I gotta call BS on that. No way.
Agreed! If you look at the atmospheric dispersion and absorption of X Rays, gamma Rays, etc. it makes that assertion highly suspect!
Going from memory here, from reading about it, it wasn’t actually in Rochester, NY, at least at first. It was first noticed in Iowa or someplace like that. Unexplained fogging of negatives or unexposed film. It was sent to Rochester where they tried to figure out what was going on. Of course due to the secrecy requirements it was a big deal. The Trinity test and subsequent tests did put fissionable material into the atmosphere, and caused problems with retail film in various parts of the country. It also caused elevated levels of radiation in dairy milk, due to cows grazing on pastures in the midwest.