Children who grow up on a pig or dairy cattle farm have a natural vaccination against the form of work-related asthma from which farmers frequently suffer. This has now been proved for the first time ever by researchers from Aarhus University.

The study, which has been published in the Journal of Allergy and Clinical Immunology, demonstrates that the risk of developing the non-allergic form of asthma is reduced by almost fifty per cent if you are exposed to the kind of environment found on pig and dairy cattle farms when you are a child. On the other hand, the risk of work-related asthma is doubled if you grow up in an urban environment and become a farmer as an adult.

The researchers have been monitoring all the students of agricultural science in Denmark from two different year groups and for 15 years – a total of 2,000 students. And the process has been performed on a regular basis, which makes this study unique.

“We now know that children who grow up in this kind of agricultural environment are protected until the age of 20-25, and there are many indications that the effect lasts even longer than this,” explains Professor Torben Sigsgaard from the Institute of Environmental and Occupational Medicine at Aarhus University.

“The perspectives of this study mean that if we can identify the mechanism involved and then find out how to have an influence on it, we may be able to help a great number of people in all walks of life,” he says.

The study should be seen in the light of the fact that farmers in general have a greater risk of suffering from asthma and chronic bronchitis.