A study of nearly 6,000 children in Munich has found that children are much more likely to develop asthma, allergies and skin rashes if they live near major roads.
Vehicle tailpipes emit nitrogen oxides, volatile organic chemicals and fine particulates (soot). While U.S. laws have cracked down on the worst polluters, diesel engines, air quality near major roads is knwon to be worse than in other areas.
The study, by Joachim Heinrich of the German Research Center for Environment and Health at the Institute of Epidemiology, is to be published in American Journal of Respiratory and Critical Care Medicine, a publication of the Thoracic Society.
"[Children] living very close to a major road are likely to be exposed not only to a higher amount of traffic-derived particles and gases but also to a more freshly emitted aerosols which may be more toxic," Heinrich writes. "Our findings provide strong evidence for the adverse effects of traffic-related air pollutants on atopic diseases as well as on allergic sensitization."
The study focused on four- and six-year-olds, and controlled for other factors that might influence lung health, like socioeconomic status, the presence of a pet in the home, parental allergies and the number of siblings sharing the home.
Even eliminating those causes, the road had an important influence on the children's health. Proximity was linked to asthma, hay fever, eczema and allergic sensitizations.
How close is too close?
Those children living within about 165 feet of a major road had a 50% greater chance of developing allergies.
"We consistently found strong associations between the distance to the nearest main road and the allergic disease outcomes," Heinrich wrote. "Children living closer than 50 meters to a busy street had the highest probability of getting allergic symptoms, compared to children living further away."