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Editorial> Tree Cities, USA
Chris Bentley on the health benefits of urban tree hugging.
John W. Iwanski / Flickr

Riverwalks, rails-to-trails, community gardens, native plants—cities around the country, and especially in the Midwest, are embracing nature as a design partner. Once considered flighty ornamentation, trees, parks, and green infrastructure may actually have a positive impact on human health.

New research backs up the age-old assumption that fresh air is good for you, measuring positive impacts on public health from trees and green spaces. This matters in the Midwest, where vacant lots can be a creeping blight or an abundant resource. In Detroit, planners look to parks and public spaces to catalyze placemaking downtown. And Chicago has just outlined the Millennium Reserve, one of the nation’s largest open space projects, but its balance of open spaces, managed land, and industrial uses remains unclear.

A recent study by the U.S. Forest Service analyzed 18 years of data from nearly 1,300 counties and correlated the prevalence of emerald ash borers—an invasive beetle that decimates ash trees, common in many U.S. cities—with an additional 15,000 deaths from cardiovascular disease and 6,000 more deaths from lower respiratory disease when compared to unaffected areas. The research, published in The American Journal of Preventive Medicine, does not offer a causal link.

Another study, published in March in The British Journal of Sports Medicine, calculated the cognitive impacts of leafy backdrops on walkers and joggers using electroencephalograms, which measure brain waves. Though still a small study, their results confirmed the suspicion that green spaces lessen brain fatigue—the easily distracted, forgetful feeling that comes with constant exposure to chaotic sights and sounds. The Japanese practice of shinrinyoku, or “forest bathing,” has also been linked to health benefits in scientific studies.

Of course cities are not generally great places to grow trees. Pollution certainly plays a role—many former industrial sites are contaminated beyond their ability to sustain all but the hardiest of species—but open space is typically the greater limiting factor.

Chicago’s Millennium Reserve is ostensibly an open space project, but one with considerable swaths of land already devoted to industrial uses. Given the region’s historical disinvestment, new manufacturing jobs would be welcome. But as talk of development and sprawl shifts back to urban redevelopment and infill, we will have to balance density with green space. This can of course be done simultaneously—the ascendance of landscape architecture and tactical urbanism is encouraging on that front.

Charles Fraser, the real estate developer who reengineered South Carolina’s Hilton Head Island, famously called environmentalists modern-day druids, who “worship trees and sacrifice human beings to those trees.” But mounting evidence suggests that nature is as important to development as manmade infrastructure when it comes to sustaining healthy communities.

Chris Bentley