SAN FRANCISCO (KGO) -- Drive through almost any part the Bay Area, and you'll eventually pass from tree-lined streets to grittier cement-heavy neighborhoods with far less tree canopy. A so called green divide that's often visible in lower income areas with a higher percentage of people of color. But now, a new study is suggesting the consequences could also be a measurable health risk.
"What we found was that even once you account for the sort of demographic differences in in between low income and disadvantaged communities, and to more white and high income communities, there was still a relationship between nature and COVID outcomes," says Erica Spotswood, Ph.D., of the San Francisco Estuary Institute.
Spotswood is a lead scientist at the institute. Along with colleague Rob McDonald of The Nature Conservancy, she compared data from 17 states that track COVID infections by zip code. They found that statistically neighborhoods with predominantly people of color typically had both less access to green space and higher infection rates. But to better understand the link, the team then adjusted the numbers to account for variables like race, income and population density. They found that even a modest increase of greening correlated with a 4% lower COVID rate in statistical models.
"So that's like saying, two neighborhoods that are sort of equal in every other way, except for the difference in greenness, the ones with more green had less COVID. So that's a pretty surprising finding," says Spotswood.
Some have theorized that availability of green space might lead people to separate more, or perhaps contribute to healthier populations in general. Whatever the driver, researchers believe the difference can now be viewed as both a health and social justice issue.
While It can be easy to spot the difference in tree cover as you pass through different neighborhood. But it can be harder to spot the invisible borders that explain the reason for it. For that you have to drive back in time.
"There absolutely is a history of redlining and blockbusting in this area. And that occurred, you know, during the same time period, as a lot of these big infrastructure projects were being put in place," points out urban forester Uriel Hernandez.
Hernandez has worked to increase tree density in Bay Area cities where banks may have been historically hesitant to write single-family mortgages, or where local governments were strapped for cash. It's a greening effort that's taken broad initiatives.
"So really having that strategic thinking in mind, not doing it piecemeal. Doing it piecemeal, is really how we got into this situation with all these neighborhoods being so distinct and different, and things kind of being overlooked," says Hernandez.
And back at the San Francisco Estuary Institute, researchers are hoping that framing the green divide as an significant health issue, will help convince cities and countries to devote more resources to repairing it.
"Because it touches us in a way that, you know, maybe people don't care as much about the birds that can be supported by the trees outside your house. But if you know how closely connected, those trees are to your human health, you may be more incentivized to take action," Spotswood argues.
And perhaps, begin to right an historical wrong, in the midst of an historical crisis.
Click on the links before for more insight into the study: