should expect to find complete destruction of buildings except those which are specially constructed. Out to the 5-pounds-per-square-inch line and perhaps somewhat beyond in the event of megaton bursts we should expect to find wooden and brick homes destroyed. Aboveground tanks and commercial and communications facilities will be severely damaged in the 5- to 10-pounds-per-square-inch range.

Underground pipelines are quite well protected; however, the service connections are usually inflexible, and breaks can be expected to occur in profusion at the points where service lines enter buildings. Severe blast damage to automobiles occurs in the 5- to 7-pounds-persquare-inch range.

FIRE DAMAGE

Superimposed upon the blast damage or compounding it will be damage from fires. Under certain conditions small fires become mass fires which consume all combustible material. The annual fire loss exceeds $1 billion now when conditions permit fires to be fought with skill; the prospects in wartime give cause for deep concern.

PROTECTIVE DESIGN FEATURES IN CONSTRUCTION

I have a few observations pertaining to protection in a general way. If there is to be a nationwide effort, then the knowledge and skills present in cities and towns all across the Nation must be applied. There are data ready for practical applications in the hands of the professional people in architect's and engineer's offices, safety engineers, building developers, city engineering offices, and others who work in materials and design. They are the same people who are responsible for the engineering and design of physical structures today.

These data say, for example, that it is possible to design a one story wood rambler house which will provide as much shelter in the basement against fallout as we now find in a conventional two-story house. By substituting a concrete floor slab 6 to 8 inches thick with a 1/4-inch hardwood finished floor glued to it, for the usual wood beam construction, we may achieve a result equally pleasing in appearance to the homeowner, yet it improves considerably the protection against fallout. The windows in basements can be eliminated; we put them there before we had electricity to light and ventilate basements. We can use smooth roofs which will not hold the fallout particles. And we can exercise more care in using brittle, friable materials which convert under low pressure to damaging missiles.

INDIVIDUAL RESPONSIBILITY

It is necessary that the individual citizen evaluate for himself the kind and degree of protection best suited to his needs. As a very important first step he should be able to estimate what he has to start with, that is, to evaluate the protection available to him in his home, office, or factory and to exercise his judgment on the risk he is taking and to know how to reduce the risk and thereby improve his chances of survival.

A FAMILY AND HOME 25 MILES FROM A TARGET

Let us assume that a man lives about 25 miles from an important, somewhat isolated strategic target; that is, there is no other important target nearby. From a 20-megaton bomb, depending on the wind direction, and height of burst, this man could reasonably expect fallout dose rates upward of 3,000 roentgens per hour at early times, blast pressure of about 1 pound per square inch, and thermal radiation of about 8 calories per square centimeter. There would be no prompt radiation problems.

What does all this add up to in terms of the total hazard to the man and his family?

Prolonged exposure without protection from residual radiation, having an R+1 hour dose rate of 3,000 roentgens per hour would give an estimated infinity dose of about 19,800 roentgens; unprotected personnel would receive a lethal dose in less than an hour, or about 10,000 roentgens in 2 weeks. The 1-pound-per-square-inch blast pressure would shatter ordinary windows and doors and superficially damage other parts of a dwelling. The thermal injury to anyone who is unprotected, that is unshielded, would be characterized by second degree burns and, very likely, eye injury if he happened to be facing the explosion.

Survival depends on how much this man has found out about weapons effects, about the precaution he needs to take, and above all what he has actually done. For instance, a shelter with a shielding factor of 100 makes the radiation tolerable. Because of the slower rate of delivery of thermal energy from the high yield weapons, he can reduce effectively the number of calories hitting him if he ducks behind something opaque. After a few seconds the bulk of the thermal energy will have been emitted and he then has about 2 minutes to get to a place where he'll be safe from flying glass and other missiles created by the blast wave which travels at the speed of sound. Depending on the meteorological conditions, of course, the fallout could be expected to arrive in around 20 minutes to an hour and continue to fall for about 2 to 6 hours. Thus it can be seen that the effects of a detonation of 20 megatons as experienced at 25 miles do not confront our man simultaneously. If he knows the sequence of events, and if he knows what he has to do to survive, he has time to act. He does have to act correctly the first time or take the conquences.

