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.”
BY MARK
WILSON 11.25.19
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.
