The problems with coal ash start smaller than anyone thought: How well toxic elements leach out of coal ash depends on the ash's nanoscale composition

Burning coal doesn't only pollute the air. The resulting ash can leach toxic chemicals into the local environments where it's kept. New research shows that the toxicity of various ash stockpiles relies heavily on its nanoscale structures, which vary widely between sources. The results will help researchers predict which coal ash is most environmentally dangerous.