Looking at the decay chain of U-238 [0], some of the descendants of radon-222 have extremely short half-lives. [0] http://en.wikipedia.org/wiki/Uranium-238#Rad

Looking at the decay chain of U-238 [0], some of the descendants of radon-222 have extremely short half-lives. [0] http://en.wikipedia.org/wiki/Uranium-238#Radium_series_.28or_uranium_series.29 http://en.wikipedia.org/wiki/Uranium-238#Radium_series_.28or...