- "There is no medicine that will effectively prevent nuclear radiations from damaging the human body cells that they strike."
- "KI provides protection only for the thyroid from radioiodines. It has no impact on the uptake by the body of other radioactive materials and provides no protection against external irradiation of any kind. FDA emphasizes that the use of KI should be as an adjunct to evacuation (itself not always feasible), sheltering, and control of foodstuffs."
However, there are numerous other, and very dangerous, radioactive noble gases and/or radioactive fallouts that can be associated with nuclear emergencies. You are still exposed to inhale, ingest, or be radiated externally from any number of dangerous non-radioiodine sources.
If you are ever directed to evacuate in a nuclear emergency, do so immediately, regardless of whether you have taken Potassium Iodide (KI) or KIO3, or not.
Note: KI or KIO3 would likely not be needed for the so-called "Dirty Bomb" or RDD (Radiological Dispersal Device). Radioactive Iodine is only produced by a fission or fusion weapon detonation or in a Nuclear Power Plant as a byproduct of that process. An RDD simply spreads around existing radioactive material and it's not very likely to have been composed of the relatively short half-life radioactive iodine. We'd more likely see used in an RDD a commercially abundant, and more easily obtained, isotope like Cobalt-60, Cesium-137 or uranium fuel rods, etc.