Among the authors for this work were researchers from the , Louisville Metro Department of Public Health and Wellness, Louisville Metro Office of Civic Innovation and Technology, Family Allergy & Asthma, Columbia University Mailman School of Public Health, Propeller Health, University of California Berkeley, Harvard TH Chan School of Public Health, University of Texas at Austin and Colorado State University.

Coal-fired power plants are known to emit pollutants associated with adverse health effects, including increased asthma attacks, asthma-related ED visits and hospitalizations. In 2014, coal-fired power plants accounted for 63 percent of economy-wide emissions of sulfur dioxide (SO₂) in the United States. Historically, Kentucky has ranked among the top five states in the U.S. for emissions from power generation.

Starting with a pilot in 2012, the city of Louisville embarked on a project called , which aimed to use data from digital inhaler sensors to gain insights into the impact of local air quality on the burden of respiratory disease in the community. More than 1,200 Louisville residents with asthma and COPD were equipped with sensors produced by , which attach to patients’ existing inhalers and deliver insights on medication use, symptoms and environmental factors to an app on their smartphone.

Between 2013 and 2016, one coal-fired power plant in the Louisville area retired coal as an energy source and three others installed stricter emission controls to comply with regulations from the U.S. Environmental Protection Agency. Researchers took advantage of these circumstances to analyze the impact of the coal-fired power plant energy transitions on residents’ respiratory health, using data from Propeller and local hospitals to assess how asthma-related symptoms, ED visits and hospitalizations changed over time.

The study looked at the frequency of the total number of asthma-related ED visits and hospitalizations per ZIP code in Jefferson County, where Louisville is located, as well as the frequency of asthma rescue medication use among 207 people. Data on rescue medication use for asthma was used as a proxy for patients’ symptoms, as patients use their rescue medication for acute relief from symptoms such as coughing and shortness of breath.

Ted Smith, PhD, director of the Center for Healthy Air, Water and Soil in the UofL Envirome Institute and co-author of the study, said the work confirms important connections between environment and health.

“At the Envirome Institute and the , we are pioneering an approach that puts a focus on place in medicine – the places where people live and how their location affects clinical outcomes,” Smith said. “This research is a great example of the impact of environmental factors on people’s health. Air pollution first affects the lungs, but we know that when people breathe pollutants, it also affects other organs, including the heart.”

The study spanned 2012 to 2017, when four coal-fired power plants in Jefferson County either retired coal or installed stricter SO₂ controls. The researchers found that energy transitions in the spring of 2015 resulted in three fewer hospitalizations and ED visits per ZIP code per quarter in the following year, when comparing areas that had high coal-fired power plant emission exposure prior to the transition to those with lower levels. This translates into nearly 400 avoided hospitalizations and ED visits each year across Jefferson County.

At the individual level, the Mill Creek SO₂ scrubber installed in June 2016 was associated with a 17-percent immediate reduction in rescue medication use, which was maintained thereafter. The study also found the odds of having high rescue use throughout a month (on average more than four puffs per day) was reduced by 32 percent following the June 2016 energy transition.

“AIR Louisville brought together local government, public and private partners and residents for a common mission: To leverage local data to help push for safer and healthier air,” said Louisville Mayor Greg Fischer. “This study demonstrates the public health impact of retiring coal as an energy source or further controlling coal-fired emissions.”

“This study was unique in its ability to measure asthma morbidity based on both hospitalizations and daily symptoms, and to leverage an abrupt change in environmental exposure to more directly attribute changes in asthma exacerbation to changes in coal-fired power plant emissions,” said Joan Casey, PhD, lead author of the paper and assistant professor of environmental health sciences at Columbia University Mailman School of Public Health.

The main funding for the project was provided by the Robert Wood Johnson Foundation. Support also was provided by the Foundation for a Healthy Kentucky, Norton Healthcare Foundation, Owsley Brown Charitable Foundation, the American Lung Association, the National Institute of Environmental Health Sciences and the U.S. Environmental Protection Agency. The contents of the research and related materials are solely the responsibility of the grantee and do not necessarily represent the official views of the USEPA or the Robert Wood Johnson Foundation.

In this study, the first of its kind, researchers from the University of Louisville investigated the impact of neighborhood greenspaces on individual-level markers of stress and cardiovascular disease risk.

Over five years, blood and urine samples were collected from 408 people of varying ages, ethnicities and socioeconomic levels, then assessed for biomarkers of blood vessel injury and the risk of having cardiovascular disease. The participants were recruited from the and were largely at elevated risk for developing cardiovascular diseases.

The density of the greenspaces near the participants’ residences were measured using the Normalized Difference Vegetation Index (NDVI), a tool that indicates levels of vegetation density created from satellite imagery collected by NASA and USGS. Air pollution levels also were assessed using particulate matter from the EPA and roadway exposure measurements.

Researchers found living in areas with more green vegetation was associated with:

• Lower urinary levels of epinephrine, indicating lower levels of stress;
• Lower urinary levels of F2-isoprostane, indicating better health (less oxidative stress);
• Higher capacity to repair blood vessels.

They also found that associations with epinephrine were stronger among women, study participants not taking beta-blockers – which reduce the heart’s workload and lower blood pressure – and people who had not previously had a heart attack.

“Our study shows that living in a neighborhood dense with trees, bushes and other green vegetation may be good for the health of your heart and blood vessels,” said Aruni Bhatnagar, PhD, lead study author and professor of medicine and director of the UofL and the . “Indeed, increasing the amount of vegetation in a neighborhood may be an unrecognized environmental influence on cardiovascular health and a potentially significant public health intervention.”

The findings were independent of age, sex, ethnicity, smoking status, neighborhood deprivation, use of statin medications and roadway exposure.

Previous studies also have suggested that neighborhood greenspaces are associated with positive effects on overall physical and psychosocial health and well-being, as well as reduced rates of death from cardiovascular and respiratory diseases and improved rates of stroke survival, according to Bhatnagar. However, these reports are largely limited by their reliance on self-reported questionnaires and area-level records and evaluations, Bhatnagar said.

Co-authors of this study are Ray Yeager, Ph.D.; Daniel W. Riggs, M.S.; Natasha DeJarnett, Ph.D.; David J. Tollerud, Ph.D.; Jeffrey Wilson, Ph.D.; Daniel J. Conklin, Ph.D.; Timothy E. O’Toole, Ph.D.; James McCracken, Ph.D.; Pawel Lorkiewicz, Ph.D.; Xie Zhengzhi, Ph.D.; Nagma Zafar, M.D., Ph.D.; Sathya S. Krishnasamy, M.D.; Sanjay Srivastava, Ph.D.; Jordan Finch, M.S.; Rachel J. Keith, Ph.D.; Andrew DeFilippis, M.D.;  Shesh N. Rai, Ph.D. and Gilbert Liu, M.D. Author disclosures are on the manuscript.

The WellPoint Foundation and the National Institute of Environmental Health Sciences of the National Institutes of Health supported the study. View the manuscript .