The mountains, especially above 1500 meters, are often presented as a "dust mite-free" zone, ideal for people with dust mite allergies. This reputation is based on some truth: the air is colder and drier, which hinders the survival of dust mites. However, some recent studies show that allergens can still persist in some homes, even at high altitudes. Here's why.
Before addressing the issue of allergenic dust mites at high altitudes, it's important to remember that not all dust mites are allergenic. In natural environments, up to 1800 meters in altitude, harmless species of dust mites, such as Oribates and Prostigmata. These mites live in the soil, on dead leaves, or in moss, and feed on microorganisms or decaying organic matter. They do not infest homes, do not feed on human skin flakes, and are not implicated in respiratory allergies.
While mites naturally present at altitude, such as Oribates or certain Prostigmata, are harmless to humans, the situation changes when moving from the external environment to the internal environment.
Indeed, an Austrian study (Grafetstätter et al., 2016)* showed that allergenic dust mite proteins, such as Der p1 and Der f1, were detected in dust from homes located above 1500 meters in altitude. In some cases, researchers even identified live dust mites belonging to species known for their allergenic potential, notably Dermatophagoides pteronyssinus.
This does not mean that all dust mites found indoors are allergenic, but rather that species known to trigger allergic reactions can survive at high altitudes.
Because inside homes, conditions are very different from those of the outside environment.
Heating, reinforced insulation, poor ventilation and the presence of many textiles (carpets, curtains, mattresses, etc.) can recreate inside the home a climate perfectly suited to allergenic dust mites : a stable temperature around 22°C and sufficient humidity for their survival, or even their development.
Dust mites do not come from the outside environment, but are unknowingly introduced via belongings brought from the plains : unprotected bedding, unwashed linen or infested textiles are enough to transport them into mountain accommodations.
If indoor conditions are favorable, these mites can then survive and multiply, despite the altitude.
Climate change also plays a role in this trend. At higher altitudes, winters are now less dry and average temperatures are higher. Even in newer homes, humidity can stagnate indoors: high insulation, inefficient or poorly maintained ventilation, and long periods without airing between stays create a climate conducive to dust mites. All these factors maintain an environment favorable to allergenic dust mites, even at altitudes above 1,500 meters.
Altitude alone is therefore not sufficient to guarantee the absence of allergy risk.
It's sometimes said that dust mites can't survive in the mountains due to a lack of oxygen. But in reality, their metabolism is very slow and their oxygen requirements are extremely low. So it's not the atmospheric conditions themselves that prevent them from living at altitude. What really bothers allergenic dust mites is the cold, excessively dry air, and especially the absence of human skin flakes , which they feed on. As soon as an indoor environment recreates these conditions, their presence becomes possible again.
The mountains, especially above 1500 meters, remain a favorable environment for people allergic to dust mites, provided that vigilance is not relaxed inside the accommodations.
Because while allergenic dust mites don't migrate to high altitudes on their own, it's we who transport them there. And in some cases, indoor conditions can allow them to survive, or even thrive, despite the cold and dryness outside.
This is precisely what the study by Grafetstätter et al. (2016) : it is not altitude or outdoor humidity that determines the level of exposure to allergens, but rather the way the home is designed, equipped, and ventilated. Unprotected bedding, numerous textiles, poor ventilation, etc., are all factors that can, on their own, promote the presence of allergenic dust mites, even at high altitudes.
The good news is that it's entirely possible to enjoy the benefits of altitude while limiting allergy exposure. A few simple precautions can make all the difference:
These covers, manufactured under ISO 13485:2016 certifications (medical device standard), constitute allergens dust mite, even at high altitudes.
* Grafetstätter C. et al. (2016) – No Concentration Decrease of House Dust Mite Allergens With Rising Altitude in Alpine Regions