(NaturalNews) Young children who live on tree-lined streets have lower rates of asthma than children living on streets with less vegetation, according to a new study conducted by researchers from Columbia University.
Little research has previously been conducted between the connection between trees and asthma rates, but the question is of particular importance as asthma rates continue to rise. The prevalence of the disease has increased steadily since 1980, especially in inner cities.
Some researchers have suggested that trees cleanse the air and encourage children to play outdoors, which improves their overall health. But others have speculated that pollen from trees might actually trigger asthma attacks.
In the current study, researchers compared asthma rates among children aged four and five in different neighborhoods of New York City in 1999 with the density of trees in those neighborhoods, based on a 1995 census. They found that the wealthy Upper East side, with 1,675 trees per square kilometer (seven trees per acre) had the most trees, while the poor Hunt's Point-Mott Haven neighborhood had the lowest, at 109 trees per square kilometer (0.441 trees per acre). To distinguish between an effect caused by trees and one caused by differences in wealth, the researchers adjusted for the percentage of residents in each neighborhood living below the poverty line. They also corrected for the nearby pollution sources, including busy truck routes.
Even after these adjustments, a higher density of trees correlated with a lower incidence of asthma: For every extra 343 trees per square kilometer (1.5 trees per acre), asthma rates decreased by 29 percent.
"We think that trees might have a beneficial effect on air quality - affecting air quality right at the street level," said researcher Gina S. Lovasi.
Lovasi noted that it still remains to be determined if the trees themselves are bringing down asthma rates, or if they are merely a marker for a healthier overall environment.