A Comparative Analysis of Some of the Immediate Environmental Effects at Hiroshima and Nagasaki

The problem areas of concern to those who would establish a quantitative relation between biologic response and the more immediate environmental variations caused by nuclear explosions were defined. The scope of blast and shock biology was set forth and a selective summary of current knowledge regarding biological blast effects was presented. Tentative criteria useful in assessing the hazards of some of the major nuclear effects were noted. Following elucidation of the range-yield-effects relationship applicable to high-yield explosions generally, the criteria were applied specifically to a 20-kt yield burst at heights assumed to apply to the Hiroshima and Nagasaki explosions. The procedure, establishing the range-effect relationships for the two Japanese cities, was carried out through use of the free-field scaling laws and a mathematical model allowing scaling of translational effects for both debris and man. Thus an attempt was made to predict the ranges inside which the potential existed for producing specified levels of biological damage. For each of the predicted ranges, values for overpressure, thermal and initial nuclear radiations along with translational velocities for man and glass fragments were computed to allow a more balanced appreciation of all the effects parameters that pose a hazard to man. The implications of the free-field range-effects data in interpreting some of the immediate effects at Hiroshima and Nagasaki were explored and discussed. Though the over-all analytical approach followed was thought to be useful and sound, the tentative nature of many of the numerical data presented was emphasized. Thus those numbers employed representing best current estimates as well as values arbitrarily assigned were all noted to be subject to future refinement as new information expands the understanding of nuclear phenomenology and the consequences of exposure thereto.