DISCUSSION OF RESULTS I. Sr90 Surface Air Concentration Data Large air blower samples, collected over the last several years at the Naval _ Research Laboratory, Washington, D, C. by I. H. Blifford and associates, were made available to us for Sr” assay. Collections were made on Army Chemical Corps Type V filters of 200 square inches area and of heavy asbestos fiber composition, Collection volumes ranged from about 1 to 5 million cubic feet of air for collection periods of one day to one week. The large blower samples which were analyzed from Sr?” were collected from four locations: Washington, D. C.3 Kodiak, Alaska; Port lyautey, French Morocco; and Yokosuka, Japan. A summary of the Sr90 concentration data, together with the location, collection period and sample volume for each sample, is presented in the last section of this report. . The Washington, D. C. Sr90 air concentration data are presented in Figure 1. For these samples, the volumes were computed from recorded flow rate data. Figure 2 shows the ‘variation in total flow with length of the collection due to dust loading of filtersat the lashington, D. C, station, This curve was obtained from Mr, Blifford at the Naval Research Laboratory, who indicated quite large variations of individual collection volumes from the average values shovme The data for the three foreign stations are presented in Figure 3, For these, the collection volumes were not monitored and the volume of each sample was estimted by assuming the effect of dust loading observed at Washington, D.C. (Figure 2) applied equally well at these other locations, The necessity of making this assumption imposes a restriction on comparison of relative air concentrations for the four locations but does allow us to consider the change in air concentration with time at each location.