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Go green for nature’s healing powers

U. ILLINOIS (US) — City planners should design communities with more public green space, not simply for aesthetic reasons, but because they are a vital component to both physical and mental health.

“In greener settings, we find that people are more generous and more sociable. We find stronger neighborhood social ties, and greater sense of community, more mutual trust and willingness to help others,” says Frances “Ming” Kuo, environment and behavior researcher at the University of Illinois.

“In less green environments, we find higher rates of aggression, violence, violent crime, and property crime—even after controlling for income and other differences,” she says. “We also find more evidence of loneliness and more individuals reporting inadequate social support.”

Access to nature and green environments yields better cognitive functioning, more self-discipline and impulse control, and greater mental health overall, while less access is linked to exacerbated attention deficit/hyperactivity disorder symptoms, higher rates of anxiety disorders, and higher rates of clinical depression.

“Through the decades, parks advocates, landscape architects, and popular writers have consistently claimed that nature had healing powers,” Kuo says. “But until recently, their claims haven’t undergone rigorous scientific assessment.

“Researchers have looked at Chicago public housing residents living in high-rises with a tree or two and some grass outside their apartment buildings; college students exposed to slide shows of natural scenes while sitting in a classroom; children with attention deficit disorder playing in a wide range of settings; senior citizens in Tokyo with varying degrees of access to green walkable streets; and middle-class volunteers spending their Saturdays restoring prairie ecosystems, just to name a few.”

Although the diversity of the research is impressive, Kuo says, even more important is the rigor with which it is conducted.

“In any field with enthusiasts, you will find a plethora of well-meaning but flimsy studies purporting to prove the benefits of X,” Kuo says. “But in the last decade or so, rigorous work on this question has become more of a rule than an exception.”

The studies don’t simply rely on what research participants report to be the benefits of nature, she says, but use data that includes police crime reports, blood pressure, performance on standardized neurocognitive tests, and physiological measures of immune system functioning.

Rather than relying on small, self-selected samples of nature lovers such as park-goers, scientists are increasingly relying on study populations that have no particular relationship to nature.

One study examined children who were receiving care from a clinic network targeting low-income populations. Another looked at all United Kingdom residents younger than retirement age listed in national mortality records for the years 2001-2005.

Scientists are routinely taking into account income and other differences in their studies, Kuo says, so the question goes beyond simply asking if people living in greener neighborhoods have better health outcomes. (They do.)

The question becomes do people living in greener neighborhoods have better health outcomes when income and other advantages associated with greener neighborhoods are taken into account.  Studies show that that answer is also yes.

“We still find these benefits when they are measured objectively, when non-nature lovers are included, when income and other factors that could explain a nature-health link are taken into account. And the strength, consistency, and convergence of the findings are remarkable.”

Greener environments enhance recovery from surgery, enable and support higher levels of physical activity, improve immune system functioning, help diabetics achieve healthier blood glucose levels, and improve functional health status and independent living skills among older adults.

By contrast, environments with less green space are associated with greater rates of childhood obesity; higher rates of 15 out of 24 categories of physician-diagnosed diseases, including cardiovascular diseases; and higher rates of mortality in younger and older adults.

“While it is true that richer people tend to have both greater access to nature and better physical health outcomes, the comparisons here show that even among people of the same socioeconomic status, those who have greater access to nature, have better physical health outcomes.

“Rarely do the scientific findings on any question align so clearly.”

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