in time (recognizing that such effects from radiation as genetic changes and life shortening may not be time dependent), The estimates for biological repair for man are quite uncertain so a conservative value is used here of a half-time of repair of about four weeks. | Graph I incorporates the above factors of weathering, shielding, and biological repair into a single curve. trapolated to other dose rate readings. This graph may be linearly ex- For example, if fallout occurs | three hours after detonation and the dose rate is 10 r per hour, then about 67 r (effective biological dose) may be accumulated, i.e., ous x 1.0 = 67 CRITERIA I Effective Biologiczl Doses may be calculated according to Graph.I Table I may be used in evaluating the feasibility of evacuating rela- tively large populations. TABLE I tr te ffective Biols f+ ee cICLOGiCaAL CRITERIA FOR EVALUATING FEASIBILITY OF EVACUATION aot ct om ™ ose Minimum Effective Biological Dose That Must Be Saved By Act of Evacuation (Otherwise Evacuation Will Not Be _ Indicated) Vr tl 20 moentessrs (Me syacuction infcleated) 30 tw 50 roentgens 15 roentgens 50 roentgens and higher (Evacuation indivate. wilnont regard to auantity of dose that might os s2ved. providing adequate sieiters are not available and the estimated hazards concomitant with the evacuation are acceptable, ) - 12 - 4 = + - E Yr a Z I. = io ts ra > a. - a mp ae a ie — as © tm “a aa L 7 rt

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