US scientists suggest that children who grow up near busy roads or highways with traffic pollution have poorer lung function and are more likely to suffer long term respiratory and heart-related health problems than those who live further away.

The study is published in the early online edition of the Lancet.

The research team was led by Dr James Gauderman, Associate Professor of Preventive Medicine at the Keck School of Medicine of the University of Southern California. His team comprised ten other academic and industry scientists from California and Spain.

The scientists examined the effects of traffic pollution on 3,677 children who grew up in Southern California over an 8-year period between the ages of 10 and 18. They drew on data that had been collected as part of the longitudinal study known as the Children's Health Study, which has been monitoring respiratory health among children in 12 Southern California communities. The communities had differing levels of air quality.

The results showed that the lungs of the kids who had lived within 500 metres (about 500 yards) of a busy highway or road with traffic pollution were less developed and had lower lung capacity than those who had lived at least 1,500 meteres away.

Dr Gauderman said in a prepared statement that a person who has been breathing in that level of pollution in their growing years is likely to have poorer lung function the rest of their life. It is already known that poorer lung function is a risk factor for developing cardiovascular and respiratory diseases such as emphysema in later adult life.

"Otherwise-healthy children who were non-asthmatic and non-smokers also experienced a significant decrease in lung function from traffic pollution," said Dr Gauderman, and he suggests that "all children, not just susceptible subgroups, are potentially affected by traffic exposure."

For each year over the 8-year period scientists tested the lung function of each child, such as how forcefully they could breathe out and how much volume of air they could breathe out and take in. They also recorded how far away the child's home was from busy roads and highways and took into account the air quality and level of traffic pollution in each case.

Living near traffic pollution means that more of the ultrafine particles and carbon emitted from vehicle exhausts, particularly from diesel fumes, get deep into the lungs. Toxic chemicals are also present in traffic pollution, such as nitrogen dioxide which affects the ability of the lungs to exchange oxygen and carbon dioxide with the bloodstream.

"This study shows there are health effects from childhood exposure to traffic exhaust that can last a lifetime," said Director of the National Institute of Environmental Health Sciences, David Schwartz.

"Someone suffering a pollution-related deficit in lung function as a child will probably have less than healthy lungs all of his or her life," added Dr Gauderman.

The researchers suggest that this study adds further support to the argument that regional air quality regulations will have to be adjusted to take in local factors, including how traffic volume affects air quality. This is particularly important in areas where because of population growth, communities are building schools and homes near to busy roads and highways. This study shows there is likely to be a significant impact on child and adult public health if this trend is allowed to continue.

"Effect of exposure to traffic on lung development from 10 to 18 years of age: a cohort study."
Dr W James Gauderman PhD, Hita Vora MS, Prof Rob McConnell MD, Kiros Berhane PhD, Prof Frank Gilliland MD, Prof Duncan Thomas PhD, Fred Lurmann MS, Edward Avol MS, Nino Kunzli MD, Michael Jerrett PhD and Prof John Peters MD.
The Lancet Early Online Publication, 26 January 2007.

Click here for Abstract (free subscription).

Factsheet (PDF) for parents on traffic pollution and children's health (Office of Environmental Health Hazard Assessment, California).

: Catharine Paddock
Writer: blog

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