How Far Does the "Fall Out" From a Nuclear Bomb Travel? ( And Related Data )

How far the "fall-out" travels depends upon the size of the bomb..In
the movie " Threads" it said
300 miles...I think they meant 300 square miles....

detonations in the atmosphere if the fireball rises into the
stratosphere. In this case, the high temperatures of the fireball
destroy ozone and create various oxides of nitrogen. For large numbers
(hundreds or thousands) of high yield detonations, these changes can
exceed natural variations. Such depletion of ozone would increase
solar ultraviolet reaching the Earth's surface. Nitrogen oxides tend
to produce a global cooling effect. Both consequences would return to
normal over periods of years.

The following summary of effects is based on a 20-megaton ground-burst
nuclear detonation above a city with a population of 2.8 million
during the day when many people from outlying areas would be in the
city working or shopping.
Ground Zero to Two Miles
Within 1/1000th of a second, a fireball would form, enveloping
downtown and reaching out for two miles in every direction from the
point where the bomb went off, commonly known as ground zero.
Temperatures would rise to 20 million degrees Fahrenheit, and
everything-- buildings, trees, cars, and people--would be vaporized.
Two Miles to Four Miles from Ground Zero:
Out to a distance of 4 miles, the blast would produce pressures of 25
pounds per square inch and winds in excess of 650 miles per hour.
These titanic forces would rip buildings apart and level everything,
including reinforced concrete and steel structures. Even deep
underground bomb shelters would be crushed.
Four Miles to Ten Miles from Ground Zero:
As far as six miles from the center of the explosion, the heat would
vaporize automobile sheet metal. Glass would melt. Out to a distance
of ten miles in all directions, the heat would still be intense enough
to melt sheet metal. At this distance, the blast wave would create
pressures of 7 to 10 pounds per square inch and winds of 200 miles per
hour. Reinforced concrete buildings would be heavily damaged and all
other buildings--masonry and wood frame--would be leveled.
Sixteen Miles from Ground Zero:
At a distance of 16 miles from the center, the heat would ignite all
easily flammable materials (houses, paper, cloth, leaves, gasoline,
heating fuel)—and start hundreds of thousands of fires. Fanned by
blast winds still in excess of 100 miles per hour, these fires would
merge into a giant firestorm more than 30 miles across and covering
800 square miles. Flames would consume everything within this entire
area. Temperatures would rise to 1400 degrees Fahrenheit. The death
rate would approach 100%.
Firestorms of this type, though on a smaller scale, developed in
Hamburg, Dresden, and in parts of Tokyo after conventional bombing
attacks during World War II. The information gained from these
experiences has particular relevance to the question of fallout
shelters. In these earlier firestorms only those who left their bomb
shelters had any chance of surviving. Those who remained in
underground shelters were killed, roasted as their bunkers were turned
into ovens and suffocated as the fires consumed all of the oxygen in
the air.
Beyond Sixteen Miles:
At 21 miles from ground zero, the blast would still produce pressures
of two pounds per square inch, enough to shatter glass windows and
turn each of them into hundreds of lethal missiles flying outward from
the center at 100 miles per hour. At 29 miles away from the center the
heat would be so intense that all exposed skin, not protected by
clothing, would suffer third degree burns. To a distance of 32 miles
second degree burns. Even as far as 40 miles from ground zero anyone
who turned to gaze at the sudden flash of light would be blinded by
burns on the retina at the back of their eyes.
Major Injuries Caused by a Nuclear Explosion:
Within minutes after the bomb exploded 1,000,000 people would die.
Among the 1,800,000 survivors more than 1,100,000 would be fatally
injured. Another 500,000 would have major injuries from which they
might recover if they received adequate medical care. Less than
200,000 people would remain without injuries.
Burn Wounds
In the immediate post attack period, burns would constitute the most
common and serious medical problem. Hundreds of thousands of people
would have sustained major second and third degree burns, some from
the direct effects of the heat flash on exposed skin, others injured
in the thousands of fires that would rage on the periphery of the
great firestorm. These people would need urgent and intensive medical
therapy. It would not be available.
Facilities for Treating Burn Wounds
In the entire United States, there are only 2000 special beds for burn
patients. In most major metropolitan areas there are only 100 burn
beds and most of these would have been destroyed by the bomb. At best,
a tiny fraction of the hundreds of thousands of burn patients would
receive appropriate medical care. The rest would die.
Other Types of Injuries
In addition to these burn patients there would be many thousands of
other injuries. People blinded by the blast flash or deafened when the
pressure wave ruptured their ear drums. People with lungs collapsed by
the tremendous pressures. People with stab wounds of the head chest
and abdomen who had been struck by flying debris. People with bones
broken when they had been hurled through the air by the hurricane
force winds or trapped under collapsing buildings.
The Effects of Radiation Sickness
The Effects of Fall-Out
Shortly after the explosion, there would be added to this list of
casualties tens of thousands of others suffering from a unique form of
injury: radiation sickness. The precise extent of radiation injuries
would depend to a great deal on weather conditions; particularly the
direction and speed of the wind at the time of the explosion. These
factors would determine how far, and in what direction, the fallout
would spread.
Effects of High Doses of Radiation Sickness
People who were exposed to very high doses of radiation, 4000 to 5000
Rads, would suffer what is known as the central nervous system
syndrome. Their brain tissue, damaged by the radiation, would swell,
causing nausea, vomiting, explosive diarrhea, and progressive
difficulty walking talking and thinking clearly. They would develop
convulsions and pass into a coma and die, usually within the first day
or two after the bomb. Once someone had been exposed to doses in this
range, there would be no effective treatment.
Effects of Medium Doses of Radiation Sickness
People exposed to lesser doses of radiation, down to about 400 to 600
Rads, would suffer a gastrointestinal form of radiation sickness. They
would experience nausea, vomiting and diarrhea soon after exposure
which would last for several days and then seem to improve. But, after
a few days to a week, the symptoms would return and become worse. The
diarrhea and vomit would become bloody as the lining of their stomachs
and intestines, damaged by the radiation, began to shed. The majority
of these patients would also die, despite the most intensive medical
Effects of Low Doses of Radiation Sickness
People with even smaller radiation exposure, in the 100 to 300 Rad
range, would suffer from the hematologic radiation syndrome. They also
would suffer nausea, vomiting and diarrhea for a few days, but these
symptoms would resolve. About three weeks after exposure, their bone
marrow would stop producing normal numbers of blood cells. As their
white blood cell count fell, they would become prey to infection.
Sores would form in their mouths. Burns and other wounds suffered in
the initial attack would become infected and fail to heal. They would
also have a fall in the number of platelets, the cell fragments that
help blood to clot. They would hemorrhage into their skin, and new
bleeding would begin in the intestines and stomach.
Chances For Survival From Radiation Sickness
Those who had received doses in the lower end of this range would have
a very great chance of surviving if they received adequate care. Those
at the upper end of the exposure scale would have a much worse
prognosis, even if they received intensive therapy. Unfortunately it
would be impossible to tell how much radiation a given patient had
received. Except at the very highest doses, the initial symptoms would
be the same. The already overwhelming problem of caring for the
wounded would be complicated by an inability to decide who might
benefit from therapy and should receive whatever resources might be

