# at teken, Thus, by necessity, the most practical criteria upen viiieh to bese a decision are gamma dese rate readings, which are in turn related te the smount of fallout. Doss The nost immediate solution might be te establish lover permittod dose rate levels at later tines after detenation. Hovever, if a series of dose rates are established for increasing times after detonation se that their relationship follovs t~!**, then the doses delivered in I hours (before the materia] is washed off) will ve greater for earlier tines after detonation. If one were sure of the tise that the fallout material was to remain in place, then a scale of dose rates versus tine after detonation eould be made to yield the same total dose over the X hours. Since there is obviously no set time period for duration of eontast that would be valid for all eases, one might assume the worst case where the saterial remains in place until its ectivity has decayed to an insignificant level. Dose rates @ould then be approximated, to yield a given infinitydone, by: Dew 5st where: 0D infinity dose A ® dose rate at time “t*, If the above discussion is aceepted, then the remaining question is to set the infinity dose. Here, we must be clear that whereas the peasurements 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 (assumed ac 7 milligrams per square centineter). The ratio of emission ef beta tc gama is a function ef ue aw A Pee ‘~ ™ ' =D Wek Lay 0 im