re i i eet m poey widely vithin sill geographical areas and even at the same location at dif ferent times (taking into account radioactive cecay). cannot be placed in precise values, Thus, confidence Table VI.a. suggests that even if one were to have stored up the water listed at Virgin River Irrigation Canal the concentration vould be about 58 tires less then the meximu. rermissible amount. Normal factors of dilution by additional rainfall and/or by the influx of lesser contaninated ground water would be expected to reduce the level of activity. fix Considerable effort has and iis being node to evaluate hazeris fron eirborne radionctive materials, including fissien products. a en eee ale See: : end subsisted entirely on this for a Lifetime, There ere certuimy many unanswered problems including the possible hazard from a single particle in the lings. Despite the uncertainties and as yet in- complete analysis of the inhalation hazard, the preponderance of evidence today is that the external gamma hazard from fsilout is the more aimiting factor of the two", (However, see ciscussion on food contamination. ) During Upshot-#nothole quite complete data were collected of concentrations of airborne activity on about 150 occasions in some 40 different localities within 20U miles of the Nevada Proving Grounds. included monitoring of all detonations. These Histosroms were made of air con- centrations versus time after detonation for 30 occasions and estimates were These data for the five commmnities showing the highest air concentration are given in Table VI.b. The histogram for St. George (the highest 24 hour average concentration of fallout ever in opulated area eproduced in appendix J *Ad Hoc Committee Meeting. Washington, D. C, January 20, 1954. ee made of doses to the lungs.