Changes

==Burning==

When coal is burned, toxins in the coal are released into the smokestack. With modern air pollution controls, airborne toxins are captured through filtration systems before they can become airborne, and contained in a fine ash called [[coal ash]], [[fly ash]], or [[coal waste]]. As a result, heavy metals such as mercury are concentrated in what the EPA considers "recycled air pollution control residue."<ref name="union">[http://www.timesunion.com/AspStories/story.asp?storyID=733185&category=REGION&TextPage=1 "Fly ash: Culprit at Lafarge? Residue of coal-burning is being examined as possible source of mercury pollution,"] ''Times Union,'' October 26, 2008.</ref>