Hiroshima and Nagasaki were bombed in 1945, despite conspiracy theories

"Hiroshima and Nagasaki were never nuked," reads the caption of a recent Facebook video that suggests both Japanese cities would be uninhabited if they had been bombed because of the half-life of the chemicals used in the weapons. 

"Hiroshima is a bustling city with a population of over 2 million people," the video’s narrator says. "In the smaller city of Nagasaki, almost 400,000 people. Are these two cities thriving in a nuclear wasteland or"; the video then loops back to the start. 

This post was flagged as part of Meta’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Meta, which owns Facebook and Instagram.)

The United States bombed Hiroshima on Aug. 6, 1945, and Nagasaki on Aug. 9, "killing tens of thousands of people" and "obliterating cities," by the U.S. government’s own admission. 

More died in the attacks’ wake "because of the lingering effects of radioactive fallout."

But for all practical purposes, neither city is still radioactive, according to the Radiation Effects Research Foundation, a cooperative research effort between the United States and Japan.

The Hiroshima and Nagasaki bombs exploded at altitudes of 600 and 503 meters, respectively, forming huge fireballs that rose with air currents, according to the foundation. About 10% of the nuclear material in the bombs underwent fission — one of two ways residual radioactivity is produced from an atomic blast — and contaminated the ground. 

Featured Fact-check

X posts

stated on September 20, 2024 in an X post

First lady Jill Biden led a Cabinet meeting for President Joe Biden and her signature appears on presidential stationery.

About 90% of the nuclear material rose in the stratosphere with the fireballs, and some of it fell with rain as the material cooled down, "but probably most of the remaining uranium or plutonium was dispersed widely in the atmosphere," according to the foundation. 

Today, the radioactivity is so minuscule that it’s difficult to distinguish from trace amounts of radioactivity caused by fallout from atmospheric atomic bomb tests conducted around the world in past decades, the foundation says. 

The city of Hiroshima says on its website that the radiation present in both cities "has no effect on human bodies."

We rate claims that neither Hiroshima nor Nagasaki were attacked with atomic bombs Pants on Fire!