If the U.S. should be attacked, the people who happened to be close to a nuclear, explosion--in the area of heavy destruction--probably would be killed or seriously injured by the blast, or by the heat of the nuclear fireball.
People a few miles away--in the "fringe area" of the explosion--would be endangered by the blast and heat, and by fires that the explosion might start. However, it is likely that most of the people in the fringe area would survive these hazards.
People who were outside the fringe area would not be affected by the blast, heat or fire. Department of Defense studies show that in any nuclear attack an enemy might launch against us, tens of millions of Americans would be outside the fringe areas. To them--and to people in the fringe areas who survived the blast, heat and fire--radioactive fallout would be the main danger. Protective measures against this danger can be taken.
What Is Fallout?
When a nuclear weapon explodes near the ground, great quantities of pulverized earth and other debris are sucked up into the nuclear cloud. There the radioactive gases produced by the explosion condense on and into this debris, producing radioactive fallout particles. Within a short time, these particles fall back to earth--the larger ones first, the smaller ones later. On the way down, and after they reach the ground, the radioactive particles give off invisible gamma rays--like X-rays--too much of which can kill or injure people. These particles give off most of their radiation quickly; therefore the first few hours or days after an attack would be the most dangerous period.
