In this July 27, 2018 file photo, the Dave Johnson coal-fired power plant is silhouetted against the morning sun in Glenrock, Wyoming.

(AP Photo/J. David Ake, File)

At a Glance

The EPA used a different cost analysis formula than the one used by the Obama administration.The agency said the rules were no longer "appropriate and necessary" to regulate mercury and toxic air pollution from coal and oil-fired power plants.

A proposed plan by the Environmental Protection Agency would allow coal- and oil-fired power plants to resume emitting higher amounts of mercury and other hazardous air pollutants (HAPs) into the environment.

The Mercury and Air Toxics Standards (MATS) were enacted by the Obama administration in 2011. They led to an $18 billion cleanup of mercury and other toxins from the smokestacks of power plants, the largest contributor of mercury pollution in the environment.

Environmentalists say the rules have eliminated up to 85 percent of the mercury released into the environment over the past decade or so, the Associated Press reported.

In late December, the EPA that would roll back the rules.

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They agency challenged the basis of Obama's rules for power plants, saying the standards only contribute a few million dollars a year in measurable health benefits. The EPA added that it is not "appropriate and necessary" to regulate HAP emissions, including mercury, from coal- and oil-fired power plants.

The agency changed the formula used by the Obama administration to calculate the required cost-benefit analysis of the standards and determined the costs to utilities of around $7.4 billion to $9.6 billion "dwarfs" the estimated health benefits of $4 million to $6 million.

The Obama administration calculated , the New York Times reported, by taking into account so-called "co-benefits" that occur when mercury and other toxic pollutants are reduced, including the reduction of particulate matter to help prevent asthma, heart disease and lung diseases.

The Obama administration estimated that the rules would prevent 11,000 premature deaths each year.

The Trump administration's new cost analysis formula ignores co-benefits and only calculates the health costs directly tied to mercury and other HAPs.

Hal Quinn, president of the National Mining Association, , calling the limits for power plants "perhaps the largest regulatory accounting fraud perpetrated on American consumers."

"By suppressing the real costs while double-counting potential benefits, the last administration made American households and businesses pay $960 in exchange for 60 cents in potential benefits," Quinn said. "Surely EPA will now understand that no rational person would voluntarily agree to such a massively unbalanced arrangement."

Others condemned the move.

Sen. Tom Carper (D-DE), who serves on the Senate's Environment and Public Works Committee, said the decision puts .

"Once again, the Trump Administration is acting in a way that will adversely affect the health and safety of those living from coast to coast," Carper said. "The Trump EPA has decided – despite the recommendations of scientists, public health experts and elected officials on both sides of the aisle – that it is no longer 'appropriate and necessary' to protect the development of infants’ brains from the serious threats posed by mercury power plant pollution."

American Lung Association president Harold Wimmer said in a statement that "there is for this action."

"The 2011 standards prevent up to 11,000 premature deaths a year and cut mercury pollution, a potent neurotoxin that causes brain damage in babies," he said.