The first ascent of Mount Everest, 1953: the solution of the problem of the 'last thousand feet'

Journal of Wilderness Medicine 4,312-318 (1993) REVIEW The first ascent of Mount Everest, 1953: the solution of the problem of the 'last thousand feet' MICHAEL WARD Worshipful Society ofapothecaries oflondon, Black Srars Lane, London EC4V 6E1, UK Pugh's pioneering work at high altitude on Cho Oyu in 1952 dictated the framework for the first ascent of Everest in 1953. He demonstrated that a flow rate of 4 litres of oxygen per minute in the open circuit sets was necessary to provide a boost to performance sufficient to climb Everest from a high camp, at 8600 m, with a safe return to the South Col (8000 m) in one day. Sleeping oxygen mitigated high altitude deterioration, as did Pugh's insistence on a very high fluid intake to combat dehydration. Together with adequate protection from the cold, which was less severe than predicted, these strategies resulted in all climbers who went above 8000 m being in good physical and mental condition. Key words: Everest, high altitude, supplementary oxygen Introduction After finding a feasible route.to the summit of Everest on the first reconnaissance in 1921 from Tibet, all attempts in the 1920s and 1930s failed within a thousand feet of the summit. Each expedition was well organized and led, and the climbers were very capable of overcoming all technical mountaineering difficulties, yet the altitude barrier frustrated success. Between 1921 and 1938, about 25 people had reached an altitude of 8230 m and above, eight of them climbing to 8600 m, both with and without supplementary oxygen. Pre-war expeditions were restricted to the Tibetan approach, as the southern Nepalese side was forbidden to all foreigners. This changed in 1950 when Tibet closed her borders, but at the same time, as the result of a bloodless revolution, Nepal opened her country to foreigners. This provided an opportunity to explore the Nepalese side of Everest and to find a new route to the summit. If this was successful the solution of the problem of the 'last thousand feet' would have to be solved. The first visit of westerners to the Nepalese side of Everest was in the autumn of 1950. The party included Dr C.S. Houston and the British Himalayan explorer, H.W. Tilman. They were pessimistic about a route to the summit. This view was not shared by a group in the UK consisting of W.H. Murray, T.D. Bourdillon and M.P. Ward who searched the archives of The Royal Geographical Society and eventually found photographs and a map of each step of a possible route [1,2]. Despite this information, the Everest Committee of the Alpine Club and Royal Geographical Society, which had been responsible for all expeditions to the mountain since 1921, were sceptical about their chances of reaching the summit. Ward, at that time an officer in the Royal Army Medical Corps, was put in touch with Dr Griffith Pugh of the newly formed Division of Human 0953-9859 1993 Chapman & Hall

The first ascent ofmount Everest, 1953 313 Physiology of the Medical Research Council in London. Pugh's background was ideal in that he had investigated problems relating to cold, exercise and moderate altitude at the Mountain Warfare Training Center at The Cedars of Lebanon in the Middle East during World War II. Ward saw Pugh at his laboratory at Hampstead in the summer of 1951 and discussed the physiological problems caused by climbing the last thousand feet of Everest. By reviewing accounts of the early climbers on Everest and Kangchenjunga, and the findings of Operation Everest I when two volunteers ascended over 32 days to the 'Summit of Everest' (8848 m) in a decompression chamber at Pensacola Naval Air Station, Florida [3,4] Pugh came to the conclusion that in spite of all the prior failures a successful attempt should now be possible, provided adequate supplementary oxygen was used. In the meantime, Shipton, one of the world's most experienced Himalayan explorers who had just returned from a diplomatic appointment at Kunming in south west China, was asked to lead the reconnaissance of Everest in autumn (fall) 1951. This reconnaissance confirmed the presence of what looked to be a feasible route to the summit. On our return to the UK in December 1951 we learnt that the Swiss had obtained permission to attempt Everest in the spring of 1952. As a consequence, a British party elected to go to Cho Oyu (8200 m) 25 miles west of Everest. Cho Oyu 1952 [5) The purpose of this expedition was twofold. To provide a nidus of climbers with highaltitude experience to tackle Everest in the spring of 1953, and for Pugh to obtain data for the design of a satisfactory oxygen apparatus for such an attempt. In addition, he planned to follow the changes occurring during acclimatization and deterioration while living at high altitude. Although the 'technical' mountaineering difficulties on Everest did not appear insuperable, no mountaineer using supplementary oxygen had been given a boost to performance sufficient to enable him to ascend to the summit from a high camp and descend in a day. Nor was there, at the time, any evidence that any mountaineers' physical performance was good enough for him to climb Everest without supplementary oxygen, despite the physiologic observation in the sedentary setting of the high altitude chamber of Operation Everest I in 1946. The use ofsupplementary oxygen Supplementary oxygen had been taken on every Everest expedition except the reconnaissance parties of 1921 and 1951. However, the equipment used by pre-war expeditions was primitive and many mountaineers were unconvinced of its usefulness. Oxygen was used by Finch in 1922, Odell, Mallory and Irvine in 1924, and Lloyd and Warren in 1938. Each used open circuit apparatus weighing in the region of 28 lbs (13 kg). Finch and Lloyd used a flow rate of 2 litres per minute. Their claims for increased speed and reduction in fatigue were disputed by their doubting companions who relied on acclimatization alone. In 1924 Odell tried using oxygen at only one litre per minute and concluded that he climbed better without it. The site of Pugh's physiology camp was on a level area just below the Menlung La (5400 m), a pass crossed by Shipton and Ward the previous year. Its position was glorious, dominated. as it was by the elegant pink granite peak, Menlung Tse, crowned

