The Medical Implications of Nuclear War (1986) / Chapter Skim
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1 Possible Fatalities from Superfires Following Nuclear Attacks in or near Urban Areas
1 Possible Fatalities from Superfires Following Nuclear Attacks in or near Urban Areas
Pages 15-72
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From page 15... ...
National Academy Press, Washington, D.C. Possible Fatalities from Superfires Following Nuclear Attacks in or near Urban Areas THEODORE A
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From page 16... ...
This methodology, which will henceforth be referred to as blast elect, or simply blast scaling, is the standard methodology used by government agencies to estimate casualties in nuclear war. The preliminary analysis presented in this paper indicates that if fire effects are included in assessments of possible fatalities from nuclear attacks using megaton or near megaton airbursts in or near urban areas, about two to four times more fatalities might be expected relative to those which might be expected from blast scaling calculations.
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From page 17... ...
Estimates of noxious gas concentrations then will be made using data presented in the previous section, and it will be shown that the combination of these toxic agents within the fire zone are likely to be lethal to all unprotected individuals. Anecdotal and medical observations from World War II firestorm experiences will be reviewed, and a very crude cookie cutter model will be discussed.
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From page 18... ...
This shell of gas, which continues to be driven outward by hot expanding gases in the fireball interior, itself compresses the surrounding air, forming a steeply fronted luminous shock wave of enormous extent and power (see Figure 1A)
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From page 19... ...
The primary and secondary shock waves then propagate outward along the ground, forming a single vertical shock wave called the reinforced Mach front (see Figure 1C)
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From page 20... ...
Nuclear and Thermal Radiation an\/ Primary Blast Wave Front Reflected Blast Wave Front Mach Front ~ Overpressure 6 psi AL = ;= _ ~3 1 Mt ~ I I ~ I I Miles 0 1 2 3 4 5 6 FIGURE 1 The sequence of events for a 1-Mt airburst detonated at 6,500 feet (about 2 km) altitude are shown in A through E
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From page 21... ...
POSSIBLE FATALITIES FROM SUPERFIRES D Rate of Rise 1 Mt 250 mob 1 MEGATON Al R BURST-37 SECONDS : Reflected Blast Wave Front _ ~ \ it, Nuclear Radiation r'''''a'Y clan \ \ , Wave Front \, of Bomb Resiclue |~ Mushroom Stem Mach Front | Overpressure 1 psi ~ Afterwinds Wind Velocity 40 mph ~ I - ~= 1 Mt r I I l ' ~ ' ~ Miles 0 1 2 3 4 5 6 7 8 9 10 l 1 Mt-Total Thermal Radiation 30 20 8 5 cal/sq cm r E Rate of Rise 1 Mt 130-170 mph Radioactive Cloud 1 MEGATON Al R BURST-1 10 SECONDS Wind Velocity 1 Mt 275 mph b~ ~AftenNinds 1 Mt r I I ~I ~ Miles 0 1 2 3 4 5 6 7 8 9 10 21 to give a 15-psi peak overpressure on the ground (see text)
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From page 22... ...
. About 16 seconds after the detonation, the shock wave arrives (D)
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From page 24... ...
Because these structures were constructed to study the effects of blast, precautions were taken to prevent them from burning. The exteriors were painted white to reflect rather than to absorb light from the fireball, windows facing the explosion were equipped with light-reflecting aluminum finish, metal Venetian blinds, and roofs were made of light gray asbestos cement shingles.
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From page 25... ...
In addition, the roofs were made of light gray asbestos shingles, and windows facing the blast were equipped with metal Venetian blinds with an aluminum finish. Source: Glasstone (1962~.6
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From page 26... ...
, and for purposes of comparison, each graph is also accompanied by a plot of the overpressure and thermal energy that occurred at Hiroshima. It should be noted that the ratio of thermal to blast effects change drastically in Figures 8 through 10, as the scales of each of these two quantities are different with changes in weapon yield.
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From page 27... ...
Hence, the range at which a given peak overpressure occurs scales as the cube root of the yield. Thermal energy, unlike blast energy, instead radiates out into the surroundings.
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From page 28... ...
, the ratio of thermal to blast effects would increase with an increase in weapon yield. Hence, weapons of higher yield are yet better incendiaries than those of lower yield.
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From page 29... ...
