Radiation and Blast

      WHILE MANY OF THE PRINCIPLES stated in this article  apply to industrial explosion or blast From high explosive bombs, the distinctive features of the
discussion in these blog will concern atomic or nuclear explosions. Before considering the effects of such explosions on human beings it will be well to review briefly some Of the facts that a person should bear in mind concerning atomic attacks.
        An atomic explosion causes a brilliant flash, the entire sky  being lit up very brightly. Upon observing the sudden flash of light do not look towards the centre of the flash, because the "ball of fire"that is produced by the explosion remains vivid for ten or mote seconds after the explosion, and the light from it may injure the eyes. Also for more than a minute after the  explosion dangerous short waves known as gamma rays are produced. About half of the total gamma radiation is emitted within the first second, 80 per cent within 10 seconds and all that is of impotance within a couple of minutes. Thus a person has a little time during which to seek further shelter such as behind wall ot in a trench to escape some of the gamma radiation. In doing this he may save his life. The heat waves that are
produced by the explosion are the main cause of burns, and they are almost all produced within the first three seconds after the beginning of the explosion. These waves are not so penetrating as the gamma waves, and although the time period is short, a person can escape a portion of the heat wave if he immediately falls down with his head and hands and any other unclothed part on the side away from the bomb. Ultra-violet rays are also produced, but they do not appear to be the main factor in producing burns. According to the American Red Cross, if protection can be found within two seconds after the flash of light appears, one-third of the heat radiation can be avoided.
         When a bomb explodes, it heats the air about it. That heated air expands rapidly and causes a crushing pressure wave extending outward. The increase of atmospheric pressure is greatest near the bomb and decreases with the distance.
The essential features of the shock waves from an atomic explosion are an abrupt rise in pressure, followed by a gradually decreasing pressure which lasts about a second. Then comes a suction phase which is characterized by very low atmospheric pressure lasting a few seconds. Associated with the abrupt rise in pressure during the first phase of the blast wave is an intense wind that persists with decreasing velocity throughout the pressure phase. The wind reverses its direction at
the start of the suction phase, blowing with much lower velocity but persisting slightly longer.
         Two factors operate to destroy a building ; the crushing effect of the pressure, and the speed with which the pressure changes. The pressure front does not travel nearly as rapidly
as gamma rays, ultraviolet light and heat radiation, all of which go with the speed of light. About five seconds after detonation the pressure front would reach points a mile away.
         An atomic bomb explosion is likely to cause fires. The heat waves that cause burn casualties may also cause fires by raising  the temperature of combustible objects above their kindling points. But the blast wave which comes later usually puts out
most of these fires. This is due to the fact that the heat waves raise the temperature for only a brief time. It seems that most of
the fires in connection with atomic explosions have been caused by overturned stoves, furnaces, and broken electrical circuits. These little fires, if not controlled, may grow into quite a conflagration. Experience, however, shows that a great fire does not develop for half an hour or more after the explosion.

Residual Radiation

    Fission products and bomb material yield substances some which are radioactive. Also certain particles emitted may produce radioactivity in materials that they strike. In an atomic explosion where  the bomb is burst high in the air as it was in Hiroshima, the residual radiation is insignificant. However, in cases of ground or underwater bursts, this would be a hazard in
some areas. The importance of that hazard would vary according to the length of time a person is exposed to it and the amount of radioactivity present in the area of the exposure.
        If the bomb is exploded under water, blast will be decreased and burn effects will almost be absent. However, the spray that will be thrown up will cause an immediate
residual radiation of varying amounts over the area where it falls, and the surge of waters the mist caused by the explosion - will spread out and may contaminate the near by land and the body of water with radioactive materials. This mist will
be dangerous to people in the area.
          In an explosion on the ground, or one that occurs near the surface, blast and burn effects will be decreased as compared
with the high elevation explosion discussed earlier. The immediate radiation of a ground explosion will have a decreased
range, but there will be much more residual radiation. In any case, a large amount of dust particles will be picked up ; these particles will become associated with radioactive material that will produce '"fallout"on the down wind side and should be considered dangerous.
         All the world was shocked in 1945 by the thousands killed in Hiroshima and Nagasaki by atom bombs. The number of
dead and injured could have been greatly lessened if the Japanese could have known what to expect and how to care for
themselves in such a disaster. The world has entered what is known as the atomic era. Many of the weapons of modern
[next] warfare are nuclear and are damaging not only to military personnel but to the general public as well. We pray that none of those who read this article will ever have to make use of the instructionsin this article , but in view of the situation that exists today it is felt that preparedness on the part of all is necessary.

