Don’t really need a unit of measure. Nuke plant said all radiation contained. Traces found blowing around on a street. Means it’s loose in the environment. Litmus test. Can’t be slightly pregnant or (radiation) slightly contained.
Uh...this isn’t about a “nuke plant”.
This is about particulate from the clean up of the waste storage.
Where did you get the idea “Nuke plant said all radiation contained.”???
These are trace amounts.
If you’re worried about these levels you’d better stay out of the sun.