared almost immediately. This seemed to re-enforce the belief that acclimatized persons, re-ascending after a stay at low altitude, might be especially vulnerable.

During the second year ten individuals were flown from Kluane to Logan High, and about 100 blood studies completed with acceptable accuracy. In July, 19 flights were made to Logan High during the 25 flyable days, and almost as many more were made in June before the scientific work began.

The climbing party had twice been struck by altitude sickness, which we had not expected. Living in tents at Logan High for any extended time would be unpleasant and sapping, and larger quarters would be needed; these would have to be well marked to be easily found. Quite likely new buildings would be needed every few years as the old ones slowly sank in the snow! We recognized the possible risks of flying people directly from Kluane to Logan High, even though this would provide cases of altitude illness for study.

But the project was clearly successful. We were confident that the dangers could be minimized and reliable data obtained, and with these reassurances the planning group met in the fall of 1968 to lay long-range plans. Ongoing funds were given by the Fleischmann and the Kresge Foundations, by the Defense Research Board of Canada, and later by the National Institutes of Health. The Canadian Forces increased their support. Word got around, and curious climbers applied to be members of the support team. The scientists came to know each other better, and administration smoothed out.

The scientific protocol planned for the third year included studies of retinal circulation, because following our observations, others too had found hemorrhages, and we began to wonder just how common—and how serious—they might be. A prominent part of the plan for 1969 included photographs and measurement of the retinal circulation.

The general format was much the same: climbers would leave Kluane Lake in late May, fly to Trench, and slowly move up to Logan High. There, hopefully, they would easily find the marker over the cache, although the original laboratory would undoubtedly have sunk too deeply into the snow to be usable. A new kind of building would be used: the Versadome, made of double nylon coverings stretched on an intricate framework of tubular steel. The floor of plywood is on trusses laid on heavy plastic, providing a dead airspace which gives some insulation from the cold. The design has several advantages: it can easily be transported in the Helio-courier, can be erected by a small crew in a few days, and is quite resistant to very strong winds. The double nylon walls make these buildings reasonably warm since space heaters are used. Versadomes and variants have been used each year since.

Scientific studies were designed to examine the changes in the distribution of water and electrolytes which take place during oxygen lack, thus contributing to altitude edema. Measurements of fluid intake and urine output along with daily physical examinations would give estimates of water balance, and perhaps give early warning of altitude sickness. A new scientist with experience in retinal photography would join us, because the unexplained observation of retinal hemorrhages had opened up a new, intriguing and unexplored field. We would still adhere to the plan of flying experimental subjects directly from Kluane Lake to Logan High, expecting them to be ill and thus more suited to the acute studies which we were planning. Scientists too would fly directly from low to high altitude, but in advance of the subjects to allow time for them to adjust. We felt, then though not today, that this would be safe, given proper safeguards. We anticipated that the month of July should enable us to study eight subjects, each of whom would spend five to ten days at Logan High.

We were able to charter a Beaver, a single engine cargo aircraft with a payload of over 1000 pounds to transport supplies and people to 10,000 feet—close to its service ceiling, but only the Helio-courier could supply Logan High—placing heavy responsibility on our pilot. However, in 1968 we had shown that the Jet Ranger helicopter was capable of landing and taking off with a payload of 300 pounds at Logan High; since several of these helicopters were based in Whitehorse, we felt that emergency flights could be made if necessary if our plane were out of service. Weather, though not exactly ideal, seldom caused more than two or three days without flying in succession. Radios were marginally effective: the costly crystal sets which formed the backbone of our communication system frequently gave trouble, maintenance and repair were sloppy, and on several occasions sets were returned by the maker after servicing with the wrong crystal frequency, a faulty crystal oven, or other poor workmanship. Had we been able to afford them, we would have bought more elaborate and more costly radios elsewhere. Military radios on loan from the Canadian Forces, in contrast, operated flawlessly throughout the summer. We had occasional radio blackouts when no transmissions could be sent or received for up to six or eight hours at a time, due to weather.

