New E.P.A. Plan Could Free Coal Plants to Release More Mercury Into the Air

In the proposal, the Environmental Protection Agency issued a finding declaring that federal rules imposed on mercury by the Obama administration are too costly to justify.

It drastically changed the formula the government uses in its required cost-benefit analysis of the regulation by taking into account only certain effects that can be measured in dollars, while ignoring or playing down other health benefits.

The result could set a precedent reaching far beyond mercury rules. “It will make it much more difficult for the government to justify environmental regulations in many cases,” said Robert N. Stavins, a professor of environmental economics at Harvard University.