system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 How can people still live in Hiroshima and Nagasaki when they can't live in Pripyat or the Bikini Atoll?

And if the answer is that there's less radiation, then why is that?
gpt
The bombs used in Hiroshima and Nagasaki exploded in the air, so **ALOT** less radiation seeped into the environment. 

In Chernobyl, the worker city outside Pripyat, the disaster was a leak, followed by an explosion. This put lots of radiation into the surrounding environment.

edit: Also the International Atomic Energy Agency has deemed Bikini Atoll safe to walk, even the fruits are said to be no cause for concern on the island. It's just that it has more radiation that the other islands, which isn't much.