Fine dust from coal is more harmful than expected

Photo of a coal-fired power plant in the USA

Coal-fired power plants produce huge amounts of particulate matter that is harmful to health. © baranozdemir / iStock

It has long been known that fine dust from burning coal is harmful to health. But now data from the US suggests that these power plant emissions are even more harmful than previously thought. To do this, researchers evaluated a combination of health insurance data and emissions data from 480 coal-fired power plants in the USA. Accordingly, the sulfur-containing particulate matter emitted by power plants is responsible for more than 460,000 deaths between 1999 and 2020 alone. At the same time, the results show that measures to reduce emissions in the USA have already effectively prevented premature deaths.

Coal has traditionally been considered a cheap source of energy and continues to play an important role in electricity generation in many countries around the world. At the same time, it is already known that coal-fired power plants cause significant air pollution and thereby contribute to illness and death. Several studies have already tried to estimate how great this influence is on the health of the population. However, they assumed that particulate matter emitted by coal-fired power plants is no more or less harmful than other particulate matter with the same particle size of 2.5 micrometers (PM2.5) from other sources.

Emission fields and health data combined

“However, PM2.5 from coal is much more harmful than thought and the mortality burden caused has been significantly underestimated,” says Lucas Hennemann of George Mason University in Virginia. Together with his team, he compiled information from 480 coal-fired power plants in the USA on how much particulate matter and sulfur dioxide (SO2) they emitted week after week between 1999 and 2020, in which direction the wind carried the exhaust gases and what the precipitation conditions were.

The researchers combined this data with data from the American health insurance company Medicare, which is available to Americans over the age of 65 and records their health status. Hennemann and his team were particularly interested in the place of residence and the time of death of the insured. In addition, they included age, gender, previous illnesses and socioeconomic status in the analysis. By linking this data to the coal-fired power plants' emissions fields and the intensity of local particulate matter pollution, they were able to calculate what proportion of deaths were most likely due to air pollution.

Preventable deaths from air pollution

The result: “A total of 460,000 deaths among Americans over the age of 65 were due to PM2.5 from coal,” the team reports. According to their comparative analyses, exposure to sulfur-containing particulate matter from coal-fired power plants increased the mortality risk more than twice as much as particulate matter from other sources. The highest burden and associated mortality were found in the states in the eastern United States, as this region has a particularly high population density and has traditionally relied heavily on coal-fired power. Ten of the power plants examined there were each responsible for more than 5,000 deaths.

“But as well as showing how harmful coal pollution was, we also have good news: the number of deaths caused by coal was highest in 1999, but has fallen by around 95 percent by 2020 as coal-fired power plants have installed or shut down emissions control systems were," reports Henneman. While the average PM2.5 pollution from coal in the USA in 1999 was 2.34 micrograms per cubic meter of air, in 2020 it was only 0.07 micrograms per cubic meter. “I see this as a success story,” says co-author Corwin Zigler from Harvard University in Boston. “Coal-fired power plants were a major burden that US policy has already significantly reduced. But we haven't completely eliminated the burden. This study provides us with a better understanding of how health can continue to improve and lives can be saved as we continue to move toward a clean energy future.”

Global increase in coal-fired power generation

While the USA is increasingly reducing electricity generation from coal, experts expect that the importance of coal in the global energy mix will increase in the coming years. For example, several European countries, including Germany, are increasingly relying on coal again because the conflict between Russia and Ukraine has resulted in supplies of other fossil fuels such as oil and natural gas being eliminated or becoming significantly more expensive. “Our results can help policymakers and regulators find cost-effective solutions to clean air, for example by mandating emissions controls or encouraging utilities to use other energy sources, such as renewable energy,” said Hennemann.

Source: Lucas Hennemann (George Mason University Volgenau School of Engineering, Fairfax, Virginia, USA) et al., Science, doi: 10.1126/science.adf4915

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