V. CONCLUSIONS The energy spectra and angular exposure rate distributions for fallout sources differ considerably from those for the natural emitters because of the different source depth distributions. The magnitude of this difference depends on the exact depth distribution of the fallout emitters. The computations in this report indicate that both distributions also vary with detector height, emphasizing the necessity of carefully calibrating detectors used for measuring gamma radiation in the field. The calculated exposure rates, differential energy Spectra, and angular exposure rates can be used for inter- preting and analyzing the results of land and aerial surveys over extensively contaminated areas as well as for predicting ‘the results of such surveys for a known level of contamination. In certain instances experimental data taken at high altitudes can be used to infer information about the radiation field near the interface. This can be done by utilizing the curves given in this report, taking into account the source spectrum and depth distribution of the isotopes contributing to the field.