Green Heart Louisville Project
This groundbreaking project is a clinical trial where trees are the medicine.
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What is the Green Heart Louisville Project?
With a multimillion-dollar investment in underserved neighborhoods in South Louisville, the Green Heart Project seeks to demonstrate the scientific link between nature and human health.
By tackling two critical problems – air pollution and chronic disease – with a new, nature-based approach, Green Heart hopes to create a platform for major change. What we learn in Louisville could improve the lives of thousands of people here in our city and potentially millions of people worldwide.
Project Goals
While there is a growing body of scientific observations linking environmental health to the wellbeing of people, especially in urban areas, the Green Heart Louisville Project is examining, for the first time, if increasing greenness in an urban community reduces the levels of air pollution in the neighborhood, decreases the risk of chronic disease and increases outdoor activity and relationships between neighbors.
Green Heart Will Help Us Discover
- How to plant trees in urban communities to maximize the removal of air pollution
- If increasing green space affects the risks of developing obesity, diabetes and heart disease
- If increasing urban green space reduces mental stress, enhances social cohesion and increases physical activity
- If urban green space affects crime rates, property values, storm water runoff, energy use and heat island effect.
HEAL Study
The Health, Environment, and Action in Louisville (HEAL) Study measures the health of hundreds of people living in the Green Heart study area. We acquired baseline health and psychometric data from study participants, including vascular and respiratory health as well as self-reported mood and lifestyle information. The same data has been collected from study participants on a regular basis after we added thousands of trees and shrubs to their neighborhoods. We are also measuring exposure to air pollution and other inhaled compounds. The data collected have allowed us to get our first real look at the effects of increased greenness on health. We expect to see larger impacts once the trees mature and have had a longer amount of time to impart benefits to nearby residents.
First Clinical Outcomes
In August of 2024, the Green Heart Louisville team announced the first clinical outcomes from the study. Initial findings indicate that people living in neighborhoods where the number of trees and shrubs was more than doubled showed lower levels of a blood marker of inflammation than those living in the control area. General inflammation is an important risk indicator for heart disease and other chronic diseases.
Those living in the greened area had 13-20% lower levels of a biomarker of general inflammation, a measure called high-sensitivity C-reactive protein (hsCRP), compared to those living in the areas that did not receive any new trees or shrubs. Higher levels of hsCRP are strongly associated with a risk of cardiovascular disease and are an even stronger indicator of heart attack risk than cholesterol levels. Higher CRP levels also indicate a higher risk of diabetes and certain cancers.
FY25 Project Snapshot
Community meetings
Peer-reviewed research papers
Enrolled health study participants
Tree Planting & Maintenance
Large-scale tree and shrub planting was completed in June 2022, with thousands of new plants and trees placed across the study area. Green Heart Project trees are strategically placed to reduce air pollution in areas surrounding homes, businesses and roadways, including the Watterson Expressway (I-264), which cuts through the center of the study area.
The Green Heart Project Receives National Acclaim
The Green Heart Louisville Project continues to receive national attention. PBS NewsHour heralded the project’s launch in 2019. The project was presented at multiple international conferences including the International Urban Forestry Conference in Washington DC in 2023 as well as at the annual conference of Keep America Beautiful in San Diego in February 2024. The project received extraordinary coverage in The Washington Post (login required) in early 2024 as one of the most remarkable health/science projects in the country. The announcement of the first clinical results was covered by many news outlets including the TODAY Show.
Visit the Green Heart Project Website
Learn more about the Green Heart Louisville Project and see how you can participate.