The not-so-secret power of green spaces and how we benefit from them

On days where I find myself tethered to screens and technology for stretches of time, ditching the indoors and opting outside helps me clear my mind. Something about green spaces just makes me feel alive. Turns out, there might be some weight to this. In 2016, research associate Peter James and a team at Harvard University published a study that looked into the relationship between green spaces and mortality rates. “[Humans] certainly value nature inherently,” says James. “We’ve been trying in recent years to quantify that and understand it better.” According to James, the idea that nature restores your cognition and your mood have been around for a while. In 1984, American biologist E. O. Wilson coined the theory that humans evolved with nature to have an affinity for nature. Around this time, Japanese doctors also developed the practice of shinrin-yoku, or “forest bathing,” to prescribe to patients in order to lower heart rate and blood pressure. Since then, multiple studies have been conducted around the world that hint at the health benefits of being around nature. “But those studies all had some errors or some shortcomings,” explains James.

So James and his team studied 100,000 female nurses living across the U.S. over an eight-year period, using NASA satellite maps to measure the quantity of vegetation in given areas. “What we observed was that the participants who lived in the top quintile—the 20 percent of greenness—had, on average, about a 12 percent lower mortality rate over eight years, compared to the lowest quintile of greenness,” says James. “So, people who lived in the greenest areas tended to die at lower rates over this [period].” James and his team then became interested in learning what factors could explain the association between greenness and mortality. They then looked at the four main pathways that researchers consider for greenness to affect health: providing an opportunity for physical activity; lowering exposure to air pollution; increasing social engagement (people might be more likely to interact socially if they’re in a green area where people commonly gather); and mental health. In exploring the mental health factor, they gathered and measured information on self-purported, doctor-diagnosed depression and antidepressant medication from the study's participants.

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