data were obtained during Operation Teapot (Spring 1955) where film badges were placed inside and outside of buildings for, several days. The ratio of out-of-doors to indoors doses ranged from 1.3 to 7 with one room frame buildings providing the least attenuation factor and multiroom concrete block buildings the greater values. This program will be expanded during Operation Plumbbob as will the program of estimating personnel exposure by having a large number of people living around the Nevada Test Site wear film badges during and following the test series. 3. Gamma energy spectra. The relative biological effectiveness of differing energy photons and their varying depth-dose curves has been shown for X-rays .12 Similar results have been obtained for gamma rays as illus- trated by one set of experimentsl3 using burros where there was a shift of LD 50/30 values (lethal dose to 50% of the exposed animals who died in 30 days) from 684 roentgens with cobalt~60 (1.25 Mev mean energy) to 585 roentgens with Zr?5 - NB92 (0.7 Mev mean energy). The gamma energy spectra from the mixture of isotopes in fallout is quite complex and is further complicated by the presence of scattered radiation, with its lesser energies, mixed with the direct radiation. Figure 5 illustrates the estimated gamma spectra at three feet above the ground following the detonation of March 1, 1954 at the Pacific Proving Ground. 4. Geometry of the source. The geometry of the source can make a significant difape —- ference in depth-dose curves and resultant biological effects. e -9- This t-