314 Ward with an icing of snow. A prepared exercise track was made in the snow with a measured height difference. As this froze overnight and became soft at midday all trials were carried out between 10.00 am and 11.00 am. A series of exercise experiments climbing the prepared track were carried out using different flow rates of oxygen, with a stop watch for timing. I Pugh showed that, at an altitude of 5400 m, a flow rate of 4 litres per minute was necessary to compensate for the weight of the set and provide a boost to climbing rate. Effectively, pre-war expeditions using 2 litres per minute were only climbing as fast and as high as their colleagues relying on acclimatization alone, because a 2-litre flow rate was insufficient and compensated for the weight of the set only, but did not provide a boost to performance. However, it has to be mentioned that at higher altitudes lower flow rates will eventually suffice to offset weight. Pugh also demonstrated, as had Finch before him in 1922, that sleeping with oxygen at one litre per minute combated fatigue, and by producing a feeling of warmth enabled him to sleep well. The use of 100% oxygen produced a faster climbing rate than 4 litres per minute, and as a result the closed circuit set was developed by the Bourdillons, father and son. Fluid balance Prior to this time no data was available regarding fluid loss from the lungs leading to dehydration. Observations by Pugh, confirmed the assumption that at altitude, lung air is at body temperature and fully saturated. As the partial pressure of water in the lungs is constant at 47 mm Hg- t at a body temperature of 37 C, the water content of expired air is independent of altitude, and water loss from the.lungs is virtually a function of ventilation (BTPS) and therefore related to physical activity (Table 1). At high altitude the water loss from the lungs may exceed as much as 1.5 litres per day or more, depending on the level of exercise. Despite a fluid intake of 2 litres on both the 28 and 29 of May, 1953, Hillary showed clinical evidence of dehydration for some days after his first ascent of Everest. Food, climate, insulation A food intake of 3000 kcal per day with a high carbohydrate content was considered by Pugh to be essential to maintain weight. Other investigations into the insulating value of clothing, tents, boots, gloves and the Table 1. Water loss via the lungs in litres per 24 h, at temperatures ranging between 0 C and -20 C, calculated for various altitudes and rates of metabolism Barometric Altitude measure Metabolism (kcal) (feet) (mm kg) 2000 3000 4000 SL 760 0.35 0.52 0.69 20000 370 0.76 1.15 1.53 24000 310 0.94 1.41 1.88 28000 276 1.08 1.62 2.15

