Three multicultural women plant a tree together.
Louisville Tree Planting Four organizations partner to plant 150 trees at Shawnee Park in Louisville. © The Nature Conservancy/Devan King

Stories in Kentucky

Green Heart Project

This five-year urban laboratory investigation will measure the power of greenery as a public health strategy in Louisville neighborhoods.

The Healing Power of Trees

This segment of Cool Solutions discusses the Green Heart Project, urban heat, and how trees can make cities healthier.



In the fall of 2017, The Nature Conservancy and partners launched the Green Heart Project to examine the link between neighborhood greenery and certain physical and mental ailments. This five-year, collaborative effort, led by the University of Louisville Envirome Institute, Hyphae Design Laboratory, and TNC will inform new, cutting-edge municipal decision-making processes that connect nature with health and well-being.

Aruni Bhatnagar, Ph.D., a professor and researcher with the University of Louisville School of Medicine, worked for more than two years to develop the idea and build a team around the study.

No one knows whether and to what extent neighborhood greenery affects human health and why,” Bhatnagar said. “This work will tell us exactly how to design a neighborhood that supports human health, one that might provide protection from everything from asthma to heart disease to dementia.”

Launched with an initial $5 million grant from the Owsley Brown II Family Foundation, the Green Heart Project received additional support—just one year into the study—from the National Institute of Environmental Health Sciences for the human health assessments, and from The Nature Conservancy for initial air quality monitoring. 

An infographic illustrates the benefits of city trees.
Benefits of Urban Trees Research has linked the presence of urban trees to services that benefit humans and wildlife. © The Nature Conservancy

The growing support stems from an increasing body of research highlighting a link between urban greening and health outcomes. However, the Green Heart Project is the first controlled experiment to test urban greening in the same way a new pharmaceutical intervention would be tested. Specifically, the research team will first assess the risk of diabetes and heart disease, stress levels and the strength of social ties in 700 participants from targeted Louisville neighborhoods. The team will take baseline measurements of air pollution levels at the same time.

Next, the team will plant as many as 8,000 trees, plants and shrubs throughout the neighborhoods to create an urban ecosystem that promotes physical activity while decreasing noise, stress and air pollution. After that, the 700 participants will receive annual check-ups to evaluate how the increasing greenery has affected their physical and mental health, and their social ties.

“The project brings together the expertise of university researchers, city officials and nonprofit leaders to, for the first time, scientifically quantify a link between how humans and nature are intrinsically linked.” says David Phemister, The Nature Conservancy’s Kentucky state director. “New evidence revealed through the study will inform better policies and investments in nature, and in human health, in the future.”

In addition to Hyphae Design Laboratory and TNC, the University of Louisville Envirome Institute is collaborating on the Green Heart Project with additional partners that include Washington University in St. Louis, Cornell University and the U.S. Forest Service.