As people spend more time indoors, a mountain of scientific research says spending time in nature is critical to health and increases longevity. That means being in fresh air, under trees and away from cars and concrete—on a regular basis. And, no, the Peloton doesn’t count.
“There’s an urgent need emerging in science and at the gut level to increase the nature experience. This field is just exploding,” says Gretchen Daily, a professor of environmental science at Stanford University.
The benefits have been clear to scientists for some time, but the pandemic has made the matter more urgent. The physical and emotional toll the virus has taken, especially in urban areas with little green space, has galvanized doctors, researchers and others to tap into nature’s therapeutic effects.
Scientists have repeatedly found that human anticancer natural killer cells significantly increase after walks in a forest. In one such study, published in 2010 in the Journal of Biological Regulators and Homeostatic Agents, the number and activity of killer cells increased in a group of twelve healthy men after two walks, each two hours long, in a one-day trip to a forest park in the Tokyo suburbs. So did anti-cancer proteins, according to the research led by Qing Li, an associate professor at the Nippon Medical School. Cortisol in the blood and adrenaline in the urine significantly decreased. The effects lasted at least seven days, the researchers found.
Time in a forest is linked to decreased inflammation, which has been implicated in chronic disease.
“People are deciding whether or not this type of coffee bean or that type is better for you, when there is such an obvious health tool at your disposal. You literally just walk outside. People don’t know,” says Jared Hanley, co-founder and CEO of NatureQuant, a startup working on an app for users to track the time they spend in nature much like they count steps.
A study published in Nature’s Scientific Reports in 2019 found the 20,000 participants were significantly more likely to report good health and well-being when they spent 120 minutes or more in nature a week. The good vibe peaked at 200 to 300 minutes a week. Anything less than two hours didn’t make a difference.
There still is a lot researchers don’t know, like how physiologically nature influences health. They are racing to find answers by scanning brains, quizzing people to see how cognition is affected by different environments and planting a full-grown forest in a schoolyard to learn how much and what type of tree canopy is needed to curb air pollution and alleviate asthma.
Pediatricians at the UCSF Benioff Children’s Hospital in Oakland, Calif., have been so concerned about the lack of nature in their urban patients’ lives that they write prescriptions for it. Every year, “we ask: Do they have access to outdoors and green spaces? If no, they automatically get a referral to our program,” says Nooshin Razani. One Saturday a month “we invite them to nature outings with us,” she says. In clinical trials, Dr. Razani found that every park visit decreased parents’ stress and increased children’s resilience.
Kaiser Permanente and retailer REI are plugging forest bathing. Engineers are quantifying the health benefits of green space using satellite temperature maps, geographic mapping systems, pollution and census data and even Lidar, the remote sensing technology in self-driving cars.
NatureQuant has devised a tool that scores locations—down to the residential address—from “Nature Deficient” to “Nature Rich” based on surrounding natural elements that correlate with good health.
Many people know intuitively that nature is good for you—but still don’t spend that much time in it. The average adult spent 11 and a half hours a day consuming media in 2019, according to Nielsen. In 2019, half of 18- to 29-year-olds surveyed by the Pew Research Center said they were online almost constantly. A 2017 survey for the federal wildlife and park agencies found it “increasingly normal to spend little time outside.”
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Gretchen Daily, at Stanford, thought it would take “a really immersive experience” in nature to produce a significant benefit. As research, she assigned 45-minute walks to each of two groups. One group walked through the hills, the other down a busy, but still tree-lined thoroughfare. “I was shocked,” she says. On a series of cognitive tests afterward, “there was a massive difference. It’s not like they were in Yosemite or the wilderness,” she says, but the hill walkers performed dramatically better. Bottom line, she says: “A 45-minute walk in nature can make a world of difference to mood, creativity, the ability to use your working memory.”
Natural Capital Project, a global partnership she founded, is about to launch a software tool that maps the return on investment in nature, including the health benefits of green space.
Brent Bucknum, founder of the Hyphae Design Laboratory in Oakland, Calif., along with other scientists is studying the biophysics of vegetation in neighborhoods in Louisville, Ky., to test urban greening the way a new pharmaceutical would be tested. In one case, he is measuring the direct impact on residents’ health—asthma, heart disease, dementia—before and after planting 8,000 trees. Data from satellites and drones isn’t reliable enough to measure it or establish a causal relationship. The research is meticulous and “epically expensive,” he says. He, too, plans to launch a company with his findings.
“It’s great to simplify things for people but we see the problem as a much more complex web of components,” he says. Very small environmental fluctuations from one backyard to another can result in big differences to the health of people who live there. Such rigorous research takes time, though. Now there is more public interest in nature and health than scientists can keep up with, he says, and “I think we should leverage that.”
Write to Betsy Morris at [email protected]
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