will remain captured and thus, of course, completely eliminate any fallout. Prior to each nuclear detonation a "warning circlet is estab lished for aircraft, designed to provide control of aerial flights within the area of predicted path of the atomic cloud. A répresentative of the Civil Aeronautics Administration is assigned tothe test organization and assists in establishing the controlled area. This may typically extend about 150 miles in radius and be in force for a period from about H minus one-half hour to H plus 10 hours. All aircraft are required to check through the Civil Aeronautics Administration before flying in this area. After each miciear burst, aircraft from the Test Organization track the cloud until it is no longer readily detectable. Behind this come other aircraft to plot the fallout pattern on the ground. This survey is repeated on D plus one day. The off-site monitoring program during Operation Plumbbob (Spring 1957) illustrates the exteasive system organized not only to take numerous radiological measurements but also to provide close liaison with the citizens of nearby communities. The Atomic nergy Commission and the U. S. Public Health Service jointly organized a program wnerein the areas around the test site are mapped out into 17 zones. A techni- cally qualified man has bean assigned to live in each zone. His duties consist not only of normal monitoving activities but also, prior to and during the test series, of learning the communities and families in his zone, getting to know the people and having them know him. In addition to the 17 zone commanders, as they are called, there are - 28 - ; | i