Traffic pollution ups allergy risk

[Posted: Mon 16/06/2008]

The risk of allergies and atopic diseases, such as eczema, has risen significantly among children because of traffic-related pollution, the results of a new study indicate.

German researchers examined almost 2,900 children at the age of four and over 3,000 children at the age of six, in order to determine their rates of doctor-diagnosed asthma and/or allergies, in relation to long-term exposure to traffic-related pollution.

Their exposure to pollution was calculated by taking into account the distance of their homes from major roads when they were born and at the ages of two, three and six. Their parents were also given questionnaires about the children’s respiratory diagnoses and symptoms.

All of the children were assessed for asthma, wheezing, sneezing and eczema. At six years of age, they were assessed for food allergies. Meanwhile the air was also tested regularly at 40 points near high traffic areas.

The researchers found a positive link between the distance to the nearest road and asthmatic bronchitis, hay fever, eczema and allergic sensitisation. They also found a link between the proximity to the road and the risk of allergic sensitisation. In fact, those who lived closest to major roads had an almost 50% greater risk of allergic sensitisation, compared to those who lived furthest away.

“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 more freshly emitted aerosols which may be more toxic.

“Our findings provide strong evidence for the adverse effects of traffic-related air pollutants on atopic diseases, as well as on allergic sensitisation,” explained lead researcher, Dr Joachim Heinrich at the Institute of Epidemiology in Munich.

The results stood even after other factors were taken into account, such as parental allergies and pet ownership.

"We consistently found strong associations between the distance to the nearest main road and the allergic disease outcomes. Children living closer than 50 metres to a busy street had the highest probability of getting allergic symptoms, compared to children living further away,” Dr Heinrich said.

Details of these findings are published in the American Journal of Respiratory and Critical Care Medicine.

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