Things went well in 1969, although one episode might have ended disastrously. One of the subjects, a very fit Canadian Forces officer, flown to Logan High became lethargic on the first day, and within 30 hours of arrival could not be roused. Despite oxygen and other treatment, emergency evacuation was called for and accomplished near midnight 36 hours after he had arrived; at Kluane Lake he recovered in eight hours, and in five or six days was his normal self. We recognized this to be a severe case of brain edema.

During the third program year we also realized more than ever that scientists working at Logan High, flown directly up from Kluane Lake were themselves affected by the very phenomena they were studying, and —more significantly—their radioed observations could not be considered totally reliable. It became clear that an experienced physician had to be at Kluane Lake at all times during the project, listening with the inner ear to spoken and unspoken communications, and making hard decisions whenever these were necessary. The evening radio contact—soon to be known as “the hour of charm” was given to conversational exchanges between Kluane and Logan High, during which observers at Kluane tried to estimate just what the condition of the various people might be. This chit-chat became very helpful, but it was disconcerting to find that people in Whitehorse were also listening avidly to our news!

THE MIDDLE YEARS: By the end of the summer of 1969 HAPS was well established. The logistic patterns were set, reasonably safe and comfortable living was possible, and the flying risks acceptable—providing we had an excellent pilot and aircraft. We accepted the risks taken by flying directly to 17,500 feet, feeling that these could be mitigated by taking acetazolamide in advance, though this did alter our findings. The HAPS group was more than 30 strong including scientists, subjects, support team, pilot and staff. The problem of supplying Logan High was partially resolved when the Canadian Forces agreed to parachute loads at Logan High, thus providing ample oxygen, propane, lumber and food, and excellent real-life practice for the crew. Best of all a respectable amount of scientific information had been accumulated and was being published, though we still had a long way to go before a long-range master plan of research was developed. The group was working as a team: young climbers were eager to join, and we had more applicants than we could use. The scientists were excited about the work, time-consuming and demanding though it was. Canadian Forces support was increasing, and as experience had grown, our confidence in our ability to handle the likely situations had increased.

In 1971 much the same program was followed: ten experimental subjects volunteered from the Canadian Forces and were taken to Logan High in two groups for testing. Five scientists, two technicians, and nine mountaineers made up the party, and despite unusually bad weather (a phrase which seems to have recurred annually!) about three-quarters of the ambitious scientific plan was completed. There were several instructive episodes. One member of the support team, after climbing for one day above the landing at 10,000 feet, became weak and lethargic and unable to continue. Properly conservative, the team leader called for helicopter evacuation; on arrival at Kluane the climber was found in good health. Two weeks later he asked and was permitted to return to 10,000 feet, to be flown to Logan High with the scientists acclimatizing there. Once again he felt unwell, behaved inappropriately, and was returned to Base. Once again he was found well, but as we added together all the pieces it became clear that his “illness” was emotional rather than physical. In retrospect the party agreed that he should not have been taken.

A young member of a mountain expedition attempting the regular route to the summit became ill around 13,000 feet, grew rapidly worse, and with difficulty was brought down to our 10,000-foot camp at Trench, where by good fortune one of the HAPS physicians had just arrived. The climber had severe pulmonary edema, and was treated for 24 hours without improvement before a dramatic night-time helicopter rescue brought him to Base where he recovered completely in a few days. The worst feature of 1971 was the down time of the aircraft. First one thing then another grounded our only plane for 16 of the 31 project days. Had we not been able to charter a helicopter at crucial times, the project might not only have failed but people might have been endangered. We were convinced that two aircraft, and hopefully two pilots, were essential to our effectiveness, and even to safety.

As the 1971 field season ended the scientists agreed that we needed a breathing space to review the data, write papers and to look ahead— planning for a long-term grant application which would give more stability to the program. We also agreed that the risks of flying people directly to Logan High were not justified by the additional data; a staging camp was needed.

