Progress Report

Emission Reductions


Source: EPA, 2021
Last updated: 05/2021

Related Figures

Mercury Emissions from MATS Sources, 2010–2019
State-by-State Mercury Emissions from MATS Sources, 2019


Overall Results

  • Mercury and other hazardous air pollutant (HAP) emissions have declined significantly since 2010 estimates. These emission reductions were driven by the installation of new pollution controls and enhancements of existing pollution controls that reduce multiple pollutants. Emissions have also decreased due to operational changes, such as fuel switching and increased generation at natural gas-fired units that emit very little mercury and other HAPs. These trends are discussed in Chapter 1.
  • Other programs – such as regional and state SO₂ and NOₓ emission control programs – also contributed to the mercury and other HAP emission reductions achieved by covered sources in 2020.

Mercury and Hazardous Air Pollutant Emission Trends

Compared to 20101, units covered under MATS in 2020 emitted 26 fewer tons of mercury (91% reduction).

  1. Emissions from 2010 are estimated as described in Memorandum: Emissions Overview: Hazardous Air Pollutants in Support of the Final Mercury and Air Toxics Standard. EPA-454/R-11-014. November 2011; Docket ID No. EPA-HQ-OAR-2009-0234-19914.

Background Information

Hazardous air pollutants (HAPs) emitted by power plants include mercury, acid gases (e.g., hydrochloric acid, hydrofluoric acid), non-mercury metallic toxics (e.g., arsenic, nickel, and chromium) and organic HAPs (e.g., formaldehyde, dioxin/furan). Exposure to these pollutants at certain concentrations and durations can increase chances of cancer and immune system damage, along with neurological, reproductive, developmental, respiratory, and other health problems.

In 2011, EPA issued MATS, establishing national emission standards for mercury and other hazardous air pollutants for new and existing coal- and oil-fired power plants. The standards were finalized under section 112 of the Clean Air Act. The MATS emission standards were established using data from a 2010 information collection request (ICR) that was sent to selected coal- and oil- fired EGUs.