How deadly is Radioactive Fallout?- Explained (Patreon)

'The worst uncontrolled release of radioactive material in history'

Sound scary until you realize that half of that radiation was actually a radioactive gas, xenon.  However from almost the second of its release it was so diluted that no one worried about it!

External radiation doses are trivial to avoid- you just leave the area and discard contaminated clothing.

Internal can be more difficult to avoid if the radioactivity is mobile in the environment.  This mobility depends on the chemistry of the isotope.

Cesium is water soluble, but doesnt bioaccumulate in humans (it has a biological halflife of ~70 days).

Iodine 131 bioaccumumulates but has such a short half life that after about a month, 90% of it has decayed and after 2 years not one single radioactive nucleus is left.

Strontium also bioaccumulates, but also tends to be immobile in the environment (it tends to precipitate out as things like strontium carbonate.

These are the big hazards to human health.  All the others decay so quickly that they cease to become a problem after a few days, are even less mobile in the environment than strontium, or have such long half lives that cant significant radiation doses.  30 years after Chernobyl almost the only isotope that people worry about is cesium.

This is the reason why the only people to get acute radiation sickness were either at the reactor when it exploded or poked around the exploded core of the reactor without protective clothing.