Coal power plant pollution elevates mortality risk among Medicare users

Key takeaways:

• Between 1999 and 2020, 38.6 million Medicare users died, 460,000 of whom died because of pollution from coal power plants.
• This pollution vs. pollution from other sources heightened the risk for mortality.

Compared with fine particulate matter from any source, pollution from coal electricity-generating units heightened the risk for death by twofold among Medicare users, according to results published in Science.

“It’s important to acknowledge the added risk to health — including increased risk of heart and lung disease, cancer and death — posed by living in areas of high air pollution,” Lucas R. F. Henneman, PhD, assistant professor of environmental engineering at George Mason University, told Healio. “Living downwind of some air pollution sources (like power plants, as we found in this study) is even more dangerous.”

In a national study, Henneman and colleagues assessed individual-level Medicare death records that covered more than 650 million person-years to find out how many deaths from 1999 to 2020 were linked to exposure to fine particulate matter (PM_2.5) from coal electricity-generating unit (EGU), or power plant, sulfur dioxide emissions in the U.S. Because previous studies assumed PM_2.5 from coal has the same toxicity as from other pollutants, Henneman and colleagues used a different approach to measure coal PM_2.5 that accounts for date-specific atmospheric transport of PM_2.5 using a dispersion model.

In 2020, the annual average coal PM_2.5 level was 0.07 g m^–3, which signaled a reduction in this type of pollution since 1999 when the annual average level was 2.34 g m^–3.

Researchers found the risk for all-cause mortality went up by 1.12% with a rise of 1 g m^–3 in yearly average coal PM_2.5 (RR = 1.0125; 95% CI, 1.0113-1.0137).

Compared with data from a study that assessed the risk for mortality when exposed to PM_2.5 from any source in the same patient population, researchers found that those exposed to coal PM_2.5 faced an approximate 2.1 times higher risk for death.

“Previous studies were suggestive of this link, but ours was the largest to date and looked at variation in exposure and mortality in space and time,” Henneman told Healio.

Coal PM_2.5 exposure was linked to an estimated 460,000 deaths, or 1.2% of all 38.6 million Medicare deaths between 1999 and 2020.

A majority of the deaths linked to coal PM_2.5 took place between 1999 and 2007 (n = 390,000) when the yearly death rate was greater than 43,000. In comparison, in 2020, the number of excess deaths was 1,600.

Out of all deaths associated with PM_2.5 from any source, those linked to coal pollution in this population also went down as the year progressed (2000-2008, 25% vs. 2013-2016, 7%).

“The success story aspect [of this study] is important,” Henneman told Healio. “Annual deaths from coal power plants in our study fell from around 50,000 per year in 1999 to 1,600 in 2020. This was due to emissions regulations, decreased electricity demand and coal retirements (many coal plants have been replaced by natural gas plants, and use of renewables has been growing in recent years).”

Of the 480 U.S. EGUs included in this study, researchers found that pollution emitted from 10 of them led to more than 5,000 deaths each and pollution from 138 units each led to more than 1,000 deaths. Further, in every region, researchers found at least one power plant linked to more than 400 deaths.

Notably, power plants responsible for half of the nationwide coal EGU sulfur dioxide emissions between 1999 and 2020 were also responsible for 91% of deaths, according to researchers.

Both sulfur dioxide emission control installations and facility retirements lowered the number of people who died in each region. According to researchers, scrubber installations led to a reduction of an average of 640 deaths per year to 80 deaths per year caused by the Pennsylvania Keystone facility.

“I hope this inspires more research on impacts specific to various air pollutant sources,” Henneman told Healio. “The U.S.’s air quality is generally much improved compared to 2 decades ago, but we still see negative health impacts from air pollution. I think addressing the sources that contribute the largest impacts is important going forward, but we need better evidence of which sources are worse for health.”

For more information:

Lucas R. F. Henneman, PhD, can be reached at lhennem@gmu.edu.