Greener Cities, Healthier Cities?
Nature has an important role to play in urban planning—and human health.
"In these unprecedented times..." We know, the phrase has become a cliché. But it's also true—these are unprecedented times, and we're all still working to fully understand what COVID-19 means for the world. As part of our effort to help make sense of these issues, we're publishing a new series of weekly perspectives from some of TNC's top scientists to share their expertise and talk about the relationship between nature and public health—and what nature can do for our communities in these, well, unprecedented times.
Next in this series: "Conservation for the 'Last-Mile,'" by Priya Shyamsundar, TNC Lead Economist
During this time of social distancing due to COVID-19, I have been stuck working and home schooling two energetic kids from a small city apartment. What has kept me sane is daily walks with my kids, out our backdoor and down a couple blocks to a little remnant patch of woods near a stream, where we can throw rocks in the water and listen to the spring birds arriving in Washington, DC.
News reports and social media feeds are full of people like me—walking or running near home, attempting to get outside while following social distancing and quarantine guidelines.
In some places, public health officials have stated that exercising outdoors or spending time in your backyard is safe, so long as you are not ill, and you keep your distance from other people. And published science suggests that time outdoors can offer measurable mental and physical health benefits.
A study that colleagues and I published in Sustainable Earth in 2018 reviewed what many other researchers have found—that living in very dense urban environments increases stress levels, but even brief interactions with the natural world can mitigate some of the negative effects of that stress.
In this time of staying home, many of us seek the release that comes from getting outside, if only for a few minutes. But you may not realize how significant this effect is—in fact, exposure to nature has even been correlated with reductions in depression, anxiety and schizophrenia.
Living near nature also has well-established physiological benefits. Access to parks and trails tends to increase residents’ physical activity, which drives a reduction in obesity and offers myriad other related health improvements. Early research is beginning to indicate that neighborhoods with more trees have reduced instances of cardiac and respiratory disease, a connection that we’re investigating further with the Green Heart Louisville project.
Tree cover also influences the urban heat island—a term that describes the effects of heat radiating off buildings and streets, making cities hotter than surrounding areas. Areas with trees can be several degrees cooler, and TNC research has found that this level of cooling has the potential to save tens of thousands of lives globally during heat waves.
Even looking at nature through a hospital window can bring benefits. One study established that surgical patients with a natural view recovered more quickly than those whose rooms overlooked a busy highway.
Teasing apart the threads of the genetic and social determinants of human health is always complex, and it would be inaccurate to say that access to nature can prevent disease, but intriguing new connections are constantly emerging as more researchers focus their investigations at the nexus of nature and health.
But it’s important to note that access to the health benefits that nature can provide is not equitably distributed. Recent TNC research indicates that in the United States, tree cover correlates to neighborhood income, even when adjusted for the population density of different communities. As the climate continues to shift, heat is a very real environmental justice concern.
I realize that nature is a relatively small factor when we consider all the of determinants of human health, but it’s a factor that can begin to address some of the inequities of our health care system. Adding nature to communities is often a cost-effective public health measure that offers additional benefits—from wildlife habitat to stormwater and flood management to natural beauty.
A century ago, city planners were adding public parks and water treatment systems to improve public health. Today, adding other forms of natural infrastructure to cities is the next step in that progression to healthier, more livable communities.