a on material. Obviously, this is not correct but how far this deviates from the facts and to what extent this influences the results is diffi- cult to assess. Calculations indicate that the production of recogniz- able beta burns from a single particle requires a high specific activity. particles of fallout are close enough to have overlapping of radiation fields and thus require significantly lower specific activity of the particles to produce beta burns. This hypothesis has support in that even the most superficial beta burns of the natives exposed to fallout following the March 1, 1954 detonation showed a general area affected rather than small individual spots. On the other hand, the cattle and horses exposed near the Nevada Test Site showed burns over areas only about the size of a quarter. aE meen, It may well be, however, that the Spee nlpeenne meanest gr oe (See Criteria III for discussion.) Even though these may not have been pro- duced by single particles, they do represent less of an area effect than suggested for the natives. Also, radiocautographs of the fallout in areas outside the Nevada Test Site suggest the occurrence of indivi- PARTICULATE NATURE OF FALLOUT IT WOULD NOT BE POSSIBLE TO ESTABLISH REASONABLE AND OPERATIONALLY WORKABLE CRITERIA THAT AT THE SAME TIME WOULD GUARANTEE THAT THERE NEVER WOULD BE AN OCCURRENCE OF A BETA BURN. If one were to accept the assumed beta to gamma dose rates of about 100-200 to 1 (measured under the conditions given above), this might mean an infinity beta dose of 1000-2000 reps to the basal layer of the “tie a epidermis when the whole body infinity gamma dose was 10 roentgens. . WITH OUR PRESENT KNOWLEDGE IT SHOULD BE STATED THAT DUE TO THE pra definite overlapping of the fields. Ey rE ope nearby areas where the fallout was relatively heavy, there was a Paneer However, in mp dual particles with non-overlapping of radiation fields.