When talking about altitude, we always think of beautiful landscapes and the purity of the air. Far less often do we think about the difficulties of acclimatization and its direct relationship with atmospheric pressure and resulting altitude sickness.

Less well known than the typical “dizziness” that assails us in certain situations, altitude sickness is just as embarrassing and has a greater impact on the body. There are precautions to take if you decide to stay in a ski resort higher than 2,000 meters or if you are preparing an ascent of a high mountain, so take note!

Altitude and atmospheric pressure

We begin by first describing, what is atmospheric pressure? Also known as barometric pressure after the instrument that Evangelista Torricelli invented in 1643 and used to measure it: the barometer. Atmospheric pressure is the weight of the mass of air on a surface of the earth. If the surface where the weight is exerted is at a different altitude, its atmospheric pressure will be higher or lower. For example, its value at sea level is 760 mm Hg (millimeters of mercury) or 1030 mbar (millibars), using 1 atmosphere as the reference unit with these values. However, the atmospheric pressure at the top of Everest (8,848 meters of altitude), is two thirds lower than at sea level, and is equivalent to 0.33 atmospheres.

The higher we climb a mountain and increase our altitude, the atmospheric pressure decreases as you can see in the following table:

Image: Changes in pressure compared with altitude, I Love Ski.


Oxygen Levels

The amount of oxygen in the air remains the same, but the oxygen concentration decreases with each breath, which is what causes the feeling of a lack of air.

Altitude causes many changes in our body and adaptation is not always evident. As we have just explained, the oxygen concentration does not decrease at altitude since said concentration remains stable during the first 100 km as well as the pressure of all other gases (oxygen, nitrogen, ..).

While at sea level the atmospheric pressure is 100 kPa, at 8848 meters (Everest) the atmospheric pressure will drop to 34 kPa. Therefore, at the top of Everest, the number of molecules in the air (oxygen included) is 34% compared to 100% found at sea level.

Taking that into consideration, we understand that at the top of Everest or in a high-altitude ski resort, we breathe the same concentration of air as on the beach, but the amount of oxygen is less due to the reduction in atmospheric pressure.

Acute mountain sickness

MAM is a French term that means “Acute Mountain Sickness” is very common and can affect anyone. Some factors can contribute to the so-called altitude sickness, such as being overweight, drug and alcohol abuse or fatigue. Its main symptoms are easily recognizable:

  • fatigue
  • insomnia
  • dizziness
  • sickness
  • difficult breathing
  • loss of appetite
  • headaches
Image: acute mountain sickness

AMS, altitude sickness or acute mountain sickness, can be a precursor sign of pulmonary or cerebral edema, you have to be very careful and take it very seriously.

Children and people over 60 are the most affected by altitude sickness. Therefore, it is not advisable to ascend to an excessively high altitude with elderly people or with babies. If you are looking for more information, here are some recommendations for going skiing with a baby.

The effect of altitude will be felt progressively. It is important to climb slowly, especially when your usual residence is at low altitudes or near sea level.

Tips for altitude and avoiding altitude sickness

Here are some tips to avoid altitude sickness if you plan to spend the night or stay in a place that is at a high altitude:

  • Drink plenty of water, don’t wait until you’re thirsty to hydrate.
  • limit the intensity and duration of physical efforts during the first days.
  • Do not make sudden or violent efforts without having passed a period of adaptation to the altitude.
  • try to eat lightly to facilitate the digestive process.
  • avoid stressful and painful situations.
  • Consuming alcohol and smoking is strongly discouraged.

From 2500 meters, you must also make sure to protect your skin and eyes. In fact, it is from this altitude that rays filter the least. Remember that you must always carry with you:

  • sunscreen (protection index 50 minimum)
  • a lip balm
  • polarized glasses
  • a cap or hat with a visor, which also covers the neck

After all these recommendations, you are finally ready to reach the top of your vacations! Enjoy your stay in the snow without fear of altitude sickness.


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