| ee Pou a Ciceccan j USE (i AN CEL cul Y nevosironv AL. LOS Alynos MetZAR COVY ~ t COLLECTION : BOX No. L331 May 25, _. FOLDER Gs Cancel, “Be. Gordon Bumning 7 _ Washington 25, B; . - 1954 | oe : Division of Biolegy and Medicine=. «Ct ¥. 8, Atomic Energy Comission | 404559 Pt net _ mm: 7 “BEST COPY AVAILABLE Bear Gorden: The follewing report dated May 24 has just been suimitied to me by Bill Johnson. Will you be good enough to see to it that the information is given the proper distribution? ®Since 2/19/54, nearly continuous monitoring has been in progress for the detection of contamination of possible Pacific origin. This has consisted of air sampling for concentration and sise of radioactive fallout particles and a recording G-M tube instrument for observing changes in surface activity, Samples pricr to 3/1/54 were used to develop a standard decay curve for normal background radiation and all succeeding samples were compered to this curve. Filter samples were changed twice daily throughout the period of eoncern. Two periods of significant change in normal background were observed. The first eccurred between 0600-1620 on 4/5/54 when the air concentration approached ten times normal background. The rise and fall of the air concentration took place within a 24-hour period, SucGessive counte indicated that the material decayed with a slope of 2.0 on the basis of « 3/26/54 origin. The second period of interest is not yet completed. Air concentra- tions about five times norma] vere observed en 5/10/54. A hea vain occurred during this day also, which contained 0.3 wo of beta activity per liter. Rain water from succeeding a showers was yadio~-assayed but the highest eonsentration found ms. only about 0.03 uc/liter. Surface beta activity was noted to be eto eeeey ermal backgroun! when measured with epen-shield O-M The sontamination resulting from this latest incident is still in the air and on the ground in detectable quantities. Ten representa- tive air samples have been observed for decay. Five of the decay curves exhibited a slope between -1.0 and -1.5 an the basis of 5/4/54 origin while the remaining five fell off more rapidly vith ole