Exposure to traffic pollution and indoor allergens multiplies the risk of asthma in high-risk children

A study, published in the December 1, 2009, edition of the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine, University of Cincinnati College of Medicine suggests that children who are exposed to high levels of traffic-related pollution and high levels of indoor allergens early in life have six times the risk of developing persistent wheezing by age three than children who aren’t. These two exposure sources, when simultaneously present at high levels, appear to work synergistically to damage the developing lungs of young children.

In the study, 624 children at high allergic risk with at least one atopic parent completed a clinical examination, exposure and symptoms questionnaires and skin prick tests for allergy at years one, two and three. The researchers used land-use regression modeling to calculate study participants' exposures to traffic-related particles, such as diesel exhaust and home visits to sample the levels of indoor allergen exposure.

Of the children studied who were exposed to high levels of both traffic-related pollution and indoor allergen, more than 36% demonstrated persistent wheezing at age three, an early warning sign of asthma and other pulmonary conditions. In contrast, in children exposed to low levels of both indoor and outdoor allergens, only 11% experienced wheezing. Among children exposed to low levels of indoor allergens but high levels of traffic-related particles, 18% demonstrated persistent wheezing, but allergen exposure alone appeared to have little effect.

The earlier in life this type of exposure occurs, the researchers warned, the more impact it may have long term. Lung development occurs in children up through age 18 or 20. Exposure earlier in life to both allergen and traffic will have a greater impact on developing lungs compared to adults whose lungs are already developed.

For the full research paper

First Published in november 2009

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