Operation IVY, of conducted at Eniwetok in November 1953. these measurements present in highest the showed Pacific Evalustion that only very low radioactivity was Islands. Outside Eniwetok Atoll the reading was approximately 1.5 milliroentgens per hour of gamma radiation 60 hours after the first detonation. sampling unlts set up at a number of Air islands were not activated since fall-out did not reach the minimum measurable value of OLS :milliroentgens per hour, In the United States, observations disclosed air activity 500 times above normal at Hanford, Washington, but this value declined quickly. Neither this amount nor the much lower values measurcd elsewhere in the United States constituted a health hazard. Operation UPSHOT-KNOTHOLE. 4, Fall-out data. UPSHOT-KNOTHOLE, The first & detonations of Operation the current cpring tests at the Nevada Proving Ground, have produced significantly higher fall-out than those of previous sertes. from tower shots The relatively heavy fall-outs of higher energy yield than continental tests. 5. These those & resulted in previous (See Part III, Weapons.) highest gamma doses Location in populated areas were: Population Riverside Cabins, Nevada 13 weeks Gamme dose Lifetime (roentyrens) 14 7.0 11.0 200-300 5,5 8,0 Lincoln Mine, Nevada 200 3.0 3.8 vo Rockville, Utah 300 O21 2.85 ‘ Bunkerville, Nevada 6. standard These of . values may be 3.9 roentgens for compared with the Commissicn's 13 weeks as a maximum permissible dose. - 59 - Part VI