Nuclear weapons: fallout levels after 24 hours by distance

Alongside the initial blast of a nuclear explosion, and the large burst of thermal radiation, the third effect of a nuclear explosion is nuclear radiation. Nuclear weapons may be detonated in the air (known as an "air burst" explosion), which causes a much larger blast radius, or they may be detonated at ground level, which has a smaller overall blast radius but causes more destruction at ground zero. A major difference between the two is that a ground level explosion results in more radioactive debris, dust, and ash being thrown into the air - nuclear blasts cause a collapse of air pressure at their epicenter, which then funnels this material straight upwards into the sky, before it then spreads out in the form of a mushroom cloud. These clouds may take around ten minutes to reach their maximum height, and may remain in the sky for over an hour, before the material, known as "fallout", then falls back to the surface.

Variables

The figures shown are for a very specific and hypothetical nuclear attack, with fairly unrealistic weather patterns. In practice, the effects and intensity of nuclear radiation on wider populations would vary wildly. Radiation levels would first be subject to the strength of the bomb and the environment that was attacked, which would determine the amount of fallout sent into the sky and the height at which it falls from. Thereafter, environmental factors such as precipitation, air pressure, humidity, and wind would determine the area of impact, with wind alone determining distance and direction of this area. Finally, not all of the people affected by the explosion would experience the same effects, with exposure levels fluctuating based on the time spent in the area, or the thickness and material of walls between the person and the environment, or individual health, to name but a few.

Effects of nuclear radiation

At high doses, where exposure exceeds 2,000 rads or more, those not killed by the blast or extreme temperatures would likely die within 2-3 hours due to the effect of radiation on their central nervous system, which would immediately disorientate and incapacitate those affected, causing convulsions, shock, and comas. At lower levels of around 500-2,000 rads, the effects would be more severe on the digestive system - most would die within 7-10 days, as radiation sickness would destroy the lining of the intestines, causing severe diarrhea, internal bleeding, and infection. For those exposed to somewhere between 100-500 rads, the effects are still severe on the digestive system as well as in the bone marrow - some may die within 2-3 weeks of exposure, while others may survive for another one or two years. Those exposed to around 100 rads have a relatively low risk of dying, but will likely feel radiation sickness after 48 hours of exposure - radiation sickness has a variety of side effects such as milder cases of the aforementioned symptoms, as well as anorexia, cramps, fatigue, fever, listlessness, and headaches.