Air pollution has always been problematic for people with allergies and asthma, but new Canadian research shows that exposure to traffic-related pollution in the first year of life could actually increase a child’s chances of developing allergies to foods, mold, pets and pests.
Researchers looked at data from more than 2,400 children, and skin-tested them for 10 common allergens including cat, dog, dust mite, cockroach, milk, egg, soy and peanut at one year of age. They also measured levels of nitrogen dioxide, a key component of traffic pollution, in their homes in four Canadian cities.
What they found was that those who became sensitized to allergens tended to have higher exposure to traffic exhaust. And while other studies have linked heavy traffic with asthma in kids, this new research is the first to link air pollution and measured allergic sensitization during some of the earliest stages of life.
“This is a really early look. Most of the studies that have been done to date have looked at age 2, age 4, age 6,” says co-author Michael Brauer, a professor in the School of Population and Public Health at the University of British Columbia.
The researchers also found that the kids who were least likely to develop sensitivity to allergens were those who had siblings and/or pets, who attended daycare, and who lived in a home with an unattached garage.
So why would exhaust trigger allergies in babies? Brauer says they haven’t landed on a firm answer yet, but researchers are investigating three key theories: that pollution is somehow making cell membranes more permeable to allergens; that exhaust affects newborns at the genetic level, and alters key pathways; or that the pollution chemically reacts with proteins from the allergens.
The study is part of the ambitious Canadian Healthy Infant Longitudinal Development Study (CHILD), which is tracking more than 3,500 families and their infants over several years to help determine the root causes of allergies and asthma. Along the way, researchers within the AllerGen network are collecting myriad samples from blood to urine to breast milk, and examining everything from families’ daily habits to the components of their house dust. They will continue following the kids to identify patterns that emerge over time.
Still, it’s never too soon to avoid pollution. “We don’t have any evidence that air pollution is good for you, so I’m not too cautious about recommending that you reduce your exposure to it,” says Brauer, who adds that in future, city planners may even need to create pedestrian and cycling routes away from heavy traffic streets.
“People are choosing where they live based on price, on the quality of schools, on a number of other factors. Especially if you have a history of respiratory disease or allergy, this may be another thing you want to think about.”
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