The lead author of a sweeping study on the health benefits of greenery, David Rojas, advises that “where you are, increase and support more green-ness around your home.”
If you want to live longer, live around green space.
That’s the simple conclusion of the largest analysis ever performed on the relationship between the environment and human longevity—ever. Eight million people. Seven countries. One simple finding: “When you are exposed to greenery or greenness around your home, your probability to die . . . is less compared to those with less green-ness around their home,” says David Rojas, researcher at the Barcelona Institute for Global Health and Colorado State University, and lead author of the study, which was published in The Lancet Planet Health (PDF) in collaboration with the World Health Organization. Specifically, the research team found that for every 10% increase in vegetation that’s within 1,600 feet of your home, your probability of death drops by 4%.
Those hard numbers are the result of a large metastudy analyzing nine separate longitudinal studies about health and green space that looked at how and how long people lived over long periods of time. Subjects were from countries around the globe, too: Australia, Canada, China, Spain, Italy, Switzerland, and the U.S.
As Rojas explains, in every country, the finding was the same. People who lived near more green space lived longer than people who lived near less. This green space can be grass, trees, or gardens. It can be public or private space. The study didn’t discriminate, nor did it have the data fidelity to claim that some plants were better for our health than others. (Satellite imagery was used to accurately measure vegetation around homes.)
Why do people with access to more green spaces live longer? Rojas doesn’t claim to know. He posits there are several possibilities, and perhaps they are even working in concert. Just looking at plants is known to lower stress, which decreases damaging cortisol in our blood. Touching plants might impact the microbiome on our skin and strengthen our immune system. There’s also the benefit of air quality: A single tree pumps out enough oxygen for four people to breathe. Rojas even points out that greenery helps cool the urban island heat effect, making some areas of cities cooler and more comfortable than others. Plants just do a whole lot of measurable good. It’s almost as if humans evolved to be around them or something!
So what should we do with this information? “Maybe the more straightforward recommendation is not to move to where there’s more green, but where you are, increase and support more green-ness around your home,” says Rojas. “That would be the easiest thing to conclude and be the most applicable to everyone.”
Rojas suggests urban planners need to be placing low-maintenance, native plants wherever they can and stretching budgets as necessary to make that happen. “Less concrete, more green,” he says. “If you have a small space in the street you can substitute some grass for concrete . . . or any tree or plant will start to produce this change.”
He also suggests that you bring more plants into both your home and office. The study didn’t study indoor plant life, but Rojas is confident that it would make a positive impact on your well-being. (Again, there is evidence that plants are beneficial to indoor air quality, which is more atrocious than even many scientists ever realized).
Next, Rojas wants to learn how to optimize green space to boost these demonstrable health benefits. Perhaps some plants do provide more longevity than others. Maybe a single 40-foot tree planted in a sidewalk could have the same effect as a half acre of manicured lawn. Right now, we simply don’t know. And until we do, there’s a simple rule of thumb to follow: Go as green as you reasonably can. Because your life literally depends on it.