The new rules would require many power plants to install technologies to control mercury, arsenic and other toxic air pollutants.
Environment Missouri's Ted Mathys says the new standards would help protect the health of Missourians.
"We know that because Missouri has a significant amount of mercury pollution from our coal fired power plants that these regulations will help protect Missouri's families and our wildlife from the dangerous effects of mercury pollution," Mathys said.
Ameren's Vice President of Environmental Services, Mike Menne, says the rule will require new pollution controls on every coal-fired plant the company owns. “We’re going to be attempting to control things that we’ve never tried to in the past,” Menne said.
Menne says installing the new technologies could cost hundreds of millions of dollars - costs he says could be passed on to customers.