With all the talk about dirty bombs and certain hostile countries about to join the A-Bomb club it might be a good time to know how to build a home made fallout meter. At least print out the file and put it in your Prepping Notebook (You do have one don't you).

http://www.abomb1.org/pdf/kfm_inst.pdf

Originally developed at Oak Ridge National Laboratory for use in Civil Defense during the Cold War.