Fossil fuels also contain radioactive materials , mainly uranium and thorium , which are released into the atmosphere . In 2000 , about 12,000 tonnes of thorium and 5,000 tonnes of uranium were released worldwide from burning coal . It is estimated that during 1982 , US coal burning released 155 times as much radioactivity into the atmosphere as the Three Mile Island accident
Three Mile Island accident
Three Mile Island accident
Fossil fuel