A bipartisan group of senators today introduced a long-awaited bill aimed at slashing harmful air pollutants from coal-fired power plants. The bill from Sens. Tom Carper (D-Del.) and Lamar Alexander (R-Tenn.) would mandate steep cuts in electric utilities' emissions of mercury and soot- and smog-forming pollution. It aims to cut soot-forming sulfur dioxide (SO2) by 80 percent by 2018, smog-forming nitrogen dioxide (NOx) by 53 percent by 2015 and mercury by 90 percent by 2015.