(one. Ea The rationale for table Ia is as follows: ‘The total effective tiolorical Gose that would be received if evacuation were not ordered is obviously & determining factor, Another consideration is the fact that such an action &@s evacuation could be danrerous to the individuals and could also possibly be detrimental to a very neceszary national effort of weapons development. One must then ask, “Just how mmch will be gained (radiation dose saved) by wvacustion?® Estimates of these two varistles are indicated in table Ia, Thus, @ populace may receive up to # calculated 30 roentgen effective biological | dose in one year without indicating evacuation; from 30 to 50 roentgens, evacuation would be considered only if at least 15 roentgens could be saved by svch action; and at 50 roentgens or hicher evacuation would be indicated without regard to the possible savings in radiation dose, In making a rough estimate of radiation doses, one may calculate a theoretical maximus inf!nity gamma dose and then arsitrartly divide by some rumber suc’, as "2" for an esticate of dose actually received, Whereas this may be satisfactory as e first approximation, s more realistic estimate should be made, eepecially wen dealizg with doses that misnt constitute a health hasard, Due to the necessity of making early peasurerents and decisions, it is to be expected that dose-rate readicgs, taken with survey meters, will be the available evidence at the times of concers. Table Ib surmarises the paraactars considered in estimating an effective biological dose based on dose-rate a readings, \ Sarees oT