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. Pre-shot computations were made for each detonation. These computations included 12 and 24 hour trajectory forecasts based on winds from the surface to 40,000 feet. A specified radiation exclusion area was then declared to include any possible local fallout. Daily soundings were made to 100,000 feet giving added information that was helpful in correlating observed cloud stabilization and movement with predicted shot-time trajectories. Where applicable, other weapons phenomena were considered such as blast pressures, and 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 obtained for use of advisory reports regarding opening of commercial air lanes through or near the announced danger area. There was no evidence that any commercial aircraft encountered any of these radioactive 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 JTF-8 during the operational phase. A radiological surveillance of a network of 19 monitoring stations was maintained on populated islands within a 2,000 mile radius of Christmas Island. Air samples were collected on populated islands out to about 1,000 miles from the test zone. Samples of soil, vegetation, fruits, water and marine life were collected on the populated islands of the area before testing began and repeated sampling was made after the testing period to determine whether changes in the level of radioactivity had occurred in the area. The 19 sampling stations were divided into (1) primarysta- tions, (2) secondary stations, and (3) background stations. The primary stations (Christmas, Fanning and Washington) were manned by USPHS officers with equipment and sampling tech- niques to documentall forms of environmental radioactivity. The secondary stations (Canton, Malden, Penrhyn/Tongareva, Palmyra, Midway, Johnston Island and French Frigate Shoals) were outside the danger area and were designed to document air concentration and external radiation background. These stations were operated with the assistance of Task Force Pro}ect Groups and Weather Groups. Background stations on Tu- S00 100 | 47