Accordingly, no formal HAPS program took place in 1972. Some of the scientists and climbers did go to Kluane under different auspices, looking for an intermediate camp roughly half-way from Kluane to Logan High, through which we could stage scientists and subjects before exposing them to the acute stress of Logan High. An ideal location was found on the Badham-Donjek plateau at 9500 feet and christened Eclipse.

THE LATER YEARS: Both 1973 and 1974 were good years. The Canadian Forces provided air transportation for the party from western Canada to Kluane Lake and most of the supplies and equipment. Fifteen volunteers from the Canadian Forces were briefed about the program and took enthusiastic part. They were taught snow and ice climbing by trained instructors at the intermediate camp—Eclipse—and more elaborate and sophisticated studies were accomplished. The generosity of the Kresge Foundation enabled us to buy a back-up airplane, though it was grounded by one thing or another during most of the project. The most welcome event was award of a five-year grant from the National Institutes of Health, sufficient to provide most of the cash needs of the program. The Canadian donation of flying time, food, supplies and equipment and volunteer subjects together with some funds from Defense Research Board more than matched this dollar award. The program had become truly bi-national, half of the scientists coming from Canadian universities. Though the weather was often “unusually severe,” and the scientific program more ambitious each year, we were able to accomplish most of what we planned. The staging camp at 9500 feet decreased the severity of altitude sickness in subjects and scientists—not an unmixed blessing because we were less able to study the acute illness—but an additional safeguard.

The ninth season—1975 was the most ambitious and least successful. Before the project started, our back-up aircraft was damaged while landing at the intermediate camp, and although it was daringly flown out, structural damage kept it out of commission for the rest of the summer. The faithful original aircraft developed an oil leak, causing a forced landing and ruining an engine; replacement was accomplished but the plane was not fully serviceable for most of the time. The weather was “un-usually unfavorable” and for the first time in nine years none of the experimental subjects reached Logan High. Instead, scientists who had been fretfully acclimatizing for ten days at Eclipse, flew to Logan High and conducted a full schedule of studies on six of the acclimatized support team who three months later would have baseline studies done at sea level. Only about 20% of what we hoped to do was actually accomplished, but some new directions and concepts evolved.

So much for the bare bones chronicle. What has been accomplished?

SCIENTIFIC PUBLICATIONS: Rightly or wrongly, accomplishment in science is often measured in numbers of papers published, although quality and impeccability of data are important. HAPS personnel has published some 30 papers, mostly in refereed journals where peer review is a prerequisite. Other papers have been given to mountaineering journals, various audiences, and to the Armed Forces. It seems to us important to broadcast information about altitude illness, which is occurring more and more frequently as more people have easier access to high altitudes. The observation of retinal hemorrhages in 1968 led the team to a detailed study of retinal circulation, the first time this phenomenon had been described at altitude. (Singh noted a few “vitreous hemorrhages” in the eyes of several of his 2000 cases of acute altitude illness seen during the Indo-Chinese border conflict.)

Other investigators have confirmed the HAPS observations: between 20 and 30% of all persons climbing above 14,000 feet are likely to have retinal hemorrhage, although very few will be aware of them. We believe that they disappear completely leaving no scars and that they are not cause for descent. We also believe that they are increased by exertion. Whether or not these tiny bleeding points in the back of the eye are typical of bleeding areas elsewhere, for example in the brain, no one can say at present; there is no hard evidence that high-altitude climbing causes lasting damage.

The HAPS investigations have confirmed the findings of other groups that some shifts of body water and electrolytes occur at altitude; the evidence suggests that these changes in water distribution are primarily responsible for the signs and symptoms of altitude illness. The HAPS team has begun to study a number of hormones which may be involved in acclimatization, by mediating water and electrolyte distribution. These studies are only beginning, and the data are not always in complete agreement with those of others. New theories of a contributing factor in pulmonary edema are evolving from studies of platelets made by HAPS scientists. Maldistribution of pulmonary ventilation is being studied as are certain promising leads towards prediction of persons more likely than others to be sick at altitude. The condition now known as brain edema has been defined and is accepted as one of various manifestations of altitude illness.

