A press release issued on this date by the Department of Defense:
The National Fallout Shelter Sign will be a familiar sight in communities all over the United States next year. It will mark buildings and other facilities as areas where 50 or more persons can be sheltered from radioactive fallout resulting from a nuclear attack. The sign will be used only to mark Federally-approved buildings surveyed by architect-engineer firms under conract to the Department of Defense. The color combination, yellow and black, is considered as the most easily identified attention getter by psychologists in the graphic arts industry. The sign can be seen and recognized at distances up to 200 feet. The shelter symbol on the sign is a black circle set against a yellow rectangular background. Inside the circle, three yellow triangles are arranged in geometric pattern with the apex of the triangles pointing down. Below the fallout symbol, lettered in yellow against black, are the words FALLOUT SHELTER in plain block letters. Yellow directional arrows are located directly underneath the lettering which will indicate the location of the shelter.
"An Indelible Cold War Symbol: The Complete History of the Fallout Shelter Sign" (from conelrad.blogspot.com): @
* Signs page from Civil Defense Museum: @
* Signs page from Health Physics Instrumentation Museum Collection (Oak Ridge Associated Universities, Tennessee): @
* "Protection Factor 100" (1963 Office of Civil Defense film about National Fallout Shelter Survey Program): @
* "September 1961: Fallout shelters" (blog entry): @