A first-of-its-kind study in California reports dramatically better lung function growth with improved air quality.
The study involving of 2,120 children over a 13-year period showed the proportion of children with poor lung capacity and lung health in southern California fell by half with a reduction in the levels of nitrogen dioxide and particulate matter. The improvements were seen in youngsters that had asthma and in those who did not, said Reuters.
The study complements research showing childhood lung function worsens and the risk of asthma rises as pollution levels increase. It was published in the New England Journal of Medicine.
California has the strictest air pollution standards in the United States. The U.S. Environmental Protection Agency has adopted California's emissions standards as a national standard by the 2016 model year in cars. It is also collaborating with California regulators on stricter national emissions standards for model years 2017 to 2025.
The air improved "dramatically" in southern California during the study years. From 1994 to 1997, each cubic meter of air in Mira Loma, one of the most-polluted communities, had 31.5 particles called PM2.5 that penetrate deep into the lungs.
From 2007 to 2010, Mira Loma averaged 17.8 micrograms of PM2.5 per cubic meter of air, a 43 percent decline. All five study sites had significant drops in particle pollution and nitrogen dioxide, they note.
Overall, average lung capacity increased by 91.4 milliliters for every decrease of 14.1 parts per billion in nitrogen dioxide, a toxic, large scale pollutant produced by cars running on gasoline. It rose by 65.5 ml for each decrease of 8.7 micrograms per cubic meter of particle pollution.
"It certainly supports the efforts that have been made over 40 years to improve air quality," said study chief author Dr. James Gauderman of the Department of Preventive Medicine at the University of Southern California in Los Angeles.
"We would expect improvements in other urban centers to produce similar improvements in children's health."
Dr. Gauderman and his team examined the long-term effects in children by studying three groups during three time periods between 1994 and 2011. On average, most of the children entered the study around age 11. They were followed for four years, a period during which lungs develop rapidly. All the children lived in the Los Angeles area, a region of the U.S. known for air pollution problems.
"We looked at the proportion of children whose lung function was below 80 percent of normal. That's a cutoff a physician will often use to flag a person for a possible issue with their lungs," Dr. Gauderman said.
While 7.9 percent of children fell into that category in 1998, the proportion fell to 3.6 percent by 2011.
"We certainly suspected that improving air quality would improve children's health," Dr. Gauderman said. "We were surprised by the magnitude of the effect that we've seen."