In this task, we ask you to rewrite a sentence in simple English without changing its general meaning. Essentially, you want to make the sentence easier to read by using simpler words, utilizing more straightforward sentence structures, and omitting non-essential information etc.
Q: Nuclear fallout , or fallout , is the residual radioactive material propelled into the upper atmosphere following a nuclear blast , so called because it " falls out " of the sky after the explosion and the shock wave have passed .
A:
The name is because radioactive material " falls out " of the atmosphere into which it is spread during the explosion .