Radioactive Fallout

If a nuclear weapon is exploded on, or near, the ground, danger from radioactive fallout is greatest. The force of the explosion may make a crater up to a mile wide and to a depth of one hundred feet. Millions of tons of pulverized earth, stones, buildings and other materials are drawn up into the fireball and become radioactive.

Some of the heavier particles spill out around the point of explosion. The rest are sucked up into the mushroom cloud. This radioactive material is then carried by winds until it settles to earth. This is called "fallout". Material that is affected by radioactive fallout is called contamination.

Under some circumstances you may see the fallout; under others you may not. The radioactivity it gives off cannot be seen. You can't feel it. You can't smell it. But fallout doesn't come out of the sky like a gas and seep into everything. It can best be described as a fine to coarse sand carried by the winds.

Because the wind direction varies at different heights above the ground, it is not possible to judge from the ground where the fallout will settle. It can settle in irregular patterns hundreds of miles from the explosion.

The fallout from a 5-megaton explosion could affect seriously an area of 7,000 square miles. If nothing were done to gain protection during the period of high radioactivity, there would be a grave danger to life in that area. Because fallout is carried so far and covers such a large area, it is the greatest danger after a nuclear explosion.