debris could place a considerable amount in the trade wind flow to be brought back into the general area of the tests. The greatest effect from this mechanism occurred following the!SHor/, The deposition of radioactive material on native atolls to the east of Bikini following| S407" / of these atolls. was such as to necessitate evacuation (See Chapter IV). Although subsequent shots did not add appreciably to this initial deposit, continucus additions of small amounts of contamination can eventually create an apprecia~ ble background of leng-lived fission preducts. 2. Interference with Air Routes and Protection of Tran~ sient Shipping. In the detonation of devices as large as those tested during Operation CASTLE, a problem arises in connecticn with the protection of air and sea routes througn this area. Again, the problem is a principal concern of the radiological safety planners. In reference to air routes, definitive data on this subject were passed to CINCPACFLY with specific recommendations for slosing 4 specified route for a specified length of time. In order to provide prcetection for transient shipping in the region, a high degree of coordination was necessary. CINCPACFLT was requested to make advance diversions of shipping outside a sector area from southwest clockwise through norvh to east, to 500 nautical miles from ground zeros from H to H pins 24 hours. A fur- ther modification subsequent to [SHor/, provided that all U. S. shipping passing within 600 nautical miles of Bikini would come