Fast Decay Rate??? It's here, but now I can't see it anymore with my counter so it's gone...
This is why I-131 is the big killer around a nuclear accident...
I-131 decays at a rate of 8 day halflife so 8X8 is 64 days before it is not considered harmful (although I personally don't believe that it's ever harmless)... A VERY big bang inside animals and humans (for a month or two). But, it simply does not have the time to travel very far from the original source.
Very Dangerous stuff!!!
Luckily we don't see much I-131 in our environment...
...unless you live in Japan.
HOWEVER...
Some isotopes of Radon have a half-life of around 3.8 days. Radon is one of the densest substances that remains a gas under normal conditions. It is also the only gas under normal conditions that ONLY contains radioactive isotopes. Radon is considered a health hazard due to its radioactivity and short halflife.
Notice that this is a VERY quick decay rate?
Firecracker, not campfire...
This stuff is literally everywhere and should be taken very seriously!
Funny how, now that we are looking for Fuku dust we are finding other sources of potent radioactivity that were already here.
Eat or breathe this stuff and someone will be opening your ketchup bottles for you for the rest of your short life...
http://www.radon.comhttp://geology.about.com/od/geophysics/a/aboutradon.htm