High mix : oxygen on the Tibet train

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

these.

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.

Tibet Train , Revisited.

The March issue of High Altitude Medicine & Biology holds an interesting trip report from the Qinghai railway to Lhasa. It brings up the same reservations I held in my earlier post about the onboard oxygen system – and refutes them in some detail.

First of all it leaves speculation aside : John B. West brought along a oxygen meter , which actually showed somewhat better result than what has been said earlier. 24.1 to 25.3 per cent , comparable to what´s being served in recovery wards after routine anesthesia .

My practical reservations about this system could be summed in two simple questions : what happens when you pop off to the restaurant wagon , and the train stops to let off passengers . Opening the doors should mean that the atmosphere more or less instantly equalises with the outside.

The answer seems to be that they don´t open the doors , at least not for the first six hours :

“In fact , we only stopped three times between Golmud and Lhasa , and only at one of these did all the doors open so we could stretch our legs.At the other two apparently only one or two doors were opened for passengers who had arranged to leave or enter the train at that stop. “

Another interesting aspect is what it shows on the changes in modern China , which is illustrated by what is considered acceptable human cost : building the first highways in to Tibet came at a staggering cost in human lives , the Sichuan-Tibet road took 3000 lives , and the road between Xining and Jyekundo meant more than ten dead per kilometer. (See Losang´s article on the Tibet Highways. )

Today the Qinghai railway company claim, with support from the doctors responsible , that not a single worker has died from altitude sickness in what was the highest construction site in the world.

True or not , it is obvious that huge resources were put in place to achieve this goal. Workers had a minimum transport-only time of four days to the highest work sites , oxygen bars were rigged for recuperation … and large field oxygen generators were actually pumping oxygen to the drill face in the highest tunnels, to achieve a few percent increase in air breathed by the tunnel workers.

When all of this failed there was a willingness to pay another kind of price : doctors had and exercised a right to evacuate workers by helicopter , often based principally on a failed balance test.

(West´s editorial is at the moment available  on line , a description of the of the health/safety organisation during the construction can be glimpsed in this article ).

High Tea : Railway to Lhasa

In 2004 the world started to become aware that the the ralway to Lhasa indded was becoming a fact. The near-completion started a chain of reactions : in some Chinese netizens it became an object of national pride (some would say chauvinism) , and among others it was seen as one more nail in the coffin containing Tibetan culture. The Wikipedia  article soon became a  battle ground along predictable lines , starting with What is Tibet , anyway ?

In the media , a lot of attention was centered on the engineering challenges of worlds highest railway , running over 5000 meters high , and the brand new , shiny thing : the worlds first train with a pressure cabin . Everyone – the BBC, Guardian etc went aah .. – so did I .

The one question that would have blown this story to bits was never asked : so what happens when we pop off for a nice cup of tea in the restaurant car that looks so nice ? No air locks ..

The pressure cabin myth has acquired a life on it´s own : you still hear of people boarding the train with that thought , being awakened by the sound of hard drives going clunk! . Bye , bye , iPod.

What eventually materialised was a train with oxygen generators , spiking the atmosphere up to 23-24 percent (according to the latest issue of High Altitude Medicine), and nasal cannulas with low (undefined ) flow of pure oxygen.

Oxygen enrichment was not a new concept , it has been used in high altitude observatories up to 5000+ meters for a number of years , but the train solution is obviously a compromise between comfort/safety and economy : the observatories run by Caltech University use for example 24 % in their observatory at 3800 meters , and 27 % in their highest facility the Cosmic Background Imager at (corrected for difference in air pressure) around 4800 meters , very close to the long high run of the Tibet train.

So how does these numbers work out ? Well , in the context of travelling to Lhasa : surprisingly well . Assuming these figures are correct , you will breathe the same effective oxygen concentration at 4500 meters as in Lhasa – with the added benefit of having access to the supplemental oxygen by nasal cannulas.

This is if everything works as stated – I would expect the whole car dropping down to 21 % more or less immediately every time people get off the train, for one thing .

Not worse than flying in , with a very limited advantage in the time spent before Golmud . Basically the first twenty or so hours on the train is a dead loss , acclimatisation wise , you need to reach something like 2000 meters to start effective acclimatisation. If your motivation to take the train is to be gentle on your system , you will profit a lot more by flying in to Xining , and take train the next day . Golmud would be even better , at 2800 meters , but by all reports it´s harder to arrange your travel onwards from there.

Minimising your time in Beijing , if you have flown in , will also a give a subtle advantage , tying together the time at cabin pressure (2100 meters, at best  ) with the second half of the track.