Radium, polonium and radon may be names to make your hair stand on end, but are they actually useful for anything? And is our fear of them overbaked? Laurence Knight gets the chemistry rundown from Prof Andrea Sella of University College London at a hospital that used to treat cancer with radiation. Al Conklin of the Washington State Department of Health explains how we are still dealing with the world's early Twentieth Century craze for all things radioactive. Edwin Lane reports from Finland on how the country's geology and climate conspired to fill their houses with a radioactive gas. Plus, we hear from Prof Norman Dombey, a key expert witness in the public enquiry into the murder of Alexander Litvinenko.

(Picture: Glow-in-the-dark radium clock dial; Credit: Ted Kinsman/Science Photo Library)