Today is an acclimatization day in Namche Bazar. Tonight for a second night we will sleep in Namche. Posters at the police check post near Namche exhort trekkers to pay heed to such acclimatization requirements.
Acclimatization helps the body to cope with the reduced availability of oxygen at high altitudes where the air pressure is low. At Namche the air pressure is about 64% of its value at sea level. It will continue to drop as we go up, reaching 50% at the base camp. As the pressure decreases the air becomes thinner and contains fewer molecules than in an identical volume of air at sea level. Therefore, at Namche a normal breath contains only 64% of the number of oxygen molecules in a breath taken at sea level.
The reduced availability of oxygen makes it harder for the blood to absorb oxygen. In response the body takes steps to maintain a life-sustaining supply of oxygen to the tissues. Immediately the breathing becomes deeper and longer, thereby, increasing the rate of air-flow into the lungs. Within minutes of arrival at a high altitude a process is triggered in the body to increase the amount of red blood cells, which absorb oxygen in the lungs and transport it to the tissues. In spite of these steps the oxygen saturation in the blood falls. And within minutes the heart pumps faster to increase the blood flow to the tissues.
Another response is to reduce oxygen consumption in the tissues by lowering the metabolic activity of certain cells and by increasing the efficiency of oxygen usage, as recent research is showing. This may explain the marked differences in how people respond to high altitudes and why people who perform remarkably well at high altitudes may not have any remarkable athletic ability at sea level. Reinhold Messner and Peter Habeler, who first summited Mount Everest without the aid of supplemental oxygen, were found to be physiologically no different from sedentary people at sea level. It is thought that the physiology of such elite high-altitude performers may be better suited to reduce oxygen consumption in certain tissues, a trait useful under oxygen insufficiency, but of no use under oxygen sufficiency.
Yet another response is to reduce the oxygen demand by preferentially supplying it to critical organs such as the brain and the heart while suppressing the supply to non-critical organs such as the digestive system. This suppresses the digestion efficiency, which the affected person feels as nausea, loss of appetite, indigestion, a preference to sweet rather than fatty food, and so on.
Some changes in the body may cause serious problems. A common problem is that fluids start to leak from the capillaries, building up in both the brain and the lungs, for reasons not well understood. This may be how the blood vessels depressurized and equilibrated with the lower ambient pressure, as an engineer I conjecture. The fluid buildup in the brain causes a headache that most travelers to high altitudes experience. An increased fluid build up in brain causes acute mountain sickness (AMS) that around 30% of the trekkers to base camp experience, regardless of their age or physical fitness. The fluid build up reduces when the person stays at the same altitude for a period of time or descends to a lower altitude, relieving AMS. A severe form of fluid buildup in the brain is called high altitude cerebral edema (HACE) and in the lungs, high altitude pulmonary edema (HAPE). Both HACE and HAPE require immediate medical attention and a descend to a lower altitude.
To cope with the reduced availability of oxygen in the air, the body makes a myriad physiological and anatomical changes. If the changes are small the body is able to safely reach a new equilibrium. However, it cannot tolerate too rapid a change, like a bicyclist who maintains balance through myriad, subtle movements in response to the twists and turns and ups and downs of the pavement, but loses balance when forced to make a rapid course correction. Acclimatization is simply slowing down the rate of ascent, to allow the body time to adapt to the lower air pressure. Beyond Namche the rate of ascent must not exceed 1000 ft (300 m) per day and at Dingboche an extra day must be spent to give the body adequate time to adapt.
At Lukla we had crossed into a region called high altitude (8,000-12,000 ft). In Namche we are crossing into a region called very high altitude (12,000 -18,000 ft). In Lukla or Phakding I did not feel the effects of high altitude. In Namche I am beginning to feel the deeper and faster breathing and the faster heart rate. Also my movements have slowed down.
We start at 8:45 am after breakfast. We wear our down jackets as it is cold outside. The painful memory of yesterday’s climb lingers in my mind; I am not looking forward to another day of climb. We walk toward Mount Everest Documentation Center above Namche for our first view of Mount Everest. It is an arduous climb. The effect of the altitude is perceptible. My pace is slow.
We walk to the viewing area at Mount Everest Documentation Center. Mount Everest cooperates. We are able to view its majestic peak, unobstructed by clouds, framed on the left by Mount Nuptse and on the right by Mount Lohtse. From this far, however, its lofty height is not discernible. In contrast, the much lower, but much closer Mount Ama Dablam appears bigger.
Mount Everest was “discovered” from a mountain of data by the brilliant mathematician Radhanath Sikdar, the Chief Computer of the Great Trigonometric Survey of India. He is unlikely to have seen Mount Everest. Even if he had seen the mountain, it is unlikely that he would have recognized its preeminent stature among the mountains of the world. The 39-year old Sikdar’s feat was in computing the height accurately, accounting for the fact that light rays bend as they pass through the air that is thinning with height. When he computed the height as 29,002 feet, he realized that he had found the highest mountain in the world. That was in 1852, and the news was publicly announced two years later. The height is now estimated to be 29,029 feet. The increase in height is mostly from the increased accuracy of the computation, although the mountain is actually growing, but at a much smaller rate. The growth since 1852 is only around 2 feet.
