radioactive fallout

particles charged with radioactive material that were created due to an atomic explosion

Fallout is the residual radiation hazard from a nuclear explosion, so named because it "falls out" of the atmosphere into which it is spread during the explosion. It commonly refers to the radioactive dust created when a nuclear weapon explodes. This radioactive dust, consisting of hot particles, is a kind of radioactive contamination. It can lead to contamination of the food chain. Fallout can also refer to the dust or debris that results from the nuclear explosion.
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[RAY-dee-o-AK-tiv]
Airborne radioactive particles that fall to the ground during and after an atomic bombing, nuclear weapons test, or nuclear plant accident.

1. The return to the lower atmospheric layers and to earth of radioactive substances projected to high altitude. 2. Contaminated particulate matter and debris absorbed into the cloud of a nuclear burst. 20/11/96