Did you grow up in the countryside? Then you are less likely to have an allergy.

Living in both a city and a village has its advantages. This applies not only to the comfort and amenities available, but also to your health. Did you grow up surrounded by vast meadows or spend a lot of time outdoors in nature as a child? Then you might be less likely to suffer from bothersome allergies later in life.

Several studies show that people who grow up in a natural environment actually develop allergies less often. How does that work? NTR Wetenschap discusses this issue with immunologist Hermelijn Smits. "Allergies are increasing significantly in young children, but this isn't the case everywhere. In vast rural areas, and especially among children growing up on farms, there's no increase in allergies or asthma at all."

This phenomenon caught the attention of researchers: this seemed to be the place where something unusual was happening, where a protective effect on the immune system might be present. "Something's happening here, we need to know more about this. What's happening here that could potentially have a protective effect?" says the immunologist.

The idea is that the solution is literally in the air. "Research shows that children who spend half an hour a day in a farm's cowsheds between the ages of one and nine are particularly protected against this," Smits emphasizes. Exposure to the pollutants in the farm's air appears to train and strengthen the immune system, resulting in a lower risk of allergies.

Growing up on a farm, in particular, appears to make you immune to many different ailments, including asthma. Smits: "On family farms where the farmer lives with his family and everyone contributes, this often happens naturally."

The air in such a barn is good for everyone's immune system, but especially for children's. "A child is essentially placed in a rocking chair by the pond while the parents shake hay and tend to the animals. This way, the child is exposed to all kinds of microbes and substances in the air, naturally exposing and strengthening the immune system," says Smits.

But how does that work exactly? What substances contribute to such a strong immune system? This is also known as "farm dust." Farm dust may not sound inviting, and that's partly true: it's not fresh air either. It's full of plant debris, dead mold, and bacteria. As soon as you step into the barn, you breathe it all in. At first glance, this seems anything but healthy, and indeed, people who live near livestock farms have a slightly higher incidence of pneumonia and lower lung function, according to the Dutch Lung Foundation .

However, the Dutch Lung Foundation also sees an unexpected benefit from dust for children. Those who grow up on a farm or live near animals are less likely to develop asthma or nasal allergies. Farm dust appears to naturally train these children's immune systems.

Scientists are now curious to see if they can mimic that protective effect. The goal: to develop a treatment that can also help city children prevent asthma and allergies, without them having to play among cows.

Immunologist Smits is also investigating how this effect can be mimicked: "It could be done with a pill. You could also consider something you spray in the nose. Such a pill or nasal spray could be given to children, especially at a young age, to prevent allergies later in life. But developing that will take some time."

Smits explains why that stable air is especially crucial for children: "Young children still have to fully develop their immune systems. The first thousand days are the most crucial. If you come into contact with various microorganisms during that period, the immune system learns to build up a threshold: it remains calm under low-level stimuli, and only really kicks into action under higher-level stimuli."

In the lab, scientists discovered that farm dust provides the lungs with a kind of extra protective layer. The lining becomes stronger and denser, making it harder for allergens to enter. In addition, respiratory infections appear to be less severe. This is important, because young children who develop severe lung infections have a higher risk of developing asthma later in life.

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