U 235 fission products in a local or intermediate fallout situation, As instrumentation, techniques of calibration and the predictability of the radionuclide spectrum from nuclear devices continue to improve, so will the usefulness of gamma~dose rate measure- ments for predicting the decline of gamma-dose rates. speaking, Practically the reliability of such measurements will depend upon the experience and judgement of the individuals making the measurements, the variety of environmental situations encountered of specific radionuclides in the various land organisms at different islands were roughly correlated with the gamma dose rates. Errors in predicted levels will tend to be conservative, i.e., higher than actual levels. RECOMMENDATIONS It would be useful in any future operations to have available known mixtures of radionuclides simulating the fallout radionuclides for a particular device, or better, a sample of the raw fallout material collected at each site to be studied. This mixture could then be used to calibrate instruments, film badges and chemical dosimeters as time went on and as the spec- trum of gamma-energies changed. 10 Comparison of the decay of orRal reliability is further substantiated by the fact that the levels eh Their Pi and the time available for making such measurements.