MATS

EPA has already taken some steps toward updating power plant rules to set tighter limits on non-greenhouse gas pollutants, including taking public comment on the possibility of strengthening MATS.

In its justification for MATS, the Obama administration accounted for indirect benefits of installing mercury pollution-control equipment at coal plants that included things like reduction of deadly emissions of particulate matter.

In a somewhat wonky sleight of hand and one that does not bode well for future clean air protections, the agency has proposed a revision to its own finding on MATS.

Washington State University, a five-hour drive from Amazon's Seattle headquarters, received U.S. funding and became the research hub for MATS.

Pruitt, in his previous role as attorney general of Oklahoma, had sued the EPA to stop the rule, which is known as MATS.