a| of course, the fallout material may be removed before the infinity dose is delivered; yet, on the other hand, it is net improbable that it could remain in the hair for essentially this length sf time. In the case of a one-hour fallout, almost one half of the dose would be delivered in the next 24 hours. | The efficiency of a surface for collecting and holding the fallout material is important. It is not surprising that the highest dose rate readings as well as biological effects were noted on the hair of the natives and also on parts of the exposed body where perspiration was present. Further, it was observed that even one layer of light cotton material was sufficient to protect against beta skin damage in most cases®*. This was due probably not to the relatively small attenuation of the betas by the clothing but rather to the physical situation of holding the radioactive material at some distance from the skin, which effect would be relatively large. An added consideration is the possibility of high beta doses delivered to personnel from the fallout material lying on the ground end other surfaces. If the highest degree of contamination considered Rey e-em under this policy is safe when in direct contact with the skin, then the beta dose from an equally contaminated ground will not be hazardous. (See Criteria III for discussion on unequal contamination on personnel.) However, it is true that the contamination may exceed the amount to deliver dose rates given in graph I] and yet not be great enough to consider evacuation. Some personnel may not go indoors and those who did will eventually be released from this restrictive action and then may walk around in a relatively highly contaminated area. Because of the more limited range of the beta, the location of greatest concern *ITR=923. Study of Response of Human Beings AccidentallyExposed FalloutRaditon, Cronkite, E. P., et al. May 1954.