Oct. 19, 2000 -- Children are often sent outside to "get some fresh air," but in Los Angeles and other areas where the air is not so fresh, that could be dangerous advice. A new study suggests that kids living in high-smog areas have diminished lung development, which may impact their health as adults.
Researchers compared lung development in a group of children living in high-pollution areas in and around Los Angeles, which has the highest levels of air pollution in the country, with that of children living in low-pollution areas some 100 miles away. Those in the high-pollution group showed decreases in lung function growth for each year studied. And the negative impact of exposure to smog was greater for children who spent more time outside.
"This is the largest and most comprehensive study to date looking at the long-term effects of air pollution on the respiratory health of children," study author W. James Gauderman, PhD. says. "Although air pollution levels have been coming down over the last couple of decades in Los Angeles, there is still more work to be done. And with bigger cars on the road, and more people coming to the area, keeping a tight control on emissions could have a significant impact on the health of children."
The study represents perhaps the most convincing evidence yet that air pollution has long-term negative consequences on lung development of children. It has long been suspected that children are particularly vulnerable to the effects of smog because they tend to spend more time outside than adults and their lungs are not yet fully developed.
Diminished lung function growth ultimately could lead to an increased risk of chronic respiratory illness in adulthood, Gauderman tells WebMD. Gauderman is assistant professor of preventive medicine at the University of Southern California Keck School of Medicine in Los Angeles.
Henry Gong, MD, chief of environmental health services at Rancho Los Amigos Health Center in Downey, Calif., agrees. "This shows that even at everyday pollution concentrations that are considered much better than those seen 10 or 20 years ago, there is still an impact on health, especially for children," he says. Gong reviewed the study for WebMD.
In the study, Gauderman and colleagues performed lung capacity tests on more than 3,000 students living in and around Los Angeles each year for four years. Half of the students was in the fourth grade at the beginning of the study, one-quarter was in the seventh grade, and the remaining one-quarter was in the 10th grade.
While children living in the low-pollution counties north of Los Angeles showed normal lung function growth of around 12% a year, children living in the high-pollution communities lagged by about 1% per year, Gauderman says. By the end of the four-year study period, children living in the most polluted areas had a reduction of 3.4% in a measure that looks at lung capacity and a 5% reduction in a measure that accesses airflow in the lungs.
"Reductions of 3.4% and 5% do not seem like much, but one has to remember that we are talking about growing lungs," Gong says. "We don't know what the long-term effects of this delayed maturation will have on adult health."
Gauderman explains: "What happens with lung growth is that capacity will grow in females until about age 18, and in males until the early 20s. Then growth plateaus for about 10 years, and beginning in the late 20s both males and females start to lose function. These kids in the higher-pollution communities may be plateauing at a lower level, suggesting that they will have lower lung function as adults."
The USC researchers are still following the children who have not graduated from high school, and they plan to publish data after eight years of follow-up. They also hope to find funding to follow the group into adulthood, in an effort to document the long-term effects of air pollution on their lung function.