"The phenomenon known as 'fallout' came into being in 1945 with the detonation of the first 'atomic bomb' in New Mexico, July 16, 1945. Fallout received world wide attention after the March 1, 1954, test BRAVO, a 15 MT thermonuclear device detonated at Bikini Atoll. Fallout is the process of the descent to the earth's surface of particles contaminated by fission products from the radioactive cloud. The term is also applied to the contaminated particulate matter itself. The radiation emitted by these particulates is called fallout radiation. Early (or local) fallout is conventionally defined as that which reaches the earth's surface within 24 hours. Delayed (or worldwide) fallout consists of finer particles from the upper troposphere and the stratosphere and are spread by winds across the globe. Its descent extends over months and years. The chapter begins with introductory materials to acquaint the reader with the phenomenon and the basic aspects of radioactivity in fallout. It then summarizes the basis for predicting early fallout from surface-burst weapons. Six panels follow on what would be observed by the eye and with radiation detection instruments in the area affected by early fallout. The next topics treated are shielding from fallout radiation and changes expected due to differing winds and weapon sizes. Another major section is devoted to contact and internal hazards of fallout radiation and its effects on animals and plants. The special problems of urgent emergency operations in damaged areas where fallout is present also are discussed. Finally, a section is devoted to some common questions about fallout. The chapter concludes with a list of references and suggested additional reading for those who are interested in further or more detailed information."
Federal Emergency Management Agency 130; FEMA 130
United Stated Federal Emergency Management Agency, Learning Resource Center: http://www.lrc.fema.gov/