The mass of radioactive material in the mushroom cloud did not disperse as expected, but stayed in a small volume of atmosphere as it traveled eastward.

Finally, a couple of days later it became entrained in a severe thunderstorm over New York's Capital District, and most of the radioactive material washed out over a fairly small region (Washington and Rensselaer counties).

Students in a radiochemistry laboratory at Rensselaer Polytechnic Institute in Troy, New York switched on their geiger counters only to discover radiation levels hundreds of thousands of times higher than normal.

Assuming a radioactive spill inside the building, the students were rushed outside to safety – only to discover radiation levels even higher.

Later he was warned to stay silent, lest he lose access to AEC materials, or even face arrest for treason.