sbout 52 tine: lese than the maxinun permiszible azsount. Norma) facters of dilution by additional reinfell and/or by the influx of lesser contaminated k frgt Tet ground water vould. reduce the level of activity. dix Considerable effort has and is being made to evaluste hazards fron sirborne radioactive materials, including fission products. There are eer- tainly many unansvered problezs including the possible basard frem a aingle particle in the lungs. Despite the uncertainties and as yet incesplete analysis of the inhalation hazard, the mreponderance of evidence today is that the external gamma hazarc fron fallout is the more the twot. liniting factor of (However, see discussion on food contanination.) During Upshot-Knothole quite complete data were eollected of concentrations of airborne activity en about 150 occasions in some 40 different localities within 200 miles of the Fevada froving Grounds, monitoring of all detonations. These included Histograms were nade of air eoncentrati ons vercus tine efter detonation for 30 eecasions and estimates were sade of deses to the lungs. DOE/NV These data for the five communities showing the highest alr coucentrution are given in Table Vi.b. The histogram for St. George (the et high[ats hour average concentration of fallout ever measured in a populated aren) 43 reproduced in Appendix J. #Acd Hoc Comittes Meeting. Washington, D.C, January 20, 1954. Ue ACC rien Meek oe 4A