The building was probably subjected to a blast of about 3 psi, which did not knock it down but caused heavy interior damage. Because of the different way blast and thermal effects scale with weapon yield, the amount of thermal energy from the fireball of a 1-Mt detonation would be greater than that which occurred at the 3-psi range at Hiroshima.
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From page 30... ...
, the thermal energy at a range which results in a given overpressure is much higher than that which occurs at the same peak overpressure for the smaller detonation. Thus, the use of blast scaling alone as a method of defining the environments in which casualties may occur could potentially lead to predictions that could seriously be in error.
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From page 31... ...
Also influencing the nature and scale of mass fire dynamics is blast damage from the shock wave. The blast from the detonation would knock down some buildings and leave others standing.
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From page 32... ...
Thus, highly uncertain sources of ignition and conditions of fire spread could influence the extent of a mass fire region, its development over time, and its intensity following an airburst over or near an urban/industrial A 60 lo' 50 ·- cr 40 Q LL' `r tu 30 J 20 Al 10 > ~ 00 0 B <' 50 ._ Oc Q ~L' up Z ~ J up At: CC Cr I > ~ O O 60 40 30 20 10 o r Thermal t ~ \ ~ Blast 1~-~_ 1 1 1 1 1 1 1 0 1 2 3 4 5 6 7 8 9 10 RANGE (ml) R~: ~/ l thermal ~/m ~ Blast,:` (1 2 Kit 0 1 2 3 4 5 6 7 8 9 10 RANGE (ml)
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From page 33... ...
By comparison, the silhouette shown in the center of the diagram is the area that burned following the atomic bombing of Hiroshima. area.7 Nevertheless, as individual fires burn and intensify over a vast region, the volume of heated and buoyantly rising air from the fire zone could increase to significant levels.
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From page 34... ...
At upper altitudes, the buoyantly rising heated air from the fire zone would still create outward driving pressure differentials, and a gigantic circulating air flow would develop with winds moving outward at high altitudes and inward at low altitudes. On the ground, the resulting fire winds would begin to fan the individual fires, causing them to burn more intensely, radiating greater heat, and generating firebrands.
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From page 35... ...
Thus, predictions of ground winds and air temperatures from mass fires must consider both the scale of the fire and the heat input per unit area in the region where such fires burn.
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From page 36... ...
It is therefore possible that subtle details of weather may not be an important factor in the creation of severe ground conditions in and around a sufficiently intense mass fire. Source: Hassig and Rosenblatt (19834.8
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From page 37... ...
POSSIBLE FATaLlTIES FROM SUPERFIRES 120 100 _ 80 60 40 20 - (_ O 1 1 U.S. Standard Atmosphere Dry Adiabatic Lapse Rate Atmosphere -_ _ I I 0 50 100 150 200 2 50 300 350 Tropopause J TEMPE RATU R E ( K)
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From page 38... ...
ESTIMATES OF NOXIOUS GAS CONCENTRATIONS WITHIN THE MASS FIRE REGION The physical environments discussed in the previous sections are average environments. Actual physical conditions could differ substantially from location to location within a fire zone.
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From page 39... ...
(a) 1952 National Fire Protection Association, Quincy, Mass.
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From page 40... ...
\ ~Baseline I _ Blast Modified L ' Hamburg ol ' I I ' I ~ ~ Water Boils Room Temperature Water Freezes ~I , 0 1 2 3 4 5 6 7 RANGE (ml) 8 9 10 FIGURE 16 Calculations of average air temperatures for modeled mass fires in lightly (A)
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From page 41... ...
A detailed calculation of combustion gas concentrations therefore requires a computationally powerful simulation or hydrothermodynamic modeling techniques of the kind discussed in the previous section. However, because these techniques already provide estimates of the average air temperature and heating rates within the fire zone, they can be used to derive a very crude estimate of average gas concentrations as well.
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From page 42... ...
, the rate at which carbon monoxide (CO) might be produced is between (26 BTU/m2/s)
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From page 43... ...
Even sheltered individuals may be threatened by a similar array of toxic effects, as shelters must be carefully designed to protect occupants from the effects of infiltration of poisonous gases and from heating by fire and hot rubble.24-26 During World War II in Germany, for example, the infiltration of carbon monoxide into shelters was the apparent immediate cause of death of many in the shelters. It was further judged to be the cause of death in 70 to 80 percent of reported fatalities from large-scale incendiary raids.
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From page 44... ...
