From Abstract: "An Aerial Radiological Measuring Survey (ARMS) of the Las Vegas area was made for the Civil Effects Test Operations, Division of Biology and Medicine, U.S. Atomic Energy Commission, by Edgerton, Germeshausen & Grier, Inc., between May 21 and June 23, 1961. The survey was part of a nationwide program to measure present environmental levels of gamma radiation. Approximately 6000 traverse miles were flown, at an attitude of 500 ft above the ground, in a 100-mile square centered near Las Vegas. The EG&G ARMS-II instrumentation was used in the survey."