EXTERNAL =X/OSURE A value of .73 Rads in tissue of interest per Roentgen measured in air at one meter above the surface was used to convert exposure in air to absorbed dose in tissue. The source was assumed to be an exponential distribution of 137¢6 acy tivity with depth in soil, typical of aged fallout (Be70). Because of the multidirectional nature of the source, variation of absorbed dose with depth of organ was minimal. Additionally, external doses were adjusted for living pat- tern variutions since the atolls present a heterogeneous exposure rate environ- ment (Gr77). External exposure calculations are based on figures 24, 25 and 26 which were derived from data listed in Cr56, Sh57, Un59, and Gr77. The area under straight line portions of the curve was determined by ye tee , ntl (6) where X = external exposure during straight line interval, oR, Ry = exposure rate at the end of the interval, mRh-, Ry = exposure rate at the beginning of the interval, kh, to = time ; osc detonation at the end of interval, hours, ty = tiwe ;os2 detonation at the beginning 22 interval, hours, n slope = Data fr.». uean tal Utiril:, of a straight line. 1! detonations during May, June and July of 1958 (Sh57) indicated a out deposition exponent of 18.%. This mean value was observed at Kon; -lap, Parry and Wotho and applied to early time post detonation of 23