The fallout products of an atomic bomb generally have short half lives. Wikipedia has some interesting graphs comparing the radiation dose of a fission bomb an

The fallout products of an atomic bomb generally have short half lives. Wikipedia has some interesting graphs comparing the radiation dose of a fission bomb and Chernobyl: http://en.wikipedia.org/wiki/Nuclear_fallout#Half-life http://en.wikipedia.org/wiki/Nuclear_fallout#Half-life