Reduction of mercury emission from coal combustion is an effect of implementation of technologies for controlling conventional air pollutants ( particulate matter , SO2 and NOx ) and specific technologies for heavy metal removal . Examples from US power plants reported in the United States Government Accountability Office ( GAO ) -10-47 ( 2009 ) and NESCAUM ( 2010 ) report indicate that mercury control is being achieved at commercial scale at many power plants at relatively low costs using carbon injection , but alternative control measures may be needed in some cases .