ad ( ye atte Size (um) cont. 239py (dpm/¢) .01 to 1.1 4go Total 730 Soil 2700 The average mass loading during this experiment was 70 ue/m, there is some spread in the date, While there is no indication cf a preferential association of 23%p, with a particular particle size, and as would be expected due to dilution by inert aerosol, the activity is lower than that in the soil. If we assume that this is generally true, a method of predicting resuspended air activity of 239py would be to simply multiply the ambient mass loading by the soil activity. For small islands like the Eniwetok group, the ambient mass loading would be expected to be very low. be of the order of 10 we/m? 10. Minimum values of mass loading are believed to The National Air Pollution Central Administration has reported measurements of mass loading at nonurban U.S. locations for the 1966 calendar year’, Arithmetic mean values range from 9 to 79 we /m>; the average of all locations was 38 we/m>. The arithmetic mean of the measurements at urban Honolulu, Hawaii, was 35 ue/m>. Some potential problems in using this approach should be mentioned. Although the data from NTS support the premise that the activity per gram of material collected by air sampling is lower than that in the soil in the area, this could perhaps be fortuitous due to dilution with inert aerosol. There is no way of determining the origin of the material collected by the sampler, and it would seem unlikely that a major fraction of the collected mass actually originated from the soil surface within even a few hundred meters of the sampler. ro da ee wt sop gee sep yee + _ os1 PRA ONSem SOLIDa>TR TE me eas ak 2d * ae, - - or wi ek, Plea aa he ne ’ wt ‘a aren A et -” SRT VIet ARE 7a ree, oO ‘ 1h veh a , weve, ge ih TE mgt ea ty nee ~ rae . if ~-