Kids who grow up on farms are far less likely to develop asthma or allergies compared with the average child — and now scientists think they know why. A study published in Science today shows that bacteria found in farm dust trigger an immune system response in the lungs of mice.

Source: http://www.theverge.com/2015/9/3/9256955/allergies-asthma-farm-kids-dust-endotoxins-a20