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 easily if polonium is ingested, inhaled, or absorbed, although they do not penetrate the epidermis and hence are not hazardous as long as the alpha particles remain outside the body. Wearing chemically resistant and intact gloves is a mandatory precaution to avoid transcutaneous diffusion of polonium directly through the skin. Polonium delivered in concentrated nitric acid can easily diffuse through inadequate gloves (e.g., latex gloves) or the acid may damage the gloves. It has been reported that some microbes can methylate polonium by the action of methylcobalamin. This is similar to the way in which mercury, selenium, and tellurium are