ee agerepyymeatiag eed, of 107? to 107!" The U. K. made observations on resuspension following the HURRICANE firing (Monte Bello Islands). An average value of 107? was obtained for the resuspension factor at early times after deposition and under conditions when the ground nearby was disturbed mainly by wind and natural turbulence. The results of trials in the Australian desert indicate the effect of very arid conditions, where a mean value of 10 7 was measured. A decrease in the resuspension value was observed between 4 and 7 days following the test, suggesting a dilution by mixing of the deposited activity within the top layers of soil. It was estimated that mixing in the top layer of dry Australian desert provided a dilution factor of at least 10° per millimeter depth. Limited studies have been made on the possible enhancement of resuspension by mechanical means. The results suggest that vehicular traffic may increase normal resuspension by not more than an order of magnitude, if at all. Penetration of plutonium oxide in Nevada soil is largely confined to the top 1 1/2 inches. However, in Bikini soil, penetration of plutonium was observed to a depth of 9 inches (the deepest sample analyzed). This latter is undoubtedly due to the type of soil, the constant high humidity in the area, and the many years of soil weathering.