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
Synthetic element short half-lives. The following elements do not occur naturally on Earth. All are transuranium elements and have atomic numbers of 95 and higher. All elements with atomic numbers 1 through 94 are naturally occurring at least in trace quantities, but the following elements are often produced through synthesis. Except for polonium, francium, actinium, and protactinium, they were all discovered through synthesis before being found in nature. Synthetic element In chemistry, a synthetic element is a chemical element that does not occur naturally on Earth, and can only be created artificially. So far, 24 synthetic elements have been created (those with