By the Numbers: High-flying fallout

32 million

The weight in tons of the dust suspended in the atmosphere at any given time, half of which originates from North Africa. In January, scientists revealed in Science Advances that they had found radioactive material in a particularly massive 2022 dust storm, which deposited huge quantities of dust from the Sahara Desert on Western Europe.

0.187

The ratio of plutonium-240 to plutonium-239 particles in the samples, strongly indicating the fallout dust originated not from 1960 French nuclear tests in Algeria but from Cold War–era tests conducted by the Soviets and Americans thousands of miles away.

100 million

The number of similar radioactive dust storms that would need to hit Europe simultaneously to exceed radiation safety thresholds determined by European public health officials.

528

The number of atmospheric nuclear tests that have been conducted worldwide, according to the Arms Control Association.