Healthcare (Commonwealth Union) – Trees are essential to human health and well-being. They provide numerous benefits that directly impact our physical, mental, and emotional health. From purifying the air, we breathe to reducing stress levels, trees play a vital role in creating a healthy environment for us to thrive in.
The University of Louisville, innovative Green Heart Louisville Project has discovered that residents in neighborhoods where the quantity of trees and shrubs was more than doubled experienced lower levels of an inflammation-related blood marker compared to those in areas without the additional greenery. This type of inflammation is a significant risk factor for heart disease and other chronic conditions.
Launched in 2018 by the Christina Lee Brown Envirome Institute, in collaboration with The Nature Conservancy, Washington University in St. Louis, Hyphae Design Laboratory, and other partners, this pioneering project aims to determine whether living in greener environments enhances heart health. The study’s design closely parallels clinical trials that evaluate the effectiveness of medical treatments. The research team introduced numerous large trees and shrubs to some neighborhoods while leaving others unchanged, then analyzed the health data of residents to assess the impact of increased greenery on their well-being.
“The Green Heart Louisville Project is an excellent example of how our university’s innovative and collaborative researchers are working to improve lives in our community and far beyond,” says UofL President Kim Schatzel. “Trees are beautiful, but these results show that the trees around us are also beneficial to individual and community health. Through this and many other projects, the Envirome Institute is improving health at the community level, not just for individuals, but for everyone living in a neighborhood.”
For the evaluation purposes of the health status of the community at the study’s outset, researchers collected blood, urine, hair, and nail samples, and recorded health data from 745 residents in a four-square-mile area of southern Louisville. They also gathered detailed information on tree coverage and air pollution levels in the region.
After this initial data was collected, the Envirome Institute collaborated with The Nature Conservancy and various local partners and contractors to plant over 8,000 large trees and shrubs in selected neighborhoods within the project area. The residents of the areas that received the plantings were considered the treated group, and their health outcomes were compared to those of nearby neighborhoods where no new trees were planted.
Following the planting, the research team re-evaluated the health of the residents. They discovered that those living in the greened areas had 13-20 percentage lower levels of a biomarker for general inflammation, known as high-sensitivity C-reactive protein (hsCRP), compared to those in areas without new plantings. Elevated hsCRP levels are closely linked to an increased risk of cardiovascular disease and are an even stronger predictor of heart attacks than cholesterol levels. Higher CRP levels also indicate a greater risk of diabetes and certain cancers.
A reduction in hsCRP by this percentage translates to an estimated 10-15 percentage decrease in the risk of heart attacks, cancer, or death from any disease.
Aruni Bhatnagar, director of the Envirome Institute and a professor of medicine at UofL, shared that the findings from the Green Heart Louisville Project reveal that trees offer more than just aesthetic value and shade—they can enhance the health of nearby residents. He indicated that while research on prior occasions has linked living in green areas to better health, this is the first study to demonstrate that intentionally increasing greenery in a neighborhood can lead to improved health outcomes. Bhatnagar further indicated that with these results and more studies on the way, they are getting closer to understanding how local tree cover impacts the well-being of residents and this discovery will strengthen efforts to expand urban greenspaces.
