Polonium were marketed by Firestone from 1940 to 1953. While the amount of radiation from the plugs was minuscule and not a threat to the consumer, the benefits of such plugs quickly diminished after approximately a month because of polonium's short half-life and because buildup on the conductors would block the radiation that improved engine performance. (The premise behind the polonium spark plug, as well as Alfred Matthew Hubbard's prototype radium plug that preceded it, was that the radiation would improve ionization of the fuel in the cylinder and thus allow the motor to fire more quickly and efficiently.) Polonium is
Polonium hydride and hydrogen selenide, and decomposes into its constituent elements, releasing heat in the process. The amount of heat given off in the decomposition of polonium hydride is over 100 kJ/mol, the largest of all the hydrogen chalcogenides. Polonium hydride is a liquid due to van der Waals forces, and not due to the same reason as why water (hydrogen oxide) is liquid (hydrogen bonding). It is predicted that, like the other hydrogen chalcogenides, polonium may form two types of salts: polonide (containing the Po anion) and one from polonium hydride (containing –PoH, which would be the polonium analogue of thiol,