Cleaner air means healthier kids, pollution study finds

A new study shows that cleaner air has measurable health benefits for kids.

As air quality has improved in the notoriously smoggy Los Angeles area, so has the health of children's lungs, according to a long-running study of 2,120 children published today in The New England Journal of Medicine.

Researchers at the University of Southern California in Los Angeles compared three groups of children from ages 11 to 15, a critical time for lung function. Teens need to develop their lungs as fully as possible, because lung function tends to decline slowly but steadily after kids hit 18, says lead author James Gauderman, a professor of preventive medicine at the Keck School of Medicine at USC.

The first group of kids was studied from 1994 to 1998; the second from 1997 to 2001; the third in 2007 to 2011. Pollution levels fell about 40% from the time that researchers studied the first group of kids to the last, partly due to tough emission standards for cars, the study says.

Doctors evaluated children's lung function throughout the study by asking kids to exhale into an instrument, which measured how much air they could blow out.

At the beginning of the study, 7.9% of children had abnormally low lung function, meaning that their lungs were functioning at less than 80% of the normal level for their age, Gauderman says. By the time the last kids turned 15, the number with abnormally low lung function had fallen by more than half, to 3.6% of kids..

"Children are breathing better today because our air is cleaner," Gauderman says. "This is the first study to provide sound, scientific evidence that cleaning up our air actually improves the health of children."

That's an impressive achievement, Gauderman says, given that the number of cars and trucks driving on California roads has only grown in the past two decades.

Harold Farber, a pediatric pulmonologist at Texas Children's Hospital in Houston, called the research a "landmark study" because of the number of children involved and the length of time they were followed.

The findings bode well for the future health of today's children, Gauderman says. That's because greater lung function in adulthood is linked to a lower risk of premature death. In adults, those with reduced lung function are more likely to have chronic breathing problems and heart disease, according to an accompanying editorial by Douglas Dockery and James Ware of the Harvard T.H. Chan School of Public Health.

"Our research partly justifies efforts to clean up our air," Gauderman says. "This is an incredible environmental success story."

While studies have found that cleaner air can prevent premature deaths in adults, this is the first to find a major benefit for children, says the American Lung Association's Janice Nolen.

Nolen says it's important to maintain high standards for clean air in order to avoid losing these gains.

"Some have argued that the substantial improvements in air quality over the past 40 years are sufficient to protect public health and that there is little evidence to support more stringent standards," Dockery and Ware write. "However, the current report and other studies suggest that further improvement in air quality may have beneficial public health effects."