April 1, 2012

Making the case for green streets

City planners and health professionals take note: The case for greening our cities has been made.


What researchers, horticulturists and parks professionals have long suspected to be true can now be proven — nature has healing powers, and is essential to healthy human habitats.

Leading the charge on this new way of thinking is Dr. Frances ‘Ming’ Kuo, faculty member at the University of Illinois at Urbana-Champaign. Among her responsibilities is directing the Landscape and Human Health Lab. Dr. Kuo spoke at the Royal Botanical Gardens in Burlington, Ont., as part of a two-day Back To Nature workshop. Her keynote presentation was well-received, with lots of participation from an engaged audience.

In the last 10 years, a lot of work has been done looking at the effects of nature in many different forms and on many different populations around the world. Dr. Kuo was careful to point out that all research has been done to rigourous standards, taking income and other advantages into account. “We know that people living in greener neighbourhoods have better health outcomes,” she said. She went on to explain that even once income and other advantages associated with living in green neighbourhoods are taken out of the equation, studies prove residents will still have a better health outcome if they live in an area with trees.

Dr. Kuo proposes a new way of thinking, backed up with extensive studies—that nature is essential to a healthy human habitat, and its effect helps save money spent in the health care system. Trees in the urban landscape aren’t just the parsley around the roast, as Thomas Church,  a landscape architect famously quipped. They are a necessity. Ethology (the study of animal behaviour) has shown that poor animal habitats will result in social, psychological and physical breakdown. Twenty-five years of research has shown that humans like environments that include natural elements, so Dr. Kuo set out to determine if humans deprived of nature will undergo social, psychological and physical breakdown.

Social effects
Dr. Kuo offered multiple research studies that proved each of her points. A study of the social effects of green spaces was conducted through Chicago Public Housing Authority sites. The housing authority owns a number of similarly designed properties surrounded by varying degrees of greenery — to which residents are assigned (fortuitously for Dr. Kuo’s purposes) on a completely random basis. Her research showed that aggression, violent crime, graffiti and illegal activities all decreased in areas where there were planted greenspaces. Residents housed in barren environments exhibited feelings of loneliness, provided less supervision of children outdoors, showed less courtesy and mutual support, and revealed a weakened sense  of community.

Psychological Effects
Numerous studies prove that greenspaces help improve attention, learning and impulse control in children, and decrease symptoms of attention deficit/hyperactivity disorder (AD/HD), clinical depression and anxiety attacks. In one study, children with AD/HD were taken on guided walks in each of three different settings: a neighbourhood, a downtown area and an urban park. After each walk the children were taken indoors and given concentration tests. Despite the order in which the walks were taken, the children’s concentration was significantly better after the walk in the park — equal to or greater than the peak performance boost obtained by taking commonly prescribed medications for AD/HD.

Dr. Kuo has looked at years of standardized testing results in Chicago schools. Schools that had poor test results improved substantially over a 10-year period during which the city invested in schoolyard greening.

Physical Effects
A tree a day might help keep the doctor away.

Diabetics exercising in a forested setting saw a 74-unit drop in blood sugar, while only experiencing a 14-unit drop if cycling indoors. Residents in the Netherlands living within one kilometre of a greenspace showed significantly less frequent occurrence in 15 out of 24 prevalent diseases. A study of elderly Tokyo residents revealed that, taking into account the individual’s age, sex, marital status, socioeconomic status and health status, those living near a walkable green space enjoyed a longer life. They also reported better functionality and independent living skills.

Concluding her talk, Dr. Kuo pointed out that she only focused on the large body of evidence proving nature is essential to healthy human habitat. She noted that she hadn’t even touched on the many other benefits greening brings to cities such as cleaner air, replenished oxygen, absorption of carbon dioxide, and energy cost savings, to name a few. Her substantive findings are being used to help prove to city planners that plant life is a vital component of neighbourhoods and should be integrated in design to encourage communities that are resilient, effective, caring and healthy.

For further information and research citations, download the Parks and Other Green Environments monograph prepared by Dr. Kuo for the National Recreation and Parks Association, available at www.nrpa.org.