A mask to help acclimatize

In April 2015, a team of French doctors have just tested a face mask on over thirty voluntary mountaineers and hikers passing through Manaslu (Nepal) base camp. This new lightweight device will likely improve the ability to acclimatize at altitude or to treat the symptoms for acute mountain sickness (AMS, or altitude sickness).


  • Project partner: Association Exalt
  • Country: Nepal, Asia
  • Project type: Scientific research
  • Budget: €8,000 in 2015

Doctors from the Université Grenoble Alpes’ Physio Pathology Hypoxia lab and France’s national institute for health and medical research (INSERM) have developed a face mask that provides the ability to artificially increase pressure in the lungs by restricting exhalation. This process, already experimented with in the laboratory in 2011, and then at the Vallot hut (4362m) in 2012, demonstrates the potential for being able to make the slow acclimatizing process at high altitude much easier as well as to reduce the symptoms for someone with acute mountain sickness.


In spring 2015, tests conducted at the Manaslu base camp, located at approximately 5000 meters elevation, confirmed the merit in using an expiratory pressure face mask. The thirty volunteers improved their oxygenation as if they were located 1500 meters lower. One of the members of this experiment, who had a serious case of AMS, was treated with both the face mask and drugs. Thanks to this device, he spent the night at base camp in stable condition before descending to a lower altitude the next day.

There are currently only two non-pharmaceutical solutions to treating problems associated with acclimatizing at high altitude or for a case of AMS: immediately descending to a lower altitude or placing the person in a hyperbaric chamber (aka “Gamow bag”). In the field, it is not always easy to descend to a lower altitude with someone who has AMS due to either their deteriorated physical state or poor weather conditions. In most cases, a hyperbaric chamber is not at all practical: other than requiring specific training for use, no one ever carries one in the bottom of their pack due to its bulk, weight (5kg / 11lbs.), and price (3800 €).

The masks tested on Manaslu this spring have raised real hope among the community of mountain physicians. Lightweight, easy to pack, and simple to use, they could soon find their rightful place in the first aid kits of everyone who ventures to high altitude. Researchers are now working on a prototype for the general public that should hopefully be available within the next two years.





An increase in elevation is accompanied by a decrease in the amount of available oxygen in the air.
At the top of Mt. Blanc (4810m / 15,881 ft.), the air you breathe contains half the oxygen available than when at sea level. On the summit of Mt. Everest, human beings function at only 20% capacity.
When confronted with a lack of oxygen, the human body attempts to adapt by raising the breathing and heart rate, as well as by increasing the number of red blood cells. This slow process is called acclimatization. One week is required to completely acclimatize at 4000 meters elevation. Ascending too quickly often means headaches, nausea, difficulty sleeping, and even sleep apnea. Poorly acclimatizing can lead to acute mountain sickness (AMS), and even to pulmonary and cerebral edemas in the worst case scenarios.

Uploaded in November 2015



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