At such distances few knowledgeable, intelligent people need be hurt seriously.

COST OF PROTECTION

I mentioned some examples of the protection we can undertake as we go along with new construction and new planning. Encouragement, perhaps insistence, is needed to stimulate practical applications while plans are still on the drawing boards Almost every time I talk about a shelter, the first question is: "How much does it cost?" People do not ask right away such questions as: "How close to the ground zero will the shelter protect my family?" or "Is a shelter really neces sary?" or "What do I need in addition to the structure?"

Once you have settled on the type of shelter that the local situation requires once you have settled on the protection that the shelter

has to furnish-then is the time to get around to the costs of the different ways of getting the protection. But we cannot go by the cost alone.

Ten years ago and more there were protective measures which would improve one's chances of survival. The threat has multiplied, yet, if we do some things, we can still expect to keep the number of casualties down. Knowledge, practical applications, shelters, instruments, and good local organization are the basic components. With these and a resolute spirit the combined defenses will improve.

Mr. HOLIFIELD. Thank you very much, Mr. Corsbie, for this very fine presentation. This is going to be very valuable in helping us prepare our report.

Mr. Roback has some questions.

NATIONAL COMMITTEE FOR RADIATION PROTECTION

Mr. ROBACK. I would like to ask Dr. Dunham whether he is familiar with the report of the National Committee for Radiation Protection?

Are you familiar with that report, Dr. Dunham?

Dr. DUNHAM. I assume, Mr Roback, you are talking about the one still in preparation which has to do with civil defense and was being developed at the request of the FCDA at the time the request was made?

Mr. ROBACK. Yes. Are you familiar with the findings in the report?

Dr. DUNHAM. I haven't seen a copy of it for some months. I think it is going through its final stages. As I recall, the purpose of the report is to try to give a feel for the amount of radiation exposure which people could tolerate. And it is a sort of general discussion of radiation. It doesn't get into the sort of thing that Mr. Corsbie presented, which is how much radiation is likely to occur at a specific distance from a specific type of weapon.

Mr. ROBACK. Well, in peacetime for industrial purposes, this committee tried to set up some dosage limits or criteria

Dr. DUNHAM. This is the other subcommittee.

Mr. ROBACK. I understand.

But this is an effort to do the same for wartime effects.

Now, do they come up with some specific criteria, or do they just admonish civil defense planners to keep down as much as possible the level of radiation received?

Dr. DUNHAM. I think they go a little further. Their basic philosophy is, don't take unnecessary exposure just because there is a war going on. But what they try to point out is that if you are a civil defense worker and deliberately take several hundred r, you may be a sick man and no use to the civil defense organization a couple of weeks later, and you had better try to keep it down as low as you can and not waste your radiation exposure, or your tolerance of radiation the first couple of days.

Mr. ROBACK. Does the Atomic Energy Commission act to review that report?

Dr. DUNHAM. I have reviewed it and commented on it. And I think Dr. Dunning also has had a chance to comment on it, and Dr.

Western. There are several people in the AEC who have commented on the report.

ACCURACY OF RADIATION MONITORING

Mr. ROBACK. One of the points in the report, I understand, has to do with the large margin of error in the kind of measuring instruments that might be available either to individuals or to monitoring agencies. The margin of error might be plus or minus 25, 35, or even 50 percent. Now, from a medical standpoint that might make quite a difference. Do you have any commentary on the state of the measuring instrument art, and on the findings of this national committee in that respect?

Dr. DUNHAM. I think that with most of the devices that would be available under these circumstances you would have to expect at least a 25 to 50 percent margin of error, because the individual is seldom in the same spot as the device is.

As far as the medical treatment of people goes, you don't treat by the measurements, you treat the symptoms as they appear, because people vary very greatly. One person receiving 200 roentgens will have no symptoms whatsoever, and the next person, if he is a person who, for reasons we don't understand, has an increased susceptibility, may go through the whole business of acute radiation body injury. So one must not rely on those readings except as very crude guides as to who is likely to have trouble and who isn't.

