 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 plug to fire more quickly and efficiently.The side electrode (also known as the "ground strap") is made from high nickel steel and is welded or hot forged to the side of the metal shell.