Mortality burden of air pollution from coal-burning power plants has been underestimated

Between 1999 and 2020, more than 460,000 deaths in the United States were attributable to exposure to air pollution emissions from coal-burning power plants, according to the longest-term national study of its kind. While the findings highlight the increased mortality risks from coal electricity generation, they also underscore the effectiveness of emission-reduction policies in preventing excess death. Exposure to air pollution is associated with poor health and an increased risk of death. Coal-burning electricity-generating units (EGUs), also known as power plants, are a major contributor to poor air quality. Although coal EGU air pollution emissions have declined in the U.S. in recent decades, global coal use for electricity generation is projected to increase. Recent studies have suggested that exposure to fine particulate matter (PM_2.5) containing sulfur dioxide (SO₂) from coal-burning emissions is more deadly than PM_2.5 from other sources. Policymakers seeking to limit the impact of coal use justify regulations by quantifying the health burden attributable to exposure to these sources. However, measuring the magnitude of the impact of coal EGU-derived air pollution on human health, as well as the success of measures to mitigate such impacts, is challenging. Efforts have been hampered by the limited availability of large-scale health databases and source-specific exposure estimates.

To better estimate U.S. deaths attributable to exposure to PM_2.5 emitted from coal-burning power plants, and how related mortality patterns have changed over time, Lucas Henneman and colleagues combined a reduced complexity atmospheric transport model, which they used to estimate emissions from 480 individual coal EGUs, with historical individual-level US Medicare death records encompassing more than 650 million person-years. They found that exposure to coal-derived PM_2.5 was associated with 2.1 times greater mortality risk than exposure to PM_2.5 from all other sources. And, coal-derived PM_2.5 was responsible for 460,000 cumulative deaths among those over 65 years of age over the past two decades, accounting for ~25% of the total deaths attributable to PM_2.5. According to the findings, the mortality burden of coal PM_2.5 has been underestimated. Critically, Henneman et al. also show that the rapid decline of sulfur dioxide (SO₂) emissions from coal power plants over the last 20 years – through emissions reduction regulations and coal EGU closures – has led to a large reduction in excess deaths. In a related Perspective, Robert Mendelsohn and Seung Min Kim discuss the study and its limitations in greater detail. Note: The authors have provided an interactive online tool that illustrates how deaths attributed to each individual U.S. coal EGU have changed over time.