person who did not find shelter within 25 minutes after the time the
fallout began. At a distance of 40-45 miles, a person would have at most 3
hours after the fallout began to find shelter. Considerably smaller
radiation doses will make people seriously ill. Thus, the survival
prospects of persons immediately downwind of the burst point would be slim
unless they could be sheltered or evacuated.

It has been estimated that an attack on U.S. population centers by 100
weapons of one-megaton fission yield would kill up to 20 percent of the
population immediately through blast, heat, ground shock and instant
radiation effects (neutrons and gamma rays); an attack with 1,000 such
weapons would destroy immediately almost half the U.S. population. These
figures do not include additional deaths from fires, lack of medical
attention, starvation, or the lethal fallout showering to the ground
downwind of the burst points of the weapons.

Most of the bomb-produced radionuclides decay rapidly. Even so, beyond the
blast radius of the exploding weapons there would be areas ("hot spots")
the survivors could not enter because of radioactive contamination from
long-lived radioactive isotopes like strontium-90 or cesium-137, which can
be concentrated through the food chain and incorporated into the body. The
damage caused would be internal, with the injurious effects appearing over
many years. For the survivors of a nuclear war, this lingering radiation
hazard could represent a grave threat for as long as 1 to 5 years after the
attack.


B. Worldwide Effects of Fallout

Much of our knowledge of the production and distribution of radionuclides