Downwind

Estimated Fallout Pattern from Nuclear Air Burst

Delayed ionizing radiation dose (fallout)

• Produced by fission products and neutron-induced radionuclides in the area around the explosion, especially downwind
• Dispersed downwind with the fireball/debris cloud.
• As the cloud travels downwind, the cooling and falling radioactive material settles on the ground creating a large swath of deposited material (fallout).
• Fallout creates large areas of contamination and the ionizing radiation coming off the fallout which can damage tissues and penetrate through thin walls and glass.
• Fallout can also contaminate the soil, food and water supply

Map of New Mexico showing the Trinity Test Site, nearby cities, and radiation levels along the fallout pattern.

Courtesy of Atomic Archive (LA 1027-DEL).

Fears of nuclear war led federal and state governments to make emergence plans. The development of interstate highways was due to a perceived need to evacuate cities. Communities looked for places that could offer shelter to the public and individuals were encouraged to designate safe spaces in their homes with supplies that could last for weeks. 

Even after the bombing of Hiroshima and Nagasaki there was still a great deal that was unknown about the long-term effects of nuclear bombs. Although there was awareness that radioactivity was dangerous, most of the information available was from studying the effects of the bomb on the Japanese victims. The early studies focused on the immediate effects such as burns and severe radiation burns. 

Over time, the recommendations to the public would change. A famous filmstrip from 1952 recommends children hide under their desks or under a picnic blanket. This information was based on the studies mentioned previously.

The effects of atomic bombs on Hiroshima and Nagasaki / United States Strategic Bombing Survey, Chairman's Office, 1946

Fallout from nuclear tests at the Nevada Test Site / by Gordon M. Dunning ... Prepared for presentation at the hearings on fallout before the Joint Committee on Atomic Energy, May 5-8, 1959

New Mexico SP Abo Elementary School and Fallout Shelter (National Register of Historic Places).

"Located in the small southeastern New Mexico town of Artesia , the Abo Elementary School was built in 1962 to function as both a school and an underground fallout shelter for the community during the height of the Cold-War after plans by Roswell New Mexico architect, Frank M. Standhardt. With the exception of three, flat-roofed concrete block buildings (linked by a canopy to form a roughly shaped Lin plan), the building is located completely underground and was engineered to withstand the effects of a thermonuclear blast. This was achieved by excavating below grade and constructing steel reinforced cast concrete walls and posts to support a 21-inch thick concrete slab roof. Heavy steel doors, designed to hold up under a nuclear explosion , were placed inside the three above ground entrances."

Abo Elementary School and Fallout Shelter (National Park Service)

As multiple countries developed nuclear weapons emergency plans evolved and included evacuating and sheltering in place. By 1958 there were plans available to the public for building a variety of fallout shelters. In the 1960's public shelters were designated in communities across the country. These were often public buildings such as libraries, court houses, and schools.  Many of these plans were for adding or altering existing spaces for use as a shelter but some plans were available for new construction and awards were given for new architectural designs.

The family fallout shelter, United States. Office of Civil and Defense Mobilization. 1959

National school fallout shelter design competition, Office of Civil Defense, 1963