What stroller-pushing mothers negotiating urban traffic jams have long suspected, a new study shows, is true: children living near major motorways run a greater risk of growing up with damaged lungs. The link between air pollution and respiratory ailments is well established, but the eight-year study of more than 3,600 children in Los Angeles provides compelling evidence, for the first time, that small distances can make a huge difference when it comes to measuring the health hazards of vehicle exhaust. Ten-year olds growing to adulthood within 500 meters (yards) of a freeway were far more likely to have stunted lung development than their cohorts living an additional 1000 meters distant, a team of American researchers led by W. James Gauderman of the University of Southern California conclude in a paper published Thursday in the British journal The Lancet. "The study points to a several-fold increase (between groups) in the number of children showing substantial reduction in lung function," Dr. Thomas Sandstrom, a professor in the Department of Respiratory Medicine at the University Hospital in Umea, Sweden, commented by phone. "What is worrisome is the heightened risk of lung disease" ranging from increased rates of asthma to more serious, potentially fatal illnesses, added Sandstom, who also wrote a commentary on the study in Lancet. The close proximity to vehicle exhaust does not only affect those with frail lungs, the scientists said. "Otherwise-healthy children who were non-asthmatic and non-smokers also experienced a significant decrease in lung function from traffic pollution," said Gauderman. The study's findings also raise troubling questions about what the authors call "environmental equity" because -- even within a single community -- some children are at higher risk than others. "The present regulatory emphasis on regional air quality might need to be modified to include considerations of local variation to air pollution," it suggests. The study was based on the yearly testing of 3,677 children, from 12 Los Angeles communities, over an eight-year period beginning from the age of ten. Lung function was measured by seeing how much air each child could exhale -- and how quickly -- after taking a deep breath, along with other tests. The children were divided into three groups depending on how close they lived to a freeway, as multi-lane expressways are called in California: less than 500 meters, between 500 and 1000 meters, and between 1000 and 1500 meters. Researchers adjusted the results for other variables that could have influenced lung performance, such as smoking or asthma, as well as the weight, height and body-mass index of each child. Also factored out were broader variations in air quality, but "even in an area with low regional pollution, children living near a major roadway are a increased risk of health effects." Several elements in vehicle exhaust can damage lung tissue, but the most harmful are nanoparticles with organic hydrocarbon components on the surface, present in far higher concentrations near freeways. "The study suggests that there may be something in particular about primary emissions -- fresh emissions -- that are particularly dangerous" as compared to settled pollution, said Sandstrom. "We don't know enough about the toxic effect of primary traffic emissions," he said, adding that this paper could influence deliberations currently underway in the European Union on funding priorities for research on pollution. Also of special interest to Europeans is the study's conclusion that diesel fuel -- far more common in Europe than the United States -- is especially hazardous because of its high concentration of particulate-matter.


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