"Since then, scientists have said, mercury pollution from power plants has declined more than 80 percent nationwide".
The EPA's action, the release added, only proposes to correct flaws in MATS supplemental findings and is not proposing to "de-list" such power plants from the list of sources that are regulated under the Clean Air Act.
In July, electric utilities and utility groups favoring the rule asked the administration to keep it in place.
Since August, the Environmental Protection Agency has been reconsidering the justification for the rule.
The Trump administration's Environmental Protection Agency is taking aim at an Obama-era regulation that seeks to reduce mercury pollution from coal-fired power plants.
The mercury regulation also costs the coal industry $9.6 billion annually, making it among the most expensive regulations the EPA has ever had to enforce.
"There is nobody who operates power plants who is asking for the rule to go away", said Jeffrey R. Holmstead, a partner at the law firm Bracewell who served as EPA air chief under the second President George Bush.
A proposal Friday from the Environmental Protection Agency challenges the basis for the Obama regulation. Mercury harms the developing nervous systems of children and causes other severe health damage.
Estimates like that, however, are at the heart of the current dispute. It said the standards have markedly reduced mercury in the environment and improved public health.
According to the Times reporting, the new proposed rule would change the way the EPA determines the benefits of limiting different types of emissions, potentially making it more hard in the future for the agency to create new regulations.
If adopted, the change would prevent regulators from calculating positive health effects - known as "co-benefits" - that come from reducing pollutants other than those being targeted. "The misguided proposed changes leave MATS legally vulnerable and foolishly make it harder to strengthen mercury pollution reduction standards in the future to better protect children's and women's health, and Great Lakes fisheries". It would consider only the benefits that can be directly translated into dollars and cents.
"The administrator has concluded that the identification of these benefits is not sufficient, in light of the gross imbalance of monetized costs", the EPA announcement read.
The National Mining Association praised the move, saying the mercury regulations are "punitive" and "massively unbalanced". "It's a very different calculus". This is public health benefits.