The first ascent ofmount Everest, 1953 315 use of stoves, completed a series of investigations that established many of the foundations for the ascent of Everest in 1953. Comparison with Swiss on Everest, 1952 Finally, Pugh was able to compare the Swiss performance on Everest in the spring of 1952 with that of the British on Cho Oyu at the same time. The Swiss performed much better in that they were fitter, had less intercurrent infection, were better acclimatized and ascended more rapidly to higher altitudes than the British party. However, resistance to breathing of their oxygen apparatus coulq not accommodate the high ventilation rates of Lambert and Tenzing above 8000 m. Consequently the sets could only be used at rest, with of course no boost to climbing rate. As a result, Lambert and Tenzing failed to reach the summit. Everest 1953 (6) On return to the UK from Cho Oyu in the early summer of 1952, the Everest Committee accepted all Pugh's recommendations for the 1953 expedition. Supplementary oxygen On pre-war expeditions, those climbers who had used supplementary oxygen, even at a relatively low flow rate, considered that the higher the altitude the greater the boost to performance; Pugh's work on the Menlung La confirmed this. The increased flow rate of oxygen considered essential by him would require more oxygen to be carried at a greater pressure in cylinders of a greater strength, and made from lighter materials developed during World War II. The open circuit sets with three cylinders of oxygen weighed 20 kg. At a flow rate of 4 litres per minute at 8848 m the climber would be breathing the same concentration of oxygen as if he were at about 6000 m, an altitude at which it is possible to climb to a high standard. Pugh's observation that the use of 100% oxygen gave a greater boost, resulted in the development of the closed circuit set. This set, which incorporated soda lime cannisters to absorb carbon dioxide, weighed over 23 kg. It had the added advantage of conserving heat and water (lost from the lungs at altitude), but being more complicated, it was less reliable. Using these sets Evans and Bourdillon made the first ascent of the south summit (8650 m), climbing at twice the rate of those using the open circuit, but one set malfunctioned on the south summit and both very sensibly turned back. The risk of set failure would have meant sudden exposure to extreme altitude (from 'sea level') with the possibility of coma and death. The use of sleeping oxygen at one litre per min above 8000 m was also beneficial [7]. Food, climate, insulation Food intake up to 6000 m averaged 3500 kcal, whilst above this altitude it fell to 2600 kcal with a high proportion of carbohydrate. The average weight loss while above 6000 m was 2 kg. Good protective clothing was provided to combat the severe cold and wind which normally occur on Everest. Between 5400 m and 6000 m the minimum night temperature varied from _13 C to -20 C. By contrast, sun temperatures of 69 C (156 F) were measured with a black

316 Ward bulb radiation thermometer. In the western cwm, temperatures inside a tent fell from 30 0 C to 0 0 C within 2-3 min as the sun came off the tent at dusk, whilst at sunrise the temperature rose from 0 0 C to 25 0 C within 1.5 h. Climbers suffered from the heat in the western cwm. Minimum night temperatures were not recorded on the South Col in the spring of 1953, but on the night of 28/29 May, Hillary recorded a temperature of -27 0 C at 0.300 hours at 8600 m outside his tent. This temperature was higher than expected as extrapolation from data on Cho Oyu in 1952 suggested a temperature on the South Col, 8000 m, of -25 0 C to -35 0 C and at 8600 m -29 0 C to -36 0 C. A very high wind at this altitude, such as that encountered by the Swiss party in the autumn of 1952, would prohibit climbing. Double sleeping bags with a total weight of 3.5 kg of down were used, and these would have provided sufficient protection at temperatures as low as -40 0 C. However, to save weight only single bags were taken to the South Col and all felt the cold. If predicted temperatures of -35 0 C had been encountered instead of about -25 0 C, the situation might have been dangerous. The main insulating garments were a quilted down jacket and trousers with an outer windproof smock and trousers, chosen after extensive wind-tunnel tests at the Institute of Aviation Medicine. Special boots, based on a double. vapour barrier principal, were provided for use over 6000 m, but were not successful. Tenzing wore the Swiss boots he used in 1952 and they were preferable in every way. Much attention was paid to weight, as metabolic studies had shown that 0.5 kg on the feet was equivalent to 2 kg on the back. Tents of many different types were taken - the modified Meade-an A-frame tent with a single skin and sewn-in ground sheet was most popular. First Ascent on 29 May, 1953 A most critical factor in the first ascent of Everest was the use of adequate supplementary oxygen at 4 litres per minute. The relatively smooth and eventless ascent by Hillary and Tenzing contrasts starkly with the tortured account of Norton in 1924, climbing without oxygen at 8600 m. "Our pace was wretched. My ambition was to do twenty consecutive paces uphill without a pause to rest and pant elbow on bent knee: yet I never remember achieving it - thirteen was nearer the mark." "Every five to ten minutes we had to sit down for a minute or two, we must have looked a sorry couple". [8] The key effect of adequate supplementary oxygen was that it enabled climbers to ascend more or less continuously without having to stop every few minutes, thus increasing overall rate of climbing. The last thousand feet was a venture into the unknown. Hillary and Tenzing were able to remove their masks on the summit for ten minutes before becoming a little muzzy. All their movements and actions were quite sensible and on their return to camp four in the western cwm the following day, they were able to give a clear, detailed and accurate account to Ward. The following account is from his diary for these days. 28 May, 1953 Hillary and Tenzing left the South Col at about 10.00 am using 4 litres per minute on

