Here's the quick version of the findings:
- Asthma patients had more lung inflammation while strolling a busy street than in a park.
- If the air gets cleaner, lungs tend to act younger longer, even in people without asthma.
The studies are a "remarkable" look at air pollution's effects in the real world, states an editorial published with the studies in tomorrow's edition of The New England Journal of Medicine.
Asthma and Diesel Fumes
The first study took place in London's bustling Oxford Street and Hyde Park.
Oxford Street, London's busiest shopping area, only allows diesel-powered buses and taxis. Hyde Park doesn't allow any traffic on its 350 acres.
In the study, 60 adults with mild or moderate asthma spent two hours strolling along Oxford Street. More than three weeks later, they spent two hours walking in Hyde Park.
The researchers monitored the patients' lung function before, during, and after each walk. Those tests show more lung inflammation on Oxford Street than in Hyde Park.
During those walks, the air along Oxford Street was also grittier than the air in Hyde Park, based on real-time checks of fine particulates (a type of air pollution).
The patients didn't report any asthma symptoms during either walk. But people with more severe lung problems might be more affected, according to the researchers.
Imperial College's James McCreanor, MRCP, and colleagues aren't telling asthma patients to steer clear of Oxford Street.
But they say their study shows that the degree of traffic exposure matters in asthma patients' lung function.
Other factors -- including city stress on Oxford Street and the soothing scenery of Hyde Park -- may have affected the results.
Lungs Like Less Air Pollution
Don't have asthma? Your lungs may also appreciate a drop in air pollution.
Lung function typically declines with age. But that decline may happen more slowly when air pollution eases.
Swiss scientists report that news based on an 11-year study of more than 4,700 adults in Switzerland.
At the start and end of the study, participants took lung function tests. The researchers also checked air pollution levels in each participant's neighborhood.
Air pollution levels fell during the study. And the decline in lung function slowed with the decline in air pollution.
It didn't take a massive drop in air pollution for that to happen. Even "relatively small reductions" in particulates have "measurable benefits for lung function," write the researchers.
They included Sara Downs, PhD, of Switzerland's University of Basel.
In both studies, pollution levels were below the levels set by the World Health Organization and U.S. Environmental Protection agency, notes a journal editorial.
"These studies provide additional biologic data indicating that relatively low levels of airborne particles have adverse effects on human health. Are our standards too high?" asks Morton Lippmann, PhD, in his editorial.
Lippman works in the environmental medicine department at New York University's medical school.