Besides the gases emitted from coal-fired power plants, a huge amount of fly ash containing HAPs is produced from the burned coal. At Rawhide, 70,000 tons of fly ash are produced annually, which has to be captured in bag filters and disposed of. Some of it is used to make cinder blocks and sheetrock, but the vast majority is simply buried as a dry waste that is then covered with two feet of soil and planted in native grasses. This is relatively benign, but that is not how many coal power plants handle ash. Many power plants store the ash as wet sludge in large hold­ing ponds, which can leak or spill. About 100 million tons of ash and sludge are produced annually in the United States from coal-fired power plants (10). In 2008 coal ash sludge broke through the dike of a 40-acre holding pond in Tennessee, covering 400 acres up to six feet deep with toxic sludge, contaminating a river and damaging a dozen houses (11). And this was a small ash holding pond. The Plant Scherer coal-fired plant in Monroe County, Georgia—the largest coal-fired plant in the United States—has an ash holding pond that is about 19 times as large as the one that failed in Tennessee, with over 1,000 tons of coal ash deposited daily (12). In 1972 an impoundment dam failed in Logan County, West Virginia, and spilled 130 million gallons of toxic sludge into Buffalo Creek, killing 125 people, injuring 1,000, and leaving 4,000 people homeless (13).

Bag filters and electrostatic filters are not able to remove the smallest particles resulting from the fly ash, however. Particulates are classified in terms of their diameter in microns (millionths of a meter). PM10 particles have a diameter of 10 microns or less (roughly the size of a cell in your body) and PM2 5 particles have a diameter of 2.5 microns or less, a small fraction of the width of a human hair. These smaller PM2 .5 particles are not easily removed from the coal-fired plant exhaust and are the most hazardous. They can accumulate in the deepest recesses of the lung and lead to respiratory diseases such as emphysema and lung cancer. A study done for the Clean Air Task Force estimated that there were over 30,000 premature deaths in the United States from power plant emissions in 2000 (14). A more recent Clean Air Task Force study estimated that there would be 13,200 deaths in 2010 (15). While studies vary considerably in estimating the annual number of deaths from these particles, it seems clear that the numbers are in the thousands or tens of thousands. A study by the National Academy of Sciences put the annual cost of damages due to air pollution from coal at $62 billion in 2005 (16).