were planned for execution under favorable atmospheric conditions to minimize the likelihood of contamination of land surfaces. In addition, following each event, ground and aerial monitors surveyed the island to determine whether any radioactive rain-out occurred, A Hazards Evaluation Unit composed of scientific personnel of contractor laboratories (Lawrence Radiation Laboratory, Los Alamos Scientific Laboratory, Sandia Corporation) and representatives of the U. S. Weather Bureau was organized to advise the Commander of the Joint Task Force and the Scientific Deputy. for each detonation. Pre-shot computations were made These computations included a fallout trajectory forecast for the surface, 10,000, 20,000 and 30,000 feet winds out to 12 to 24 hours, and a predicted radiation exclusion area based upon predicted winds. Where applicable, other weapons phenomena were considered such as blast pressures ,/possible eye injuries from the prompt thermal radiation Cloud tracking aircraft made ‘and maintained contact for several hours with the radioactive cloud following each event conducted in the lower atmosphere. Timely information on cloud movement, top and base altitudes were prepared for use of advisory regarding opening of conmmercial air lanes through or near the announced danger area. no evidence There was that ary commercial aircraft encountered any of these radio- active clouds. Off-Site Monitoring The Off-Site monitoring program during Operation Dominic was under the cognizance of the U. S. Public Health Service, USPHS personnel being assigned to JIF-8 during the operational phase. The program Gl