On March 16, 2011, the Environmental Protection Agency proposed long-anticipated limits on power plant emissions of mercury and other hazardous air pollutants (“HAPs”) under Section 112 of the Clean Air Act (“CAA”). Along with recent emissions standards for industrial and commercial boilers and a new proposal for power plant GHG controls due out in July, EPA is undertaking a series of major CAA rule makings. EPA’s latest rule would establish the first nationwide standards for power plant emissions of mercury, arsenic and other HAPs, with numeric limits based upon maximum available control technology as required under the 1990 CAA Amendments. EPA’s new proposal would reduce mercury from approximately 525 coal and oil-fired power plants by 91 percent once fully implemented, and it covers a range of other pollutants that were not regulated under the Bush-era mercury rule.