I don't believe that there are any significant I-131 production mechanisms within the decay chains of the fallout. Iodine 131 has an eight day half life. The a

I don't believe that there are any significant I-131 production mechanisms within the decay chains of the fallout. Iodine 131 has an eight day half life. The accident was 12,409 days ago. There is <2^{-1500} of the iodine remaining. For scale, if the Earth were made entirely, by mass, from I-131 on the day of the accident, there would have been ~10^50 nuclei. All of those nuclei would have decayed into daughters within the first four years. There is certainly plenty of residual radioactivity from Chernobyl, with which one might be concerned regarding forest fires. The specific hazard against which potassium iodide provides protection, however, is no longer present.