The U.S. Environmental Protection Agency (EPA) issued a final rule reaffirming the basis for the 2012 Mercury and Air Toxics Standards (MATS) for power plants.  

The action reversed action that the Trump administration took in May 2020, which the Biden administration says undermined the legal basis for the mercury regulations. 

EPA said its final rule leaves the current emissions standards unchanged and continues public health protections provided by the requirements.

The agency said it also was continuing to consider the MATS Risk and Technology Review, as directed by Executive Order 13990, to determine whether more stringent protections for hazardous air pollution from power plants are feasible and warranted. It said it expects to address that review in a separate action.

The initial finding related to mercury emissions was made in 2000 and affirmed in 2012 and 2016. In May 2020, the Trump administration reversed EPA’s 2016 finding. President Biden’s Executive Order 13990 directed EPA to review that finding and consider an action to rescind it. 

EPA found that the 2020 action was based on a “fundamentally flawed” interpretation of the Clean Air Act that “improperly ignored or undervalued” health benefits from reducing hazardous air pollution from power plants. EPA said it was reaffirming that it is “appropriate and necessary” to regulate emissions of hazardous air pollutants from coal- and oil-fired power plants.

EPA estimated that by 2017, mercury emissions from power plants were reduced by 86%, acid gas emissions by 96%, and non-mercury metal emissions by 81% compared to pre-MATS levels in 2010. It also concluded that the cost for the power sector to comply with the MATS was “likely billions of dollars lower” than originally estimated. 

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