Reduce coal-fired power plant emissions, improve respiratory health

Kicking coal completely or scrubbing health-harming sulfur dioxide out of the air reduces serious asthma-related hospitalization and emergency room visits and inhaler use among asthmatics.

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Like most postdocs, I did not have large research funds. In 2018, I led a paper that found shuttering oil and coal-fired power plants in California may have reduced preterm birth in nearby communities. This was exciting. I had designed the study, applied for a small grant (30,000 USD), and had (just) 2,000 USD to pay a research assistant. Given these financial constraints, we used a simple metric of exposure and compared pregnant women living within 5-km (most exposed) to those living within 10 to 20-km (least exposed) of power plants. This design had several issues: are all women within 5-km equally exposed? No. Does wind direction and weather matter? Yes. Should we have incorporated changes in actual emissions from each power plant? Absolutely. At the time, however, our team lacked this expertise. I had to wait for a LinkedIn-type connection to improve upon my original design.

Later in 2018, I received an email from my co-author, Betsy Ogburn, and–great news!–her colleague Cory Zigler had read our paper and wanted to talk about his new exposure metric. The metric, HyADS, tracks movement and transformation of coal-fired power plant emissions through the atmosphere. I chatted with Cory and Lucas Henneman on BlueJeans–an ironic name for videoconferencing software as pajamas are the more common choice–and we decided to explore how HyADS could improve an ongoing study that I had with Propeller Health’s Meredith Barrett.

At a retirement party, Meredith had described to me Propeller’s Air Louisville program, which supplied digital medication sensors to Louisville, Kentucky residents with asthma, which allowed Propeller to track the location and time of participants’ rescue inhaler use. I immediately thought about Kentucky’s coal electricity generation and found that the state was the #3 producer of coal-generated electricity in the U.S. in 2018, with steep declines from 2013–2017.

Kentucky was the #2 or #3 producer of electricity from coal in the U.S. from 2001-2019

Together, we decided to test whether coal-fired power plant retirements or SO2 scrubbers (which dramatically cut SO2 emissions) improved asthma outcomes in Louisville. Our findings were published in Nature Energy.

HyADS told us which coal-fired power plants most affected 2012 air quality in Louisville. Out of 478 operating coal-fired power plants in 2012, Mill Creek and Clifty Creek, located to the west and east of Louisville, respectively, were the top contributors to poor air quality.

The four coal-fired power plants that most affected air quality in Louisville, KY in 2012. Figure by Lucas Henneman.

We then used triangulation to combine different datasets and analytic strategies to answer the same question. We found that (1) retirements and scrubbers reduced Louisville emissions exposures; (2) emissions reductions resulted in 400 prevented asthma-related hospitalizations and emergency room visits; and (3) a 2016 SO2 scrubber installation appeared to reduce rescue inhaler use by 17% among Air Louisville participants. These three results converged, increasing our confidence that closing or controlling emissions at coal-fired power plants reduced exposure and improved asthma outcomes.

Research triangulation
Three results converged to suggest retiring and retrofitting coal-fired power plants benefits health

Our results come as the U.S. EPA has suspended enforcement of environmental laws during the COVID-19 pandemic. The U.S. has stark environmental inequities, with poorer communities and communities of color facing a disproportionate burden of air pollution as well as elevated rates of asthma and other respiratory diseases. Members of these communities appear at greatest risk of COVID-19 infection and death. In a time of need the U.S. EPA has stopped protecting those who need it most.


Read the Nature Energy paper here.
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Joan Casey

Assistant Professor, Columbia University Mailman School of Public Health

Environmental epidemiologist studying emerging environmental exposures, with a focus on sustainability and social determinants of health.

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