Besides obscuring the view, hazy air filled with car exhaust, dust and smoke can slow the development of adolescent lungs, a new study suggests. The report, published in the December issue of the American Journal of Respiratory and Critical Care Medicine, shows that children's lung performance is affected by the amount of particulate air pollution in their community.

Edward L. Avol of the University of Southern California and colleagues began their study by testing the lung function of adolescents living in Southern California, measuring how much air the subjects could expel and how quickly. "Lung function typically peaks in your 20s and then slowly declines with age," Avol explains. "So what happens during that big growth spurt during the teen years may be especially important later in life." Five years later, the researchers then retested the 110 children who had moved to other communities in California, Oregon, Nevada, Washington, Arizona and Utah. They found that students who had relocated to areas with lower levels of particulate matter experienced increased lung function growth. Those who moved to areas with more particulate pollution, in contrast, exhibited a slowdown in lung function growth. The differences were most striking in students who had lived in their new area for more than three years. "This study confirms our earlier work showing that air pollution can have long-term effects on lung health in children," Avol notes.

Current thinking suggests that children who experience decreased lung function could prove more susceptible to respiratory disease or be more likely to have chronic respiratory difficulties as adults. The researchers plan to continue monitoring the children to investigate any persistent and long-term effects air pollution may have. But Avol would like prevention strategies in place now. The current study, he says, "shows that cleaning up the air actually has a measurable effect on children's health."