Long-Term Fallout Pattern
The extent and location of radioactive fall-out will depend on weather conditions, especially the speed and direction of the wind. It should not be forgotten that fallout patterns are idealized - such neat ellipses would occur in reality only with an absolutely constant wind and no rain. The onset of fallout would depend on wind velocity and distance from the explosion and it would be most dangerous during the first few days. In the case of an attack on a single city (using a surface burst, as our example does), people living downwind would probably evacuate
Those who neither evacuated nor found adequate fallout shelters would be subjected to dangerous levels of radiation: people in the inner contour would receive a fatal dose within the first week; people in the next contour out would contract very severe radiation sickness if they stayed indoors and would probably receive a fatal dose if they spent much time outdoors; people in the next contour out would contract generally nonfatal radiation sickness, with increased hazards of deaths from other diseases. People in the outer contour (90 roentgens in the first week) would suffer few visible effects, but their life expectancy would drop as a result of an increased risk of eventual cancer.