How Neighborhood Trees Improve Public Health

Alex Hutchinson writes of the larger implications of a new study published by the journal Scientific Reports into the nature of the therapeutic benefits of trees.

A team of researchers in the United States, Canada, and Australia, led by the University of Chicago psychology professor Marc Berman, collected two large data sets from the city of Toronto, according to Hutchinson, "both gathered on a block-by-block level; the first measures the distribution of green space, as determined from satellite imagery and a comprehensive list of all five hundred and thirty thousand trees planted on public land, and the second measures health, as assessed by a detailed survey of ninety-four thousand respondents." 

The study's findings: "an additional ten trees on a given block corresponded to a one-per-cent increase in how healthy nearby residents felt." Berman is quoted directly to add perspective:

'To get an equivalent increase with money, you’d have to give each household in that neighborhood ten thousand dollars—or make people seven years younger,' Berman told me.

A discussion of some of the study's subtler details, however, inspires Hutchinson to muse on large questions, like how the findings relate to a theory proposed by William James in the late 19th century about "voluntary" and "involuntary" attention. Berman's study produces a counter point to recent research identifying the negative effects of the urban tree canopy, as well as a chance for Hutchinson to propose a closer attention to the details of Berman's studies for the purposes of public health benefits.