In the early stages of the COVID-19 pandemic, statistics emerged showing significant discrepancies in mortality by county.

Shinsuke Tanaka, assistant professor and director of graduate studies in the Department of Agricultural and Resource Economics, wanted to use his expertise in environmental and health economics to help understand what was at the root of this puzzle.

“I wanted to understand what could explain that spatial heterogeneity of Covid’s impacts,” Tanaka says.

Tanaka published a paper in the Journal of Environmental Economics and Management showing that counties with more days of downwind pollution from power plants had higher COVID-19 mortality rates. This impact was more pronounced in under-resourced communities.

When Tanaka began his research during the 2020 lockdown, there had been a few studies looking at the links between short-term (daily or monthly) exposure to air pollution and COVID-19 mortality. But very few had considered the impacts of long-term air pollution exposure.

Tanaka looked at the impacts of air pollution on counties within 20 miles of fossil-fueled power plants. He determined this was an appropriate radius based on readings from EPA air pollution monitors showing that air pollutants travelled downwind about that far before dissipating.

Then, Tanaka calculated what percentage of days in a 10-year period before the pandemic a given county in the contiguous U.S. was downwind of power plant pollution.

“That gives me a measure of long-term exposure to pollution for each county before Covid started,” Tanaka says.

Tanaka found that counties with an average downwind frequency of 13.5% had 28% more COVID-19 deaths within the first week of April 2020 compared to upwind counties the same distance from a plant.

Tanaka extended his research until the third mortality peak in January 2021. He found the cumulative mortality rate was 45% higher for communities that were more frequently downwind.

Tanaka’s findings also demonstrated that these impacts were greater in counties with higher poverty rates, lower health insurance coverage, and lower education levels.

“That indicates that disadvantaged communities and counties faced even greater burdens of pollution from these power plants during the pandemic,” Tanaka says.

Such underlying disparities mean people in these communities are more likely to have underlying health conditions and less access to health care when they get sick.

Other studies on links between air pollution and health have struggled to separate air pollution from other potentially confounding variables. By focusing on downwind patterns, an essentially random natural event, Tanaka was able to isolate air pollution as a variable.

“This method allowed me to isolate the impact of pollution exposure more effectively,” Tanaka says.

By demonstrating a method that can successfully isolate long-term air pollution exposure from confounding variables, Tanaka’s study paves the way for more research on other health outcomes.

“COVID-19 is, of course, a very specific mortality, and I expect to see more studies on the impact of long-term air pollution exposure on various other health outcomes.”

Research such as Tanaka’s demonstrates that the significant public health costs of fossil fuels will remain critical to public policy discussions.

“It will be very important to understand which power plants are having greater impacts, and what plants should be closed,” Tanaka says. “Those discussions should continue.”

This work relates to CAHNR’s Strategic Vision area focused on  Enhancing Health and Well-Being Locally, Nationally, and Globally.

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