teken, Thus, by necessity, the most practical criteria upen which to base « decision are gamma dose rate readings, which are in turn related to the amount of fallout. Dose The most immediate solution aight be to establish lower pernitted dose rate levels et leter times after detonation. Hovever, if a series of Gose rates are established for increasing times after detonation se that their relationship follovs t72°*, then the doses delivered in X hours (before the material is washed off) will be grester for earlier tines after detonation. If one were sure of the tine that the fallout saterial waz to remain in place, then a scale ef dose rates versus time after detonation could be made to yield the same total dose over the X hours. Since there is obviously no set time period for duration of contest that would be valid for all cases, one might assume the worst case where the aaterial remains in place until its activity has decayed to an insignificant level, Dose rates could then be approximated, to yield a given infinity‘dove, by: De 54st where: D ® infinity dose A # dose rate at tine “t", If the above discussion is accepted, then the remaining question is to set the infinity dose, Here, we must be cleer that whereas the measurements taken by the monitors, and the data upon which action will be decided will be gamma dose rate readings, the point of principal concern is the beta dose delivered to the basal layer of the epidermis (essuzed ac 7 milligrams per square centineter). The retio of emission of beta to gama is a function of . Pear Me ig ee deh ee IS