Nations with nuclear weapons
Country Warheads active/total Year of first test
United States 5,735/9,960 1945
Russia 5,830/16,000 1949
United Kingdom 200 1952
France 350 1960
China 130 1964
India 70-120 1974
Pakistan 30-52 1998
North Korea 1-10 2006
Undeclared nuclear weapons states
Israel 75-200 none or unknown or 1979

Nuclear Winter

Fallout is a grim and long lasting feature of ground burst atomic
munitions. Essentially, fallout is the irradiated dust and debris
particles resulting from a nuclear blast. The half life of these
particles can range from an hour, to a week, to many years depending
on the intensity of the blast. All radiation is toxic in varying
degrees and doses.

The mixture of radioactive elements formed in a nuclear explosion is
so complex, with both short- and long-lasting isotopes, that
radioactive decay can only be estimated. During the first hour after a
nuclear explosion, radioactivity levels drop precipitously.
Radioactivity levels are further reduced by about 90% after another 7
hours and by about 99% after 2 days. That is for short term
radioactive material. Long term, such as Plutonium, is a different
matter. For more information, see here...

The immediate threat is direct exposure to skin from rainfall and dust
particles riding on low breezes. The result is external radiation
burns and ARS (Acute Radiation Syndrome).

Precipitation clears the irradiated particles from the air, but that
is not the end of the problem. As things dry up, normal, every day
dust is kicked up as well. Much of that will carry the contaminants.
You breath them in, they embed in your lung tissue. Depending on the
level of exposure, this can result in death from radiation poisoning
in a number of hours or days or can lead to long term health risks
such as cancer and leukemia.

The solution to the radioactive particles on the ground is by removing
the top 18 inches of soil and disposing of them in an isolated and
safe area. The definition of an "isolated and safe area" is subject to
debate, and while some suggest burying the radioactive material
underneath a mountain, others suggest disposal in the ocean (salt
water is an excellent buffer of radiation). However, these solutions
are environmentally controversial.

Note: Nuclear fallout particles will not "re-evaporate" from water
sources. They are heavier than water and will sink.