What many people have known for awhile — that experiencing nature and the outdoors benefits our mental and physical health — is increasingly buttressed by research, according to a leading researcher who has worked with the U.S. Congress and the Centers for Disease Control and Prevention.
“Through the decades, parks advocates, landscape architects, and popular writers have consistently claimed that nature had healing powers,” said University of Illinois environmental and behavioral scientist Dr. Frances (Ming) Kuo. “But until recently, their claims haven’t undergone rigorous scientific assessment.”
A wealth of new studies has provided firm evidence for going green, she said. For example, objective data confirming the benefits of natural settings has been collected for disparate sources including police crime reports, blood pressure, performance on standardized neurocognitive tests, and physiological measures of immune system functioning.
“Researchers have studied the effects of nature in many different populations, using many forms of nature,” Kuo said.
“They’ve 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.”
According to Kuo, the rigor and thoroughness of the studies sets them apart and gives firm evidence of the green benefits.
“In any field with enthusiasts, you will find a plethora of well-meaning but flimsy studies purporting to ‘prove’ the benefits of x,” Kuo said. “But in the last decade or so, rigorous work on this question has become more of a rule than an exception. The studies aren’t simply relying on what research participants report to be the benefits of nature.”
A shift of focus to population health, an approach that recognizes the need for health strategies that shift or improve the health of large groups of people, is essential for improving the nation’s well-being.
Kuo said that 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.
“The question has become, do people living in greener neighborhoods have better health outcomes when we take income and other advantages associated with greener neighborhoods into account?” That answer is yes, according to Kuo.
Health promotion specialists say green environments provide natural recreational and physical playscapes for all ages, enhancing fitness while relieving stress.
Kuo drew an analogy to animals. “Just as rats and other laboratory animals housed in unfit environments undergo systematic breakdowns in healthy, positive patterns of social functioning, so do people,” she said.
“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.
“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 said. “We also find more evidence of loneliness and more individuals reporting inadequate social support.”
Research findings include:
- Access to nature and green environments yields better cognitive functioning, more self-discipline and impulse control, and greater mental health overall.
- Less access to nature is linked to exacerbated attention deficit/hyperactivity disorder symptoms, higher rates of anxiety disorders, and higher rates of clinical depression.
Kuo noted the impacts of parks and green environments on human health extend beyond social and psychological health outcomes to include physical health outcomes.
- 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,” she said.
Because of this strong correlation between nature and health, Kuo encouraged city planners to design communities with more public green spaces in mind, not as mere amenities to beautify a neighborhood, but as a vital component that will promote healthier, kinder, smarter, more effective, more resilient people.