The study, conducted by The Canadian Healthy Infant Longitudinal Development (CHILD), showed that the sensitivity to allergens was associated with exposure to traffic-related air pollution during infancy. Senior author Michael Brauer of the University of British Columbia said that with the increasing rates of allergies amongst children in Canada and elsewhere, they were interested in determining if air pollution from traffic might be partially responsible, adding that this is the first study to find a link between air pollution and measured allergic sensitisation during the first year.

While infants exposed to air pollution were at greater risk, researchers did not find a link between mothers exposed to air pollution during pregnancy and allergy risk in their children. The study also found that children who live with furry pets and no attached garage were more likely to have no sensitivity to allergens.

First author Hind Sbihi said that understanding which environmental exposures in early life affect the development of allergies can help tailor preventative measures for children, adding they also found that children who attended daycare or with older siblings in the household were less likely to develop allergic sensitisation, suggesting that exposure to other children can be protective.

The study is published in the journal Environmental Health Perspectives.