Remind Pruitt of Mercury and Air Toxics (MATS) for power plants and boilers is still a thing EPA has to consider. There isn’t a truly feasible technology to deal with mercury from coal plants. By feasible I mean: the system is full scale and operable, the system is effective at achieving mercury emissions control, the system is implementable considering all things, and the system is economically sound in marketplace that includes gas and renewables. Mercury is slithery and that’s why it’s called quick silver and is hard to filter. On the other hand, the average age of Sunday talk show viewers is about 65 — so it’s not like mercury poisoning is more of a concern than say erectile dysfunction and bladder control.
Edit to add: EPA still considers MATS here