The Green Heart Study at the University of Louisiana involved health monitoring of 745 Louisville residents.
A more robust tree canopy can reduce inflammation among residents of a residential area, new research from the University of Louisville shows.
The Green Heart study, conducted by the university’s Christina Lee Brown Environmental Institute, involved planting more than 8,000 trees and shrubs in south Louisville and ongoing health monitoring of 745 participants from the region.
The researchers found that levels of high-sensitivity C-reactive protein – an important biological marker of inflammation – were 13 percent lower in residents whose neighborhoods had thousands of trees and shrubs planted than in residents whose neighborhoods were not greened.
Inflammation is a risk indicator for heart disease and other chronic conditions. Recent health equity data show that heart disease was the leading cause of death in Louisville from 2017 to 2021.
The lower levels of C-reactive protein observed by researchers may help estimate residents’ risk of heart attack – possibly by 10 to 15%, Aruni Bhatnagar, director of the Envirome Institute, said Tuesday.
“Just think about it: not only the human toll of heart attacks and chronic diseases,” Bhatnagar said, “but also the economic impact of this work.”
The results of the project, he added in a statement, “will reinforce the push to increase urban green spaces” and could potentially be replicated in other municipalities across the country.
Further evidence of the benefits of trees
Green Heart’s findings add to a wealth of scientific evidence on how trees can promote the health, well-being and economic prosperity of a community.
Previous estimates have found that Louisville’s tree canopy saves the city an estimated $330 million each year by capturing more than 15 billion gallons of rainwater and filtering harmful pollutants from the air.
Trees also cool residential areas by providing shade and through evapotranspiration, the process by which plants release moisture into the air.
These features are becoming increasingly important as Louisville’s summers get warmer and the number of dangerously hot days increases.
The Green Heart Project’s results were announced Tuesday, amid an active air quality alert for ozone and temperatures exceeding 90 degrees.
Louisville lacks treetops
Previous surveys have shown that many Louisville neighborhoods lack sufficient tree canopy.
As the Courier Journal reported last year, gaps in tree canopy cover are most glaring in Louisville neighborhoods that most need the benefits of trees.
On average, communities with the least wealth also have the lowest tree cover, while wealthier neighborhoods have the highest tree cover.
This inequality reinforces other inequalities – such as vulnerability to extreme heat and poor air quality.
And Louisville’s building codes are vague when it comes to protecting tree canopies, allowing too many mature trees to be cut down when developing rural areas of the county, advocates say.
Authorities announced last year that Louisville received federal funding to improve tree canopies in underserved neighborhoods, supporting the planting of thousands of trees.
In addition, Metro officials are working with TreesLouisville on an “Urban Forest Master Plan” to guide the city’s strategy for preserving and enhancing tree canopies.
Connor Giffin is an environmental reporter for the Courier Journal. You can reach him directly at [email protected] or on X @byconnorgiffin.
