Asthma hospitalizations dropped after Louisville power plants retired coal or installed better emission controls

LOUISVILLE, Ky. – After four Louisville coal-fired power plants either retired coal as their energy source or installed stricter emissions controls, local residents’ asthma symptoms and asthma-related hospitalizations and emergency department (ED) visits dropped dramatically, according to research published in Nature Energy this week. Among the authors for this work were researchers from the University of Louisville Christina Lee Brown Envirome Institute, 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 AIR Louisville, 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 Propeller Health, 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, Ph.D., 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 UofL Division of Environmental Medicine, 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, Ph.D., 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.

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