Fallout risk following a major nuclear attack on the United States

Fallout distributions are calculated for nuclear attacks on the contiguous United States. Four attack scenarios are treated, including counterforce and counterforce-countervalue attacks, for meteorological conditions associated with a typical day in summer and one in winter. The countervalue attacks contain mostly airbursts. To determine fallout effects, the population surviving the prompt effects is first calculated. For the prompt effects, a "conflagration-type" model is used. The counterforce attack produces about 8 million prompt deaths, and the counterforce-countervalue case projects 98 million prompt deaths. Partial relocation before attack to low-risk fallout areas at least 15 km from potential strategic targets would result in a decrease in projections of deaths by tens of millions. For fallout risk calculations, only the dose received in the first 48 h (the early or local fallout) is considered. Populations are assumed to be sheltered, with a shelter protection factor profile that varies for a large urban area, a small urban area, or a rural area. With these profiles, without relocation, the fallout fatalities for all four attack scenarios are calculated to be less than one million people. This can be compared to fallout fatalities of about 10 million for a hypothetical unsheltered "phantom" population.