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Public Health Benefits Associated with Mercury Emissions Reductions from U.S. Power Plants

04/11/2022 | Harvard Chan C-CHANGE

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The United States Environmental Protection Agency (EPA) released their revised analysis supporting the Appropriate and Necessary (A&N) determination underlying the Mercury and Air Toxics (MATS) Rule on January 31, 2022.

An updated white paper by researchers from Harvard T.H. Chan School of Public Health, Harvard John A. Paulson School of Engineering & Applied Sciences, Harvard Law School, and Syracuse University strongly supports the EPA proposal to revoke the 2020 reconsideration, and to affirm the 2016 supplemental finding that it is appropriate and necessary to regulate hazardous air pollutant (“HAP”) emissions from power plants.

As part of the analysis, the researchers outline several shortcomings in the proposed rule, arguing that EPA could have used a technical approach to strengthen the rule with the best-available scientific information to assess the public health benefits associated with reductions in mercury emissions from U.S. coal-fired power plants. The white paper provides a quantitative analysis of the mercury exposure pathway for U.S. individuals in the general population and recreational fishers.

A previous white paper, Mercury Science and the Benefits of Mercury Regulation was released in December 2021.

Key takeaways

  • There was a 90% reduction in mercury emissions from U.S. power plants between 2008 (26.8 Mg) and 2020 (2.8 Mg) totaling 24 Mg.
  • Updated atmospheric chemistry modeling suggests the average deposition of mercury attributed to coal-fired power plants is approximately twice as large as EPA’s estimate.
  • This increase in domestic deposition from coal-fired power plants reflects the improved understanding of how mercury is released from coal-fired power plants and chemical reactions that occur in the atmosphere that should be incorporated into EPA’s analysis.
  • New modeling by the research team suggests reductions in power plant mercury emissions between a 2008-2010 baseline prior to the rule and 2020 led to:
    • 60,000-100,000 women of childbearing age (16-49) shifting from above to below the EPA’s Reference Dose (RfD)—which is meant to convey a “safe” level for methylmercury exposures—and 3,700-5,600 fewer babies born per year with exposures above the RfD.
    • A decreased share of the U.S. population exposed to mercury levels above those associated with increased risk of ischemic heart disease by 380,000 individuals, and cardiovascular mortality by 160,000 individuals.
    • $1.2-1.5 Billion USD in benefits to public health due to reduced cardiovascular mortality, which exceeds the upper bound proposed by EPA.


  • Elsie Sunderland, Harvard John A. Paulson School of Engineering & Applied Sciences and Harvard T.H. Chan School of Public Health, Department of Environmental Health
  • Colin Thackray, Harvard John A. Paulson School of Engineering & Applied Sciences
  • Mona Dai, Harvard John A. Paulson School of Engineering & Applied Sciences
  • Ben Geyman, Harvard John A. Paulson School of Engineering & Applied Sciences
  • Shaun Goho, Emmett Environmental Law & Policy Clinic, Harvard Law School
  • Charles Driscoll, Department of Civil and Environmental Engineering, Syracuse University