Some of the physiological effects of exposure to various levels of excessive heat, oxygen starvation, carbon monoxide, and carbon dioxide are summarized in Tables 1 through 5 and Figures 17 through 20. The Figures are derived from those published previously,22 24 28 and Tables are derived from data published previously.2228-34 It is unlikely that these toxic agents would be encountered singly in the environment of a mass fire.
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From page 45... ...
When the body carries a burden of excess heat and the air temperature is elevated, it is difficult for the body to radiate, convect, or evaporate away this excess energy to the environment. The body reacts to this circumstance by increasing its respiration and heart rate, which then results TABLE 5 Estimated Levels of Toxic Agents Causing Death in 4 Hours Variable Estimated Lethal Levels Temperature Oxygen Carbon monoxide Carbon dioxide 130°F (54°C; hyperthermia)
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From page 46... ...
Thus, even if only the effects of elevated air temperature are considered, a combination of apparently nonthreatening contingencies can still result in a serious, near certain threat to life from heat prostration or stroke. Keeping this in mind, note that exposure to air temperatures much above 130 to 140°F (54.4 to 60°C)
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From page 47... ...
It may also be accompanied by small but biologically significant concentrations of carbon monoxide, which is also formed in the process of combustion. Carbon monoxide, which is a chemical asphyxiant, is an extremely dangerous combustion product of fires (Tables 3 and 5 and Figure 19)
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From page 48... ...
(1976~.22 dioxide and elevated temperatures and its excess heat burden is further stressed by an elevated metabolic state from excitement or strenuous activity, enhanced take up of carbon monoxide by the body occurs. Furthermore, if there is carbon dioxide and other gases in the air, these gases will displace oxygen, adding still another insult of oxygen starvation to the body burden (Tables 4 and 5 and Figure 171.
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From page 49... ...
/ /.~ / ~ I twit 1 'a' -- A I 1 1 1 , , _ 02 103 104 105 106 107 108 109 SECONDS 49 600 400 300 200 100 Z cr: I LL in 7 ~111 / LL 50 o -100 FIGURE 20 The safe exposure time for humans in high-temperature environments is highly dependent on relative humidity and water consumption. It is also dependent on the level of activity, acclimatization, and body weight.
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From page 50... ...
However, at this time much additional work is required before useful insights along these lines will be available. TABLE 6 Estimated Combined Levels of Toxic Agents Causing Death in 4 Hours Toxic Agents Estimated Lethal Levels Combination of Two Carbon monoxide 0.02% CO + 120°F (49°C)
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From page 51... ...
The firestorm resulting from the second of three highly successful saturation incendiary raids at Hamburg is the most well documented to date.l 35-37 The German Fire Protection Police reports indicate that between 50,000 and 60,000 people in the fire zone were killed. At the peak of the fire's intensity, 5 to 6 mile2 (about 12.9 to 15.4 km2)
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From page 52... ...
In the second and most successful of the great raids at Hamburg, the raid of July 27 and 2S, 1943, within about 20 minutes, two of three buildings within a 4.5-mile2 (11.6-km2) area were on fire, and a major fire was in progress.35 As the individual fires grew and increased in intensity, sparks and radiated heat reached combustible interiors of nearby uninvolved buildings through shattered and undamaged windows.
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From page 53... ...
In incendiary raids over Japan, for example, B-29 pilots reported that rising columns of hot air from mass fires below could bounce the planes from 15,000 to 17,000 feet (about 4,572 to 5,182 m) in a matter of seconds.
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From page 54... ...
54 PHYSICAL EFFECTS AND ENVIRONMENTAL CONSEQUENCES FIGURE 21 A, B and C show various street scenes after the great incendiary raids at Hamburg in late July of 1943.
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From page 55... ...
The relatively ineffective German incendiary raids early in World War II alerted allied military decision makers to the potential effectiveness of incendiaries for destruction. Reprinted from Fire and the Air War.
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From page 56... ...
In some cases shelter heating may have been the cause of death, but it is believed most victims in shelters were killed by carbon monoxide poisoning. However, even if carbon monoxide poisoning could have been avoided, the heating of many shelters from overburdens of fire-heated rubble would have almost certainly killed the occupants at a later time.
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From page 57... ...
E shows corpses in a truck. These victims were probably overcome by heat and carbon monoxide as they attempted to escape a fire zone.
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From page 58... ...