Mr. ROBACK. They are very crude guides, but from the standpoint of planning you have to look to the measurements rather than the symptoms, because you are trying to avoid the symptoms, or the things that cause symptoms.

Dr. DUNHAM. That is correct.

ALLOWING 200 ROENTGENS DOSE FOR CIVIL DEFENSE WORKERS

Mr. ROBACK. Now, in the light of the 200 roentgens standard which has been cited by the Office of Civil and Defense Mobilization as a kind of a top limit that one should be concerned about, if you had instruments with plus or minus 50 percent error, then 200 could become 400 for a sizable part of the population, and it runs you into trouble.

Dr. DUNHAM. That would run it up to 300, wouldn't it, rather than 400, plus or minus 50?

Mr. ROBACK. Or even 300?

Dr. DUNHAM. But that would be in the range of individuals variation, so I don't think you lose too much.

Mr. ROBACK. Do you think the 200 figure is a pretty good working figure?

Dr. DUNHAM. If you keep below that, you will have very few people who will be casualties from radiation.

Mr. ROBACK. There is a good deal of emphasis in civil defense exhortations to the public, and in some of their planning or guide documents, on immediate protection without trying to examine the different phases, you might say, of civil defense effort in terms of being in shelters, emerging, having specified rescue operations or recovery operations. Would it make any sense from a medical standpoint, to try to set up standards within that 200 roentgens limitation for different phases of civil defense, as, for example, in the acute or initial phase,

in some kind of an interim phase, perhaps, and then the recovery phase, should we try to assign roentgen's to each phase?

Dr. DUNHAM. I would like to comment this way. If you can spread your 200 roentgens exposure over a period of weeks, as Mr. Holifield pointed out earlier, then you are in a much safer ballpark than if you allow it to happen all of a sudden or in matter of 2 or 3 days.

This point that Mr. Corsbie touched on earlier, a factor of a hundred in terms of attenuation of fallout radiation in a shelter, really is a remarkably effective factor.

I believe some of the studies have indicated that in an ordinary brick house with a reasonable bit of shelter built in the basement you can get a protection factor somewhere between 100 and 200. This would require a 20,000 roentgens infite dose to 100 or 200 roentgens, which puts you right in the range where survival without any serious illness would be most likely.

Mr. ROBACK. But if you soak it all up when you are sitting under cover, you couldn't have much to go on if you are assigned to emerge for monitoring purposes or to obtain food or whatever the task is, assuming this is a group effort.

Dr. DUNHAM. I think we are going to have to take some casualties in the civil defense personnel, just like you always do with your firefighters in peacetime.

Some people are going to exceed the dose of radiation that will make them sick, there is bound to be some of that. You can't plan the dose precisely under an emergency situation. But with good emergency communications with people in the shelters and instrumentation indicating to them what the general levels are, then they can be given some guidance as to how long they can go out without accumulating another 10 to 15 roentgens. And this sort of thing can be extremely useful.

But, as far as going in and getting some supplies from some place that is very hot, I am afraid there will be some sacrifices. It is just the nature of war.

RADIATION DECAY RATE

Mr. ROBACK. Keeping in mind some technical controversy over the decay rates of radiation, will you comment on the longer term radiation hazards of nuclear attack?

Dr. DUNHAM. Well, the longer term hazards are the things I touched on in my testimony, which are essentially those beginning 4 or 5 years later. There is an increased incidence of leukemia among people who have had a hundred roentgens or more but it would be a relatively small fraction of those so exposed.

Mr. ROBACK. I am thinking, Dr. Dunham, from the standpoint of these differing formulas or relationships

Dr. DUNHAM. You mean the t-1.2 proposition?

Mr. ROBACK. Yes. Say after a year, between 1 and 10 years after the attack, what does the radiation environment look like?

In the t-1.2 formula it looks a lot worse than others. So someone might be a lot concerned about the long-term hazard, depending on how they figured it.

Dr. DUNHAM. It is my understanding that this is primarily concerned with the exposure that would take place shortly after the deto