Oxygen is supplied in two ways on the Beijing-Lhasa train . The visible hardware is the oxygen outlets placed under seats , and on the walls in compartments and corridors. Double pronged soft nasal cannulas (not the most efficient delivery , but somewhat more comfortable ) are used with
The invisible part is the extra oxygen that is added directly in to the air of the compartments, to a concentation between 24-25 % .
Oxygen pressure at different elevations at 21 % and 24 % (measured by John B West , 24.1 -25.3 %, see the Revisited .. post)
The only figure that relates directly to how how much oxygen there is in what we inhale is the oxygen (partial ) pressure . One fifth of air is oxygen , this means 21 kilopascal at sea level. At the highest point along the train ride , Tangula pass at 5076 meters the ambient oxygen pressure has been reduced to 11 kPa but inhaling 24 % oxygen(upper curve) instead means that you inhale the same amount of oxygen as on a lower elevation. At Nakchu , 4500 meters , you will actually be marginally better off than in Lhasa.
Oxygen is added from Golmud (2800 meters) and onwards. The oxygen is produced by oxygen generators that separate the nitrogen and bleed the oxygen into the compartments. This is the same technology that has been used for a number of years in for example Chajnantor Observatory , one of the worlds highest civilian workplaces at 5050 meters.
Using the supplementary oxygen lines :
The main advantages of taking the train lies in the time spent between Xining and Golmud (2400-3000-2800) , after that conditions are very close to being at Lhasa´s altitude. Most , but not all , handle coming up to Lhasa´s altitude without any major problems after a intermediate stop but I have for example met one person with early stages of altitude sickness in Tabo , some four hundred meters lower than Lhasa.
Use the oxygen lines if you have any symptoms of hypoxia , i.e. always if you have headaches. Oxygen saturation in the blood will always drop as you lie down, if you had any symtoms during the day you will at least sleep better with oxygen.