More trees, fewer health problems: Inside Green Heart Louisville’s five year study on air pollution control

If you live in Louisville long enough, one popular jab you might hear is how poor the air quality is. Although it’s easy to forget about something you can’t always see, air pollution can harm everyone and contributes to a number of diseases.

Green Heart Louisville, a five-year project through UofL, is attempting to be a part of the solution, as it plans to plant approximately 8,000 trees in South Louisville neighborhoods and study their health effects on residents. Planting began Oct. 5 with the help of Louisville Grows, a nonprofit organization, which is canvassing and coordinating the planting of various trees and shrubs on private residential property.

“This is sort of a very unique way of looking at nature and how we relate to nature within our urban environments,” said Dr. Aruni Bhatnagar, director of UofL’s Envirome Institute, which is spearheading the project. “And by understanding this link, we might be able to provide a way forward — not only for places in Louisville, but cities around the world.”

Consider this: According to the State of the Air 2019 report from the American Lung Association, Jefferson County received an “F” grade for high ozone days from 2015-2017. For high particle pollution days, they received a “B” grade. “Both ozone and particle pollution are dangerous to public health and increase the risk of premature death and other serious health effects like lung cancer, asthma attacks, cardiovascular damage and so forth,” Shannon Baker, advocacy director for the American Lung Association in Kentucky, said.

Trees are capable of removing significant amounts of air pollution from cities, so losing them can harm your health — both physical and mental. But between 2004 and 2012, Louisville lost about 54,000 trees per year, according to the city’s 2015 Urban Tree Canopy Assessment. In Louisville, the declining tree canopy also contributed to the formation of an urban heat island, a phenomenon where a city’s core has a hotter temperature than its edges.

Green Heart covers six communities in South Louisville, including Oakdale, Wilder Park, Taylor-Berry, Beechmont, Jacobs and Hazelwood. According to Bhatnagar, these neighborhoods were selected because they are middle income and racially diverse, and also because they are near the Watterson Expressway, which would give Green Heart the opportunity to measure how the residents are impacted by exposure to the freeway.

Through a study that Green Heart is calling the Health Environment and Action in Louisville (HEAL), it is monitoring the blood pressure, cholesterol, liver function and heavy metal levels — among other vital numbers — of about 730 residents and will collect further data in 2021, after greening the area.

The researchers are also measuring a number of different ways in which the addition of trees could possibly affect the area, including stress, physical activity, depression, wellbeing and even biodiversity — for which they collected data on butterflies, insects and bats in the area.

“There’s a lot of different reasons why greening may affect someone and we have to understand all those on a certain level to be able to figure out what role air pollution plays or what role physical activity plays,” said Dr. Rachel Keith, leader of the HEAL study.

The Green Heart project grew from a smaller project called Green For Good that occurred from 2015 to 2017, during which time the Envirome Institute investigated how planting trees at St. Margaret Mary Catholic Elementary School would impact the health of 60 students and 24 adults. They chose St. Margaret’s due to the nearby freeway, a cause of air pollution at the school.


Keith said Green For Good showed the subjects’ improvement in immune cells and other cells that represent vascular and heart health. The final study of Green For Good also found that the particulate pollution was 60% lower behind the biofilter created by the trees.

“That gave us, I think, a good jumping off bar to say, ‘We can create good, validated, vegetative buffers that could change these dynamics of air pollution and we’re seeing health differences,’” Keith said. “So why don’t we look at a larger population and explore that a little bit more in a bigger setting?”

The Green Heart project receives funding from The Nature Conservancy and the National Institutes for Health and is also partnered with Hyphae Design Lab and The Institute for Healthy Air, Water and Soil, among many other organizations. Despite its many collaborators, Green Heart wants the neighborhood itself to be certain of its important role in the project.

“I think the neighborhood in general is also looking for a way to be recognized and do something good for the community,” Keith said. “That’s been a big feedback on all levels throughout the community, that they’ve always viewed themselves as a very vibrant, rich history. And they want to have that come back again, except there can be a lot of negative press popping up about the area, and they want to overcome that.”

Green Heart held a kickoff event Oct. 14, during which Metro Councilwoman Keisha Dorsey expressed excitement for the community’s action and participation in the project.

“We have innovative minds in this community that are pushing the envelope, that are going beyond the logical and the theoretical,” Dorsey said. “I think we know that if we plant more trees, that there’s a positive impact. But what we see in this community are people pushing the envelope to make that a data-based, political, policy-based decision.”

Community members Kimberly Werner and Tommy Hensley showed their dedication to the project by having the event take place on their lawn, which concluded with Green Heart planting a tree in their front yard. The couple said they’re excited about the project and think the trees are “just gorgeous.”

“I just couldn’t imagine the world without trees,” Hensley said. “It would just be nothing.”

David Phemister, state director for The Nature Conservancy in Kentucky, said looking ahead, he hopes to see strong evidence from the study proving nature-based solutions to be effective and healthy for the community.

“We really hope for a Louisville in the future in the same as what we hope for Kentucky, or the U.S. or the planet — a future where people and nature thrive together,” Phemister said.