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Environmental Factor, April 2015

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Children’s lungs grew stronger as air pollution declined in Southern California

By Carl Marziali

Headshot of James Gauderman

Gauderman cautioned, “We can’t get complacent, because not surprisingly, the number of vehicles on our roads is continually increasing. Also, the activities at the ports of LA and Long Beach, which are our biggest polluting sources, are projected to increase.” (Photo courtesy of the University of Southern California)

A 20-year study, published March 5 in the New England Journal of Medicine, found that millennial children in Southern California breathe easier than ones who came of age in the 1990s. The University of Southern California (USC) Children’s Health Study, funded in part by NIEHS, measured lung development between the ages of 11 and 15 and found large gains for children studied from 2007 to 2011, compared to children of the same age, in the same communities, in the periods 1994-1998 and 1997-2001.

The gains in lung function paralleled improving air quality in the communities studied, and across the Los Angeles (LA) basin, as policies to fight pollution took hold.

By following more than 2,000 children in the same locations over two decades, and adjusting for age, gender, ethnicity, height, respiratory illness, and other variations, the study provided strong evidence that improved air quality by itself brings health benefits.

“We saw pretty substantial improvements in lung function development in our most recent cohort of children,” said lead author James Gauderman, Ph.D., professor of preventive medicine at USC.

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“These solid scientific results demonstrate some of the ways that reducing air pollution provides significant health benefits to children, who are some of our most vulnerable citizens,” said Kimberly Gray, Ph.D., who oversees grants to the NIEHS/EPA Children’s Environmental Health and Disease Prevention Research Centers.

Bigger lungs, better function

Combined exposure to two harmful pollutants, nitrogen dioxide (NO2) and particulate matter with a diameter of less than 2.5 microns (PM2.5), fell approximately 40 percent for the third cohort of 2007-2011 compared to the first cohort of 1994-1998. The study followed children from Long Beach, Mira Loma, Riverside, San Dimas, and Upland.

Children’s lungs grew faster as air quality improved. Lung growth from age 11 to 15 was more than 10 percent greater for children breathing the lower levels of NO2 from 2007 to 2011 compared to those breathing higher levels from 1994 to 1998.

The percentage of children in the study with abnormally low lung function at age 15 dropped from nearly 8 percent for the 1994-1998 cohort, to 6.3 percent in 1997-2001, to just 3.6 percent for children followed between 2007 and 2011 (see images below).

The growing years are critical for lung development. The researchers are also monitoring lung function in a group of adults who participated in the study as adolescents. So far, they have not found evidence of a rebound after the teenage years. “Their lungs may have lost the opportunity to grow any more,” Gauderman suggested.

Broad benefits from better air

Across all five communities, lung development for children with asthma improved roughly twice as much as for other children. But even children without asthma showed significant improvements in their lung capacity, suggesting that all kids benefit from improved air quality.

"We expect that our results are relevant for areas outside southern California, since the pollutants we found most strongly linked to improved health ­— nitrogen dioxide and particulate matter — are elevated in any urban environment," Gauderman said. “Our results suggest that better air quality in future will lead to even better lung health,” he said.

Citation: Gauderman WJ, Urman R, Avol E, Berhane K, McConnell R, Rappaport E, Chang R, Lurmann F, Gilliland F.2015. Association of improved air quality with lung development in children. N Engl J Med. 372(10):905-913.

(Carl Marziali is assistant vice president for media and public relations at USC. This story is based on the USC press release.)

Graph that shows As pollution declined, Children's lung function improved

Graph that shows As pollution declined, Children's lung function improved

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