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Deaths associated with pollution from coal power plants

From NIH Research matters

Coal-burning power plants are a major source of fine particulate matter (PM2.5) air pollution. Exposure to PM2.5 is associated with increased risk of death. To judge the success of measures to improve air quality, we need to estimate the health impacts, including death, associated with specific air pollution sources. Previous attempts to do so have assumed that PM2.5 from all sources is equally toxic. But coal PM2.5 is rich in sulfur dioxide, black carbon, and metals. Recent evidence suggests that such emissions may be more deadly than PM2.5 from other sources.

Seven factory chimneys belching smoke as the sun sets or rises

A team of researchers led by Dr. Lucas Henneman at George Mason University, the Harvard School of Public Health, and the University of Texas at Austin set out to estimate the number of deaths nationwide associated with PM2.5 from coal power plants. They analyzed a vast dataset of Medicare death records dating from 1999. They then modeled where air currents carried emissions from 480 individual coal power plants. This allowed them to estimate coal PM2.5 exposure where the people lived and died. Results appeared in Science on Nov. 23, 2023.

The researchers calculated that for every 1 μg/m3 increase in coal PM2.5, mortality increased by 1.12%. This is more than twice the risk that was previously associated with general PM2.5 exposure from all air pollution sources. The team estimated that between 1999 and 2020, 460,000 deaths would not have occurred in the absence of emission from the coal power plants.

There was a notable decline in the number of deaths from coal PM2.5 during the period studied. From 2000 to 2008, deaths associated with coal PM2.5 were 25% of all PM2.5-related deaths in the Medicare population. From 2013 to 2016, coal PM2.5 deaths were only 7% of all PM2.5-related deaths. This was likely due to coal power plant retirements and air pollution regulations that reduced emissions.

About 140 coal power plants were each associated with more than 1,000 excess deaths during the study period. Ten plants, all located east of the Mississippi River, were associated with more than 5,000 deaths. When a plant installed pollution control technology (called emissions scrubbers) or shut down, the number of associated deaths declined. For example, the Keystone facility in Pennsylvania was one of the deadliest power plants over the period studied. It was associated with more than 600 deaths per year on average before installing emissions scrubbers. After scrubber installation, that number dropped to 80 per year.

“PM2.5 from coal has been treated as if it’s just another air pollutant. But it’s much more harmful than we thought, and its mortality burden has been seriously underestimated,” Henneman explains.

But the decline in mortality over time highlights the success of emissions reductions at improving health. “I see this as a success story,” says senior author Dr. Corwin Zigler of the University of Texas at Austin. “Coal power plants were this major burden that U.S. policies have already significantly reduced.”

This approach to pinpoint the effects of individual power plants might be used to design more targeted policies to further reduce the health impacts of air pollution sources.

— by Brian Doctrow, Ph.D.

Funding: NIH’s National Institute of Environmental Health Sciences (NIEHS), National Institute on Minority Health and Health Disparities (NIMHD), and NIA; US Environmental Protection Agency; Alfred P. Sloan Foundation; and the Health Effects Institute.

This research was supported in part by NIA grants 1RF1AG080948 and 1R01AG066793.

Reference: Henneman L, et al, Mortality risk from United States coal electricity generation. Science. 2023;382(6673):941-946. doi: 10.1126/science.adf4915.

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