Originally Posted by
TURIN
Yes, but in regard to the OP, if flying thousands of feet above it as a passenger or crew, it is not something to be immediately concerned about.
Not at all true. The contamination is in the form of aerosols, i.e micro particles suspended in the air. They can travel thousands of miles and at any altitude (distance and dispersion will depend on particle size and density)
The nature of these beta emitters means that even a single particle breathed in COULD cause health risks.
Can we do anything about it / Is there cause to worry? - Probably not, its already spread, and we found out much later than the accident (that Russia are not even officially acknowledging).