However, a review of Hamburg Fire Department records37 reveals no data regarding survival in the fire zone, although documents do indicate that 18,000 people were rescued during the period from July 25 to August 4. There is a reference to the fact that hundreds of thousands of people possibly escaped the fire, presumably in its early phases, and there are additional personal reports35 of people who survived in bomb craters, in which the water table was sufficiently high that body parts could be covered with water-soaked clothing, and in public bunkers, which apparently were thick-walled, freestanding structures that were removed from the areas covered with the debris of collapsed buildings.
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From page 59... ...
The heated environment, elevated metabolic states, and the presence of carbon dioxide would induce increased respiration activity which would, in turn, increase body uptake of carbon monoxide, sulfur dioxide, nitrogen dioxide, toxic smoke, and other materials. Superheated, hurricane-force winds would do further damage to uncollapsed structures.
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From page 60... ...
* By cookie cutter it is meant that all individuals caught within the fire zone are assumed to be killed by fire effects, while all individuals outside the fire zone are assumed to survive fire effects.
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From page 61... ...
For purposes of analysis, a reference case of 100 1-Mt warheads on the 100 largest city centers in the United States is of interest. This reference case results in no overlap of areas that are subject to the effects of multiple weapons, as could be the case in many imaginable nuclear attacks; and it applies the casualty rules to circumstances similar to those from which the data were derived.
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From page 62... ...
The solid curve in A shows the assumed probability of death as a function of range from ground zero. The broken curve shows fatality data from Hiroshima scaled by assuming that the probability of death is purely a function of the peak overpressure at each range from the detonation.
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From page 63... ...
1 45 cal/cm2 1 10 cal/cm2 90 cal/cm2 20 cal/cm2 Thermal Fluence and Blast for One Megaton Air Burst FIGURE 24 Some aspects of the physical environment that could influence the probability of death at different ranges from a ground zero are compared for 1Mt and 12.5-kt detonations. The solid curve shows the probability of blast injury as a function of range from ground zero derived by applying the OTA rules to the case of a 1-Mt airburst.
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From page 64... ...
Figure 25 shows estimates of fatalities and casualties for the 100-city reference case. Blast scaling predicts that there would be 14 million to 15 million fatalities and 22 million to 23 million injured.
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From page 65... ...
A reference attack that assumes that a single 1-Mt detonation occurs over the population center of each of the 100 largest metropolitan areas is used to determine the potential significance of differing fatality and injury rules. When only blast scaling from Hiroshima is used to estimate fatalities and injures, about 14 million fatalities and 23 million injured are projected.
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From page 66... ...
It is therefore difficult to see how casualty rules that do not include the hostile effects of mass fires over such vast areas can result in projections more plausible than even those that follow from the preliminary speculations contained in this study. COMPARISON OF OTHER TARGET SETS WITH THE REFERENCE CASE Daugherty, Levi, and van Hippel44 have made a very complete and uniquely systematic study of possible fatalities and injuries from nuclear attacks against the United States.
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From page 67... ...
As shown in Figure 26, if I assume that the 100 detonations are airbursts of 1-Mt yield and that the hypothesized superfire casualty rules of the previous section apply, 25 million to 37 million deaths and 2 million to 7 million injured would result. Thus, if fires kill substantial numbers of people in target areas, the attack that does not target population per se might result in the death of between 1.5 and 2.5 times more people than the blast scaling would predict for the antipopulation attack of a similar size.
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From page 68... ...
model is still more speculative, as it is more likely that many of those who would not have been severely injured would have some chance to attempt to escape the fire region. CONCLUSION During World War II the extraordinary power of science was turned to building a weapon that could create energy densities and temperatures comparable to those that normally exist in the interiors of stars.
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From page 69... ...
the results of those and subsequent efforts have given us weapons with effects that are of vast and nonintuitive scales. One of these effects is superfires; they would accompany nuclear detonations in or near urban areas and might result in two to four times as many fatalities as that predicted by standard government blast scaling rules.
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From page 70... ...
Fire and the Air War. National Fire Protection Association.
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From page 71... ...
. 36Report of the Technical Services Division of the Hamburg Fire Protection Police During the Major Catastrophe and Summary of Reports on Actions During the Air Attacks on Hamburg from July 24 to August 3, 1943.
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From page 72... ...
Casualties Due to the Blast, Heat and Radioactive Fallout from Various Hypothetical Nuclear Attacks on the United States. This volume.
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