Washington: Researchers have shown for the first time that reducing air pollution leads to improved lung function in children ages 11 to 15.
A 20-year study found that millennial children in Southern California breathe easier than youngsters who came of age in the 1990s, for a reason as clear as the air in Los Angeles on Thursday, researchers said.
The University of Southern California (USC) Children's Health Study 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 from 1994-98 and 1997-2001.
The gains in lung function parallelled improving air quality in the communities studied and across the Los Angeles basin, as policies to fight pollution took hold, researchers said.
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 provides stronger evidence that improved air quality by itself brings health benefits - the kind that last a lifetime for children breathing cleaner air during their critical growing years.
"We saw pretty substantial improvements in lung function development in our most recent cohort of children," said lead author W James Gauderman.
Previous findings from the study showed an increase in stunted lung development for children in areas with heavy air pollution, as well as a higher risk of asthma for children living near busy roadways.
Combined exposure to two harmful pollutants, nitrogen dioxide (NO2) and particulate matter of diameter under 2.5 microns (PM2.5) fell approximately 40 per cent for the third cohort of 2007-11 compared to the first cohort of 1994-98. 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 per cent greater for children breathing the lower levels of NO2 from 2007 to 2011 compared to those breathing higher levels from 1994-98.
The percentage of children in the study with abnormally low lung function at age 15 dropped from nearly 8 per cent for the 1994-98 cohort to 6.3 per cent in 1997-2001 and to just 3.6 per cent for children followed between 2007 and 2011.
That compares to 2.5 per cent by age 18 for children from the first two cohorts who lived in cities with cleaner air, such as Lompoc and Santa Maria.
"Reduced lung function in adulthood has been strongly associated with increased risks of respiratory disease, cardiovascular disease and premature death," Gauderman said.
"Improved air quality over the past 20 years has helped reduce the gap in lung health for kids inside, versus outside, the LA basin," Gauderman added.