Weather predictions were conducted by the Navy and Air Force Air Weather Service. To assist in analyzing the weather data and to predict other results such as thermal effects, a Hazards Evaluation Unit was formed to advise the Joint Task Force Commander and his Scientific Deputy. Radiological safety activities on-site were conducted by a special unit of Joint Task Force 8 and off-site surveillance programs by the U. S. Public Health Service. Altogether about personnel were utilized in activities devoted to safety. Radiological Surveillance Radiological safety (Rad-Safe) was a separate Task Unit within the Joint Task Force organizations. Rad-Safe responsibilities included procuring, storing, and issuing Rad-Safe equipment, the issuance and processing of film badges, the maintenance of personnel radiation exposure records, supervision and monitoring of decontamination and 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. Per- sonnel from this section participated in monitoring off-site populated islands in the vicinity of the test area and periodic collection of water and food samples. Aircraft Monitoring Aircraft were used to monitor the cloud of airborne radioactivity during early times after detonation and to track the cloud periodically over a period of two or three days. 54.