The protective value of acetazolamide taken before ascent has been demonstrated by others; the HAPS group has confirmed these observations, and believes that acetazolamide does give modest protection against acute altitude illness.

Studies of the brain waves, by electroencephalograms taken at rest, during sleep, and after over-breathing and oxygen administration have begun; we have shown that these can be measured at altitude, but whether they will give significant information remains to be seen.

Responsible scientists who are spending other people’s money, whether from federal institutes or private foundations, have an obligation to ask “What have we done?” and “What does it all mean?” HAPS has added appreciably to the fund of knowledge of how man adjusts to altitude. We have observed and publicized previously undescribed aspects of altitude illness, and called attention to the possibility that retinal hemorrhages, reported by others to be present in 30% of newborn infants, may possibly be due to the same mechanism and somehow related to oxygen lack.

As to relevance, we have warned a large number of mountaineers about the risks of rapid ascent, advising them on prevention and management of altitude illness. Whether this campaign will be any more effective than those urging use of seat belts or warning against cigarettes is unclear. Most climbers feel that “it can’t happen to me”—until it does. We are beginning to identify definite similarities between the responses of healthy individuals to high altitude and those of persons with chronic heart or lung disease at sea level. Indeed spin-off projects stimulated by HAPS are now studying chronic pulmonary patients at the modest altitudes to which jet aircraft are pressurized, or to which they would be exposed during a visit to the Rockies. We have little doubt that responses of such chronically hypoxic patients are similar to those of mountain climbers, and may be amenable to the same identifying, predictive, and management techniques.

SAFETY: From the beginning safety has been paramount—safety to the scientists, safety to the climb-up party, and safety to the experimental subjects. Every one of the scientists has undergone—many times—all of the procedures. Subjects are carefully briefed in advance, and sign informed consent papers in compliance with the regulations for National Institutes of Health grants. We take no risks with any subject that we have not many times taken with ourselves. After several seasons we were convinced that flying directly from Kluane Lake to Logan High was unacceptable, and introduced the staging camp. We have seen more cases and more serious cases of altitude illness among other parties on Mount Logan than in our own group.

THE FUTURE: Each of us has somewhat different ideas about future directions. To some, Logan High offers a setting in which to pursue “targets of opportunity”—special research studies which are made tempting by new discoveries in allied fields. To others there is a pressing need to develop a strategic plan for a five-year project, into which new tactics can be fitted each year. The pace with which science is advancing is accelerating with great speed; investigative techniques are constantly being refined; new bits of data and new concepts emerge continually. Some of us feel the need to coordinate, to try to make some order out of knowledge, and especially today perhaps, to show how relevant basic science can be to clinical problems. Some feel that neat packets of information, carefully verified and published for others to learn from, are not enough to justify costly research in today’s world. On Logan High, should we not be developing over-view concepts of altitude illness, acclimatization and basic changes? And should we not be trying to relate these findings to the problems caused by oxygen lack in patients at low altitude?

Logan High is admirably suited for certain types of work—studies which involve active persons engaged in normal daily activities, with ample space to move about, and with living conditions near “normal.” Most workers are satisfied that low pressure chambers, however well equipped, are too artificial to simulate real life, although many sophisticated studies can be best done in such chambers, or while breathing low-oxygen mixtures. But the type of work which interests us can be done in an unfettered setting where, despite cold, and storm, and isolation, more natural activities are possible. Yet we are not interested only in mountaineers. What we are seeking is—and should be—related to the problems of oxygen lack from many different causes. Logan High seems ideal for such studies, high enough, well tested, reasonably safe, reasonably accessible, despite logistic interruptions due to weather.