influence on the severity of fallout is where the detonation
occurred, whether at ground level in a 'ground burst' or in midair as
an 'air burst'. The ground burst would be the worst case scenario as
the fallout will be augmented by the addition of extra displaced
The air burst, however, becomes more cloud-like more quickly;
and without large material to become irradiated, the particles tend
to be finer and linger in the upper atmosphere for longer until
finally coming down, by which time the materials have been diluted by
the sheer amount of space they occupy. Both ground and air bursts are
bad, just one is very slightly worse.
range and scope of fallout is also affected by the type of area in
which it occurs. In urban centres with high building density the
fallout will settle relatively close to the blast location. In wide
open locations, such as deserts or remote islands in Micronesia,
there are fewer barriers to prevent the particles from spreading
across a broader area.
also play a big part into determining the locations most affected by
fallout, as the wind can carry particles in whatever direction it
happens to be blowing so the people most in danger from the more
immediate effects of fallout will be those downwind from the blast.