Mortality risk from United States coal electricity generation

Abstract

Policy-makers seeking to limit the impact of coal electricity-generating units (EGUs, also known as power plants) on air quality and climate justify regulations by quantifying the health burden attributable to exposure from these sources. We defined "coal PM_2.5" as fine particulate matter associated with coal EGU sulfur dioxide emissions and estimated annual exposure to coal PM_2.5 from 480 EGUs in the US. We estimated the number of deaths attributable to coal PM_2.5 from 1999 to 2020 using individual-level Medicare death records representing 650 million person-years. Exposure to coal PM_2.5 was associated with 2.1 times greater mortality risk than exposure to PM_2.5 from all sources. A total of 460,000 deaths were attributable to coal PM_2.5, representing 25% of all PM_2.5-related Medicare deaths before 2009 and 7% after 2012. Here, we quantify and visualize the contribution of individual EGUs to mortality.

Fig. 1.. ZIP code–level coal PM_2.5 over time.

Box plots (median, first, and third quartiles are shown as horizonal lines and outliers as dots) summarize the distribution of ZIP code levels of coal PM_2.5. Map areas shown in white do not have ZIP codes. Plots were produced in R using ggplot2; spatial information comes from the USAboundaries package.

Fig. 2.. Annual number of excess deaths attributable to coal PM_2.5, estimated using the RR for coal PM_2.5 from this study and RRs for total PM_2.5 from the literature.

All excess deaths are estimated relative to zero coal PM_2.5. The area filled by horizontal hashing indicates deaths estimated using RRs derived from this study (bounds represent 95% CI). Areas filled by vertical and diagonal hashing correspond to deaths estimated using RRs for total ambient PM_2.5 exposure from the literature (4, 33). The gray shaded region from 2017 to 2020 represents years for which ZIP code–specific baseline death rates were assumed from the 2014 to 2016 average. This figure was produced in R using ggplot2.

Fig. 3.. Excess deaths associated with individual coal EGUs from 1999 to 2020.

EGUs (N = 480) are organized by region to improve interpretability, and the facilities associated with the most deaths are labeled. Inset: total SO₂ emissions by location from 1999 to 2020 (hexagonal grids may include multiple EGUs) and regional boundaries. Plots were produced in R using ggplot2; spatial information comes from the USAboundaries package.

Fig. 4.. Total annual excess deaths associated with each of the coal EGUs in each region, with the two most harmful facilities highlighted.

Scrubber installations designate the earliest year that a scrubber was installed at one or more of each EGU’s units [facility information from (46)]. Plots were produced in R using ggplot2.