Coal-fired power plants produce more than just carbon dioxide, which contributes to global warming. Coal burning also releases particulate matter, sulphur dioxide, nitrogen oxide and mercury—thus damaging the health of many people around the world. To estimate where action is most urgently required, the research group led by Stefanie Hellweg from ETH Zurich’s Institute of Environmental Engineering modeled and calculated the undesired side effects of coal power for each of the 7,861 power plant units in the world.