a 2 material on the islands wassufficiently intense to result in significant whole-body irradiation of the inhabitants. In addition, the skin was contaminated with the material, and someof it was inhaled and ingested. The calculated whole-body dose of radiation in roentgens as measured in air and the amountof fall-out observed for each of the island groups is shown below. The exposed American Calculated Whole Body Dose of Radiation Island Group Rongelap Allinginae Rongerik Utirik Population 64 Marshallese 18 Marshallese 28 American servicemen 157 Marshallese Whole-Body Dose in r 175 69 7 i4 Fall-Out Observed Heavy (snow-like) Moderate (mist-like) Moderate (mist-like) None servicemen were returned to duty after extensive medical examinations at Kwajalein and at the Tripler General Hospital, Honolulu, T. H. The Utirik people were returned to their native atoll after the initial period of observation. The Rongelap and Ailinginae residents were moved to Majuro Atoil for temporary occupation of dwellings built for them. These gamma ray doses were calculated from field instrument readings taken at the time of evacuation and decay schemes appropriate for the estimated times of exposure. For the sake of brevity, details will be presented only on the more severely exposed Rongelap group and the other groups will be referred to only for comparative purposes. The detonation of the device was observed in the early morning, and hours later the exposed individuals noticed a snow-like material falling from the sky; this continued for several hours. The material was visible on the ground and sifted into the lightly constructed thatched-roof houses. The material whitened the hair and clung to the skin. During the night following the explosion and for the next two days, about two-thirds of the population developed nausea and 10% vomited and had diarrhea. During this period also, many developed itching and burning of the skin and some reported burning of the eyes with lacrimation. Supervised decontamination and medicai care was not possible until the exposed individ- 2012640