Hello to all,,in answer to your question Susan,,,

Radiation decays into inert radioisotopes on a Bell Curve;

It decays very little in the first couple of hours and then starts decaying rapidly over the next 12-24 hours, and then decays at slug speed for the next 2-4 weeks. This is primarily Alpha and Beta particles which will land (fall) on you first.

Gamma particles also decay on the Bell Curve but, the lower end of the Curve lasts much longer (months, years???). Most of these particles will be dead BEFORE they hit the ground because they were thrown (mostly) up into the upper atmosphere!!!

Neutron particles run "Hot" for 3 days and then they have burned out and the area is radiation free (of course, almost everyone within 30 miles are dead, also). Neutron radiation has twice the penetration of Gamma radiation (per a Nurse's Manual I have read).


Now figure the "weathering effect" of rain on the fallout particles. It rains, water pools some, and then runs off to drainage ditches, creeks, streams, rivers, and on to the sea; carrying these particles with it. Each time it rains, your surroundings are cleaned a little more. If you have a copy of the Kearney Fallout Meter(KFM-see Nuclear War Survival Guide for instructions and template), then you can monitor the amounts of fallout during your stay in your shelter and you will know when it is safe to come out.

It will however, be a long time before you want to get caught outdoors in a rainstorm,as the rain brings high level fallout back to Earth (still somewhat hot) to be washed away (eventually).

This is why the prospect of growing a garden will be so challenging among the many challenges brought to you by a few fools both locally, nationally, and internationally.

P.S: A chest X-Ray is approx 1/32nd of a Rem dosage.
150 Rems=Radiation Sickness
250 Rems=Military Command Dosage (When you're allowed to come back into the shelter & decontaminate to enjoy a slow painful death in about 1-14 days depending on the individual)
450 Rems=DEATH (and that's final forever)

Pigs and Chickens are reported to withstand radiation quite well although not nearly as well as cockroaches