Contact with nature has a host of potential physical and psychological benefits, according to a growing body of evidence. Researchers have focused mostly on the health effects of spending time in parks or wilderness, but two recent studies suggest there are potential benefits of living in leafy, green neighborhoods or even near leafy, green blocks in inner cities.
In a study in the Journal of the American Heart Association in December 2018, researchers from the University of Louisville, Kentucky, assessed the impact that neighborhood green spaces had on stress and cardiovascular disease risk in local residents. They collected blood and urine samples from 408 people who were recruited from the university’s preventive cardiology clinic and were at elevated cardiovascular risk.
They then correlated biomarkers of cardiovascular risk in the participants’ blood or urine with the density of green spaces near their home. Green space was measured using a tool that gauges vegetationdensity from satellite photos.
The researchers found that living in areas with more vegetation was associated with lower urinary levels of the hormone epinephrine (indicating lower levels of psychological stress) and positive effects on other markers of cardiovascular health. The associations were stronger in women than in men, but were independent of age, ethnicity, smoking status, neighborhood wealth, use of statins, and roadway pollution exposure.
“Increasing the amount of vegetation in a neighborhood may be an unrecognized environmental influence on cardiovascular health and a potentially significant public health intervention,” the lead author stated.
The other study, in JAMA Network Open in July 2018,suggested that just “greening” vacant lots in a city can improve the mental health of nearby residents. For 18 months, researchers followed 342 residents of 110 clusters of blocks (mostly lower-income) in Philadelphia, which contained a total of 541 vacant lots. One-third of the residents lived near empty lots that were turned green with grass and trees; one-third lived near lots that had trash cleanup but no greening; and one-third (control group) continued to live near vacant lots that had nothing done to them.
After vacant lots were turned green, nearby residents reported a 40 percent reduction in feeling depressed and a 50 percent reduction in feeling worthless, compared to the control group. Those living near lots that were merely cleaned up had no significant changes in self-reported mental health.
The researchers suggested that replacing empty lots with green spaces can not only reduce depression, stress, and mental fatigue, but also improve social cohesion and interaction and feelings of safety. “Making structural changes to the lowest-resource neighborhoods can make them healthier and may be an important mechanism to address persistent and entrenched socioeconomic health disparities,” they concluded.