There are two oxygen supply systems on Tibet trains. The first one is to mix with the air in air-conditioner system, to make the oxygen content in each coach reach 23%. The other system can let passengers uptake oxygen directly through the independent port - just like we commonly see on airplane. Passengers will not feel hypoxia on Tibet trains due to enclosed coaches and oxygen supply in the coaches.
In hard sleeper coaches, soft sleeper coaches, hard seat coaches, there is oxygen uptake equipment at each berth or seat. The oxygen uptake equipment is on the wall of head of berth or under the seat where you can get easily. Passengers can directly raise the cover and use finger to press the hole, the oxygen will come out. The oxygen content is 30 % to 50 %. Passengers can directly uptake oxygen when feel uncomfortable. Before Golmud Station, every passengers of Tibet trains will get a oxygen mask.
In order to increase the oxygen content in Tibet trains, there is a oxygen making machine in front of the crew lounge in every coach. The machine determines the altitude of the train through satellite positioning software. When the train reach 3000 meters above the sea level, the machine will send out oxygen automatically and mix with the air sent out by air conditioner, and send into the coaches. Due to the special oxygen supply system of Tibet trains, the trains are enclosed and non-smoking in the whole journey.
In consideration to the passengers in hard seat coaches may appear high altitude sickness more easily for tiredness, the whole train used "airtightness" design and the door used enclosed structure. The pressure in Tibet trains can be automatically adjusted with the change of altitude which greatly alleviate high altitude sickness.