I am fascinated by the clouds blowing off the mountain peaks as though they are taking a puff, a phenomenon noticeable with many Himalayan peaks. I wonder whether sublimation of snow on the peaks in bright sunlight and subsequent condensation of the sublimated vapors could play a role in forming such clouds. Later from the Internet I learn that these clouds, called banner clouds, form because of a different reason: When wind blows across a peak, air on the leeward side rises and the condensing water vapor from it forms the banner cloud.
A statue of Tensing Norgay with Mount Everest in the background is located near the Documentation Center. It depicts his victorious pose on the summit, smiling, holding his ice axe raised high, an ice axe adorned by flags of India, Nepal and UK. We pose to take pictures in front of the statue.
We sit on a low wall that surrounds the viewpoint area. There are two other trekkers sitting there with their guide. The guide has only his left arm. One of the trekkers is the one I had overheard yesterday at the police check post. I will call him Fernando as I do not know his name. Hair is beginning to grow back on Fernando’s large, shaven head. His beard has also begun to grow. He could be in his mid thirties and from California, I think. Fernando asks, “How was the trek yesterday?” “It was hard, very hard” I reply. Fernando agrees,”Yes, I thought so too. I started wondering whether it was a good idea to have come on this trek.” I realize that Fernando was being facetious yesterday when he had suggested trekking all the way to Tengboche.
Ngima points out Kunde hospital and Khumjung School at a distance. They were established by Sir Edmund Hillary to serve the Sherpa community. I can vaguely see the buildings at a distance. Ngima points out a flat trail to Tengboche at a distance; I long for that flat trail.
Ngima takes us to a trail that goes around Namche Bazar, high above. From the gate of the Namche it is quite a climb to get to the trail surrounding it. Namche is built on steps made on the side of a mountain that has soil and vegetation. Right across from Namche are mountains that are rocky and barren. It is surrounded by towering mountains, many of them snow peaked. A stream flows through the center of the village, where we find women washing clothes.
I wonder whether Namche Bazar means Salt Market. I am not sure whether I read that somewhere. The word namche sounds similar to namak or salt in Hindi. In olden days Tibetans coming from the north through Nangpa La or Nangpa pass (5,806 m or 19,050 ft) used to bring salt and trade it for grains and other goods brought from the south. It must have been an important trading center as salt was a scarce commodity in the past, its preciousness having a lasting effect on our languages. The word “salt” is the root of the word “salary,” still precious for most people. The word appears in a typical statement made by servants in old Bollywood movies, to show that they value their loyalty to their masters: Sardar maine aapka namak khaya hai (Sir, I have eaten your salt). The availability of sea salt from India diminished the salt trade from Tibet. Later Tibetans started bringing textiles, blankets and low-cost goods from China for trade. Even that has ended now as China closed Nangpa La presumably to stop Tibetans from fleeing Tibet.
We see yaks for the first time. A Sherpa and his wife are tending to a herd of seven. A couple of them look different because they are without horns. Ngima tells us that they are also yaks, not female naks. The yaks can be distinguished from dzos by the large amount of hair hanging by the sides of their body.
We come to Namche helipad. It is simply a flat area, paved with broken stones. Yesterday I was wondering why Dorjee had to come for the rescue, if the patient was going to be rescued by a helicopter anyway. Now I understand: Taking a person from Namche to the helipad high above wont be an easy task.
We descend into Namche and pass through Namche market with its shops catering to trekkers’ every need. Also there are shops stocked with usual touristy trinkets.
We get back to hotel and sit down for lunch. We select the Dal-Bhat set menu. It comes with rice, lentils, one or two vegetables and papad. Everything is freshly made with locally available vegetables. That makes them taste good.
In the dining room there is a framed letter of appreciation from Nepal’s Prime Minister Madhav Kumar Nepal to the owner Lama Kanji Sherpa for his help in organizing a historic cabinet meeting at Kala Patthar (18,514′) in December 2009. I wonder how many of the ministers, who are likely to be old, made it to Kala Patthar for the cabinet meeting. “Just a show,” Ngima explains. “The ministers went by a helicopter and were wearing oxygen masks.” Kanji says that the meeting lasted only one hour.
We take a hot shower at a cost of $10. The bathroom is outside the hotel, and it is cold. There is only one valve to turn. Hand written instructions on the heater forbids you from changing the temperature setting. When I turn on the tap I hear a gas heater violently turning on. Water and steam gush from the shower head. The water is very hot, but soon I get used to the temperature. When I turn off the shower, steam comes from my body, making me look as though I am fuming.
It starts to rain. Thick mist obscures the view of the mountains surrounding Namche. Ngima tells us that in the mountains the mornings are usually clear, but the afternoons could bring rain or snow and winds. Ngima suspects it could be snowing in Tengboche. Ngima seems to be concerned about the added challenge tomorrow because of the snow.
Bärtsch, P. and Gibbs, J.S.R., “Effect of Altitude on the Heart and the Lungs”, 2007, DOI: 10.1161/CIRCULATIONAHA.106.650796.
Martin, D., and Windsor, J. “From mountain to bedside: understanding the clinical relevance of human acclimatisation to high-altitude hypoxia,” Postgrad Med J 2008;84:622–627. doi:10.1136/pgmj.2008.068296.
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