Wednesday, July 09, 2008

Pollution Triggers Children's Allergies, Diseases

(previously published here at

Living near roads that are heavily trafficked and polluted increases a child's risk of developing physician-diagnosed asthma, allergies and atopic diseases (chronic skin diseases) by more than 50 percent, a new study finds.

The 17-month study by researchers from Germany's Center for Environment and Health at the Institute of Epidemiology was based on the idea, as described by the lead author Joachim Heinrich, Ph.D, that "[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."

The study's results were published in the second June 2008 issue of the American Thoracic Society's American Journal of Respiratory and Critical Medicine. In his summary, Dr. Heinrich considers them to "provide strong evidence for the adverse effects of traffic-related air pollutants on atopic diseases as well as on allergic sensitization."

This is the first study to report an association between allergic sensitization and pollution levels. Previous studies done in the United States found links between the two, but took into account various socioeconomic, environmental and behavioral factors that are also associated with life in urban areas, making a causal relationship between pollutant exposure and allergic risk impossible.

Socioeconomic variables in U.S. studies over the past two years include the effect of diesel exhaust particles on airborne allergenic particles, environmental variables include ozone levels, and behavioral factors include recreational time spent indoors instead of outdoors.

Researchers for this study, however, say that older European cities like Munich, where the study was conducted, have roads and buildings that are established in a way that makes it possible to eliminate a correlation with economic advantages or disadvantages.

Approximately 2,900 four-year-olds and over 3,000 six-year-olds who had been born and were enrolled in school in the metropolitan area of Munich, Germany, were examined over the course of the study. The children's long-term exposure to traffic pollutants were calculated as a function of the distance from their houses to the major roads at birth and at ages two, three and six. Control groups were used to account for individual circumstances such as pet ownership, pet allergies and number of siblings.

Parents filled out questionnaires about their child[ren]'s respiratory diagnoses and symptoms while children were evaluated for asthma, sneezing, wheezing and eczema. At age six, all of the children were tested for food allergies. In addition, the air in each of 40 identified points near high traffic areas was tested for smog, soot and other particulate matter, as well as nitrogen oxide (NO2) once per season between March 1999 and July 2000.

On top of the 50 percent greater risk of allergic sensitization, the results found strong positive links between the distance of the nearest road and diseases such as hay fever, asthmatic bronchitis, eczema and allergic sensitizations. Also, children who lived within half a block (50 meters/164 feet) to a busy street had the highest probability of getting symptoms, compared to children living further away.

Heather Chin can be reached at

©The Evening Bulletin 2008

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