The Marshallese who were exposed have been categorized into three groups byatoll. The majority was located on Utirik Atoll (Utirik) and was evacuated to Kwajalein between 55 and 78 hours after detonation. The next largest group was located on Rongelap Atoll (Rongelap), this group was evacuated to Kwajalein at about 50 hours post-detonation. The third largest group was on Ailingnae Atoll (Ailingnae), and was evacuated to Kwajalein at about 58 hours post-detonation. Themajority of the Marshallese was mostly outdoors and unprotected by clothing or shoes during the passage of the fall-out plume over otheratolls; thus their skin was exposed to substantial quantities of fall-out materials. 4.2.2 Types of Acute Exposures The radiation exposures of these individuals comprised combinations of (1) external exposure to the whole-body and skin from materials in the cloud and fall-out, (2) external exposure to the skin from fall-out materials deposited on exposed surfaces of the body, and (3) internal exposure of the body organs to radiation from inhaled or ingested fall-out materials. All these individuals were exposed externally to the external radiation from activity in the plume. According to survey meter measurements (with varying degrees of certainty), the populations of the four atolls (Rongerik, Rongelap, Ailingnae, and Utirik) "were exposed to levels of radiation that varied according to their proximity to the path of the plume,their activities and evacuation time. The quantitative estimates of these exposures are discussed later in this section. Radiation doses to skin from external contamination, and probably also internally from inhaled or ingested radionuclides, were considerably greater among the Marshallese on Rongelap, Ailingnae, and Utirik than the among the U.S. servicemen on Rongerik. Unlike the servicemen, the Marshallese were unaware of the potential hazards ofthe fall-out materials. While the servicemen were covered by clothing and shoes, took shelter and were careful to consume uncontaminated food and water, the Marshallese were not so protected. Several individuals who spent time in the ocean managed to wash off some of the contamination from their feet and other parts of their bodies. When indoors, these people were typically inside houses constructed of palms and other natural materials that offered very little shielding. The clinical symptoms and signs reported for the exposed groups were generally consistent with JU EY a 16