Elevated atmospheric radioactivity remains measurable after the widespread nuclear testing of the 1950s.

Its radioactive characteristics increase the statistical cancer risk. This size of particulate matter, lifted to the stratosphere, may take months or years to settle, and may do so anywhere in the world. Its amount can be estimated from the fission-fusion design and yield of the weapon.Īfter the detonation of a weapon at or above the fallout-free altitude (an air burst), fission products, un-fissioned nuclear material, and weapon residues vaporized by the heat of the fireball condense into a suspension of particles 10 nm to 20 µm in diameter. When the nuclear fireball does not reach the ground, this is the only fallout produced. These materials are limited to the original mass of the device, but include radioisotopes with long lives. The second, depending on the height of detonation, is a large quantity of radioactive dust and sand with a short half-life.Īll nuclear explosions produce fission products, un-fissioned nuclear material, and weapon residues vaporized by the heat of the fireball. The first is a small amount of carcinogenic material with a long half-life. Atmospheric nuclear weapon tests almost doubled the concentration of radioactive 14C in the Northern Hemisphere, before levels slowly declined following the Partial Test Ban Treaty.įallout comes in two varieties.

Fallout 2 energy weapons