Now that the national government has finally owned up to the existence of plutonium and strontium outside Fukushima I Nuclear Power Plant (in case of strontium-89, as far as Shirakawa City, 79 kilometers from the plant), it seems like a good time to revisit what the government researchers were saying about "heavy" plutonium that we didn't need to worry about a bit, back in March and April.
Particularly the second guy, Keiichi Nakagawa of Tokyo University, said plutonium was so heavy it wouldn't disperse, and only the workers at the plant needed to worry.
(From my post on 8/8/2011)
Nakagawa: To begin with, this material is very heavy. So, unlike iodine, it won't disperse in the air. Workers at the plant MAY be affected. So, I'd caution them to be careful. But I don't think the public should worry.