The first ascent of Mount Everest, 1953 317 their open circuit sets. Hillary was carrying 49 lbs and Tenzing 44 lbs gross. At 27300 ft, where a dump of gear had been left by the support party, Hillary added a tent to his load, which now weighed 63 lbs, but he increased his flow rate of oxygen to 5 litres per minute, for about 30 min. He noticed an appreciable difference, he felt more energetic and everything went much more easily, like changing gear. At 2.30 pm they reached a suitable camp site at 27800 ft. Both Hillary and Tenzing removed their oxygen sets for 2.5 hours - from 2.30 pm to 5.00 pm, and worked hard making a camp site, clearing the ground of rocks, snow and ice and levelling a platform. They had to sit and rest every now and again, but pitched their tent without trouble. For an evening meal they brewed soup leavened with sugar. Also they ate a tin of apricots, some jam, biscuits and sardines. Hillary sat up all night and did not feel particularly cold. They had 4 h on sleeping oxygen at one litre per minute in 'doses' of one hour at a time. When using sleeping oxygen they slept lightly. The temperature outside the tent fell to -27 0 C. 29 May, 1953 They left at 6.30 am using oxygen at 3 litres per minute, with loads of 30 lbs. They got to the south summit (28700 m) at 9.00 am. On the south summit they dumped one bottle of oxygen and so carried about 20 lbs from the south summit to the main summit. This took about 2.5 h with Hillary leading all the way. Step cutting and kicking steps was not particularly hard work. At the Hillary step, melting snow had left a gap between the rock and snow and ice, and this was climbed by back and knee - the most energetic piece of climbing that they did that day. Tenzing felt tired, but Hillary felt that he was going well. More step-cutting led the party to the summit at 11.30 am, where they remained for 15 min. Hillary removed his mask and took photographs for 10 min, he felt slightly weak, but could move carefully. He was not confused mentally. He passed urine and ate a piece of Kendal mint cake. Tenzing removed his oxygen for about 5 min. They left the summit at 11.45 am. They took about an hour to get to the south summit and then went quickly down to the camp at 27800 ft. The snow was dangerous but no slipping occurred. They were rather tired but made good progress. When they reached the camp (27800 ft) at 2.00 pm, they made a quick brew of lemon juice. They left the camp at 3.00 pm, dumping the empty oxygen bottles and taking a partially filled one. Table 2. Climbing rates of Everest expeditions 1922-53 Altitude difference Gross load Rate ofclimb Party (ft) (lb) (ft per h) Oxygen apparatus 1922 25000-27000 320 NONE 25500-27200 40 about 400 2.41 per min 1924 25300-26800 333 NONE 1952 25800-27200? 233 O 2 at rest only 1953 25800-27 200 40 622 4 I per min open circuit 25 800-27 200 40 494 4 I per min open circuit 25800-27200 52 933 closed circuit 1953 27900-29000 17 210 3 I per min open circuit

318 Ward They descended on 2 litres of oxygen per minute,. carrying about 30 lbs down the ridge to the couloir. They felt tired but took it steady. At the couloir, steps had to be kicked down to South Col. The oxygen lasted until just above the South Col. Little difference was noted when the oxygen stopped, except on going up hill on the Col. On the South Col, Hillary and Tenzing arrived much fresher than the other parties going above the South Col. Hillary and Tenzing stuck rigidly to Pugh's principles of 4 litres of oxygen on ascent, 2 litres on descent and 1 litre when sleeping, and in addition they each had about 2 litres of fluid on the 28 and 29 May. Despite this, Hillary was clinically dehydrated on returning to the Western Cwm. The key to our success in 1953 was the provision of adequate supplementary oxygen that increased climbing rate (Table 2). If such a boost had been available to Everest expeditions of the 1920s and 1930s Everest would probably have been climbed then. On this expedition there were no accidents, and only two mild cases of frostbite. The mental and physical mobility of the party enabled us to react decisively, and make correct decisions because our overall mental and physical condition was so good. This was a point commented on when we returned home. References 1. Ward, M.P. The exploration of the Nepalese side of Everest. Alpine Journal 1992/93; 97, 213-21. 2. Ward, M.P. and Clark, P.K. Everest 1951: cartographic and photographic evidence of a new route from Nepal. Geographical Journal 1992; 158,47-56. 3. Houston, C.S. and Riley, R.L. Respiratory and circulatory changes during acclimatisation to high altitude. American Journal ofphysiology 1947; 149, 565-88. 4. Houston, C.S., Cymerman, A. and Sutton, l.r. Operation Everest II. 1985. US Army Research Institute of Environmental Medicine: Natick, MA, USA, 1991. 5. Pugh, L.G.C.E., Report on Cho Oyu Expedition 1952. Medical Research Council, London 1952. 6. Pugh, L.G.C.E. Scientific aspects of the expedition to Mount Everest, 1953. Geographical Journal 1954; 120, 183-92. 7. Bourdillon, T.D. Oxygen apparatus on the mountain (Everest 1953). Alpine Journal 1953/54; 59,247-63. 8. Norton, E.F. Norton and Somervells attempt. In The Fight for Everest 1924, London: Arnold, 1925.