what to Do when there is Radiation and blast?

          In the event Of an atomic attack, self-help is fundamental. This means that everyone must be willing and able to help himself and hisneighbours. Everyone must recognize that in a great emergency those who have had training will have the best chance of survival.
        Following a bomb attack you must recognize that you may need to share your house with strangers or you may be one of
those seeking or finding shelter where only the barest necessities are available. In emergency situations, the behaviour of individuals is unpredictable. Some make themselves useful immediately and respond to the situation with courage. Others become confused and frightened into panic, or lapse into apathy or helplessness.
          In any disaster be courageous and resourceful. Obviously there is bound to be a degree of confusion.. Do your part to  help meet the situation, and use your very best judgment. It has been amply demonstrated that a few people setting a courageous
example serve as an inspiration and as a steadying influence upon all around them.
          As you set an example of competence and resourcefulness you can help those around you in many ways. Point out to the
people that the force of the disaster has passed. Nothing can be gained by fright. Remind them that the resources of the nation or the community will be mobilized to help ; that shelters, food and medical care will be provided ; that means of communication will be established ; that a Missing Persons' Bureau will function,
and that'it is best to remain in or near the home if it is not in the radiation area. Also you can give the people something to do
that will help them with their immediate problem. It is well recognized that having something worth while to do is a very
good way to raise morale.
         Ordinarily after high explosive bomb attacks there will be what we called"islands of destruction,"that is, areas of great devastation in which the high explosive bombs have been exploded. In case of atomic bomb explosion there is a central area of almost complete devastation and farther out the destruction gradually decreases until the outer fringe is reached, beyond which the destructive force of the bomb has not been felt.
        In the case of industrial explosions such as may occur at powder factories
or refineries or in certain other types of
industrial areas, the blast would be very similar in effect to that of a high explosive bomb.
        In the central area of devastation there probably would be few survivors, and it would be very difficult to reach those who
may have survived. The roads would very likely be blocked and the living victims would very probably be trapped or covered by debris. Farther out, of course, in a band of severe destruction it would be possible for rescue workers to do their most eftective work. Squads should be organized and sent into this area to determine systematically where the casualties are, to rescue them and give them the necessary first aid. This, of course,would be a very difficult task for the squad members, but it is here that probably the greatest amount of good could be accomplished, as the task would be to rescue as well as to give first aid.
        During an emergency the kinds of food available may be drastically limited, but as nourishment is always important for
the sick and the injured, they should be given every consideration in such a time of need. Also the dangers of food borne
diseases and the possibility of food contamination by radioactivity must be considered.
        Let us take for example, a situation in which your home is located four miles from an atomic bomb explosion. The blast
wave breaks the windows in your home and knocks the plaster off the walls and may blow the tiles of f the roof. As a result your child sustains a cut on the arm. You control the bleeding and apply a sterile dressing. It would be unwise to go several miles with the child to a crowded medical station at once. It will
probably be better to wait until the next day when there would be less waiting in line and less confusion and more time for
attention. After such an explosion first-aid stations will be in operation for many days at selected points for dealing with
patients who do not require hospitalization. By that time doctors and nurses would have beam brought from distant points for help, as is always done in major disasters.



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