Air in Southern California is cleaner than it was two decades ago, and a new study suggests children may be experiencing less respiratory problems because of it.
The study, published April 12 in the Journal of the American Medical Association, showed that kids living in eight Los Angeles-area communities today have stronger lung function compared to those who resided there in the 1990s.
Researchers, however, did not confirm that the decline in lung problems was solely due to the improvement in air quality.
“We’re careful to say this is an association. We can’t say it’s cause-and-effect for certain,” said lead researcher Kiros Berhane, a professor of preventive medicine at the University of Southern California.
A total of 4,602 children were involved in the study. Researchers monitored three groups: fourth graders from 1993 to their high school graduations in 2001, fourth graders from 1996 to 2004, and a group of kindergartners and first graders from 2003 to 2012.
The study was based on a variety of data including that on ozone, nitrogen dioxide and particulate matter for each year. Parents also provided regular updates on symptoms their children experienced, such as coughing and phlegm production.
Researchers found that in the 20-year period, “fine particle” pollution, which is emitted from cars and other industrial sources, fell by an average of 47 percent. Along with that decline came a 32 percent drop in “bronchitic” symptoms in children with asthma.
Associations in children without asthma were weaker, but were still significant.
“Clearly, the reduction in air pollution levels have translated into improvements in respiratory health,” said Berhane. “Especially for parents of children with asthma, this is very good news, but we see significant improvement in children without asthma as well.”
Based on that finding, Dan Greenbaum, president of Boston-based nonprofit organization Health Effects Institute, which helped fund the research, told United Press International that any steps taken to improve the health of children with asthma would have a significant public health impact.
“But this study suggests that above and beyond kids who’ve been diagnosed with asthma, there are subgroups of other children who are at risk from air pollution, and may benefit from better air quality,” he said.
The new findings come after a period of time that California has approved more stringent vehicle emissions standards.
Berhane said the latest research, however, don’t mean people should become complacent.
“In California, the number of cars on the road is always increasing,” Berhane said. “And we expect more activity at the large ports.
Los Angeles and other places in Southern California remain on the American Lung Association’s “most polluted cities” lists.