The Trump administration is reviewing a major Obama-era clean air regulation on the emission of mercury — a pollutant linked with damage to the brain, to the nervous system and to foetal development — with the intent of proposing a replacement rule, a spokeswoman for the Environmental Protection Agency said on Wednesday.

The EPA's review of the 2011 mercury rule comes amid a string of initiatives by the Trump administration to roll back or weaken many environmental regulations put forth by the Obama administration. After reviewing the rule, a process which typically takes 60 to 90 days, the EPA will issue a proposed replacement rule, the agency spokeswoman, Molly Block, said in an email.

The mercury regulation under review chiefly affects pollution from coal-fired power plants. The move comes as President Donald Trump has pressed forward on numerous fronts in an attempt to meet his campaign pledge to revive the nation’s coal industry, despite economic analyses showing that the decline in demand for coal is largely driven by market forces rather than regulations.

Last week, the EPA proposed a new rule designed to replace the Clean Power Plan, another major Obama-era regulation governing coal-fired power plants. That rule would have restricted coal plants’ emission of a different pollutant: carbon dioxide, one of the chief causes of global warming.

At the time the Obama administration put forth the mercury regulations, which took more than 20 years to formulate, EPA officials estimated they would save thousands of lives and return economic and health benefits many times their estimated $9.6 billion annual cost.

While owners of coal plants fought the rule in the courts, most have since complied with regulation. Because coal plant owners have already invested in the technology required to lower mercury pollution, some analysts say, it makes little sense to change the regulation now.

“This is reckless chaos for the sake of chaos,” said John Walke, an expert on the Clean Air Act with the Natural Resources Defence Council, an advocacy group. “The power sector is fully complying and has appealed to EPA publicly, with labour organisations, to leave the standards alone.”

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If the agency rolls back the rules, he said, it raises the prospect that “coal plant owners will face legal challenges to prior utility-commission approvals of pollution-control costs incurred to meet those obligations.”

In 2015, in a victory for opponents of the mercury rule, the Supreme Court concluded that the EPA did not appropriately consider the costs to industry when crafting the rule and directed the EPA to recalculate those costs. The Obama administration then reissued the rule in 2016, and power plants have complied with it since then.

Jeffrey Holmstead, a lawyer who represents coal-burning electric utilities and who served in the EPA under former President George W Bush, said in an email he was “not surprised” that the agency was reviewing the Obama-era finding that it was “appropriate and necessary” to regulate power plants for mercury pollution considering that several Supreme Court justices “expressed scepticism about the argument that the Obama EPA made to support its second finding, which the current EPA is now reviewing.”

Mr Holmstead said, however, that he did not expect the Trump administration to try to eliminate a rule on mercury pollution entirely. “It would serve no purpose because the power sector has already spent billions of dollars to bring all their plants into compliance.”