Altogether about 80 personnel were utilized ‘in activities devoted to safety. Radiological Surveillance Radiological safety (Rad-Safe) was a separate Task Unit within the Joint Task Force organization. Rad-Safe responsibilities included procuring, storing, and issuing Rad-Safe supplies and equipment, instrument maintenance, issuance and processing of film badges, maintenance of personnel radiation exposure records, supervision of monitoring, decontamination, waste disposal activities, procurement and distribution of high density goggles, and other activities as indicated by the potential hazards of the situation. The Rad-Safe Branch contained an Off-Site Surveillance Section. Personnel from this section participated in monitoring at off-site populated islands in the vicinity of the test area and periodically collected water and food samples. 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 Aircraft Monitoring Aircraft were used to monitor the cloud of airborne radio- conducted in the lower atmosphere. Timely information on cloud movement, top and base altitudes were obtainedfor 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. Environmental Safety Off-Site Monitoring activity during early times after detonation and to track the cloud periodically over a period of two or three days. During Operation Dominic (1962) there were 35 nuclear detonations above the Pacific Ocean near Christmas and Johnston Islands. The explosive yields of these devices ranged from low kiloton into the megaton range in TNT equivalent. The height of burst for each detonation wassufficient to negate local radioactive fallout. The devices were delivered to the point of detonation by either manned aircraft or by surface-to-air missiles. In addition to the atmospheric tests, there was one underwater test of a low yield nuclear device detonated in the Eastern Pacific Ocean several hundred miles from the closest land area. Essentially all the radioactive fission products produced by this test were deposited in the ocean and were soon dispersed and diluted to concentrations which were of nosignificant biological hazard to man or marinelife. All nuclear events at Christmas Island were detonations of devices released from manned aircraft. These bursts occurred over water and were planned for execution underfavorable atmospherie conditions to minimize the likelihcod 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 composedof scientific personnel of contractor laboratories (Lawrence Radiation Laboratory, Aa 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) primary stations, (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 document all 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 Project Groups and Weather Groups. Background stations on Tu- 47