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{{Short description|Space protecting occupants from radioactive debris}}
{{About||the 2015 video game|Fallout Shelter|the Island Records studio known as The Fallout Shelter|22 St Peter's Square|the Yugoslav hard rock band known internationally as Atomic Shelter|Atomsko Sklonište}}
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[[File:Fallout shelter sign (US).jpg|thumb|A fallout shelter sign in the United States of America, designed in 1961 by  [[United States Army Corps of Engineers]] director of administrative logistics support function [[Robert Blakeley|Robert W. Blakeley]]]]

A '''fallout shelter''' is an enclosed space specially designated to protect occupants from radioactive debris or [[nuclear fallout|fallout]] resulting from a [[nuclear explosion]]. Many such shelters were constructed as [[civil defense]] measures during the [[Cold War]].

During a nuclear explosion, matter vaporized in the resulting fireball is exposed to neutrons from the explosion, absorbs them, and becomes [[radioactivity|radioactive]]. When this material condenses in the rain, it forms dust and light sandy materials that resemble ground [[pumice]]. The fallout emits [[Alpha particle|alpha]] and [[beta particle]]s, as well as [[gamma ray]]s.

Much of this highly radioactive material falls to Earth, subjecting anything within the line of sight to radiation, becoming a significant [[radioactive contamination|hazard]]. A fallout shelter is designed to allow its occupants to minimize exposure to harmful fallout until radioactivity has [[Radioactive decay|decayed]] to a safer level, over a few weeks or months.

{{Clear}}
== Principle ==
[[File:Fallout shelter photo.png|thumb|Idealized American fallout shelter, around 1957.]]
A fallout shelter is designed to protect its occupants from:

* the mechanical and thermal effects of a nuclear explosion (or nuclear accident);<ref>{{Cite web |date=2017-01-27 |title=Un abri antiatomique au fond de votre jardin |url=https://www.capital.fr/votre-argent/un-abri-antiatomique-au-fond-de-votre-jardin-1202870 |access-date=2023-12-31 |website=Capital.fr |language=fr}}</ref>
* radioactive fallout, allowing them to survive for a period of time deemed sufficient to allow them to escape safely.

== History ==

=== North America ===
[[File:Fallout shelter water storage can.jpg|thumb|Fallout shelter water storage can: a {{convert|17+1/2|usgal|L|order=flip|sp=us}} barrel issued by the  U.S. Department of Defense, Office of Civil Defense. 1963]] During the [[Cold War]], many countries built fallout shelters for high-ranking government officials and crucial military facilities, such as [[Project Greek Island]] and the [[Cheyenne Mountain nuclear bunker]] in the United States and Canada's [[Emergency Government Headquarters]]. Plans were made, however, to use existing buildings with sturdy below-ground-level basements as makeshift fallout shelters. These buildings were [[placard]]ed with the orange-yellow and black [[trefoil]] sign designed by [[United States Army Corps of Engineers]] director of administrative logistics support function [[Robert Blakeley|Robert W. Blakeley]] in 1961.<ref name="rdmcfddnnyt">{{cite web |last1=McFadden |first1=Robert |title=Robert Blakeley, Who Created a Sign of the Cold War, Dies at 95 |url=https://www.nytimes.com/2017/10/27/obituaries/robert-blakeley-whose-fallout-shelter-sign-symbolized-the-cold-war-dies-at-95.html?_r=0 |website=[[The New York Times]] |access-date=8 August 2019 |archive-url=https://web.archive.org/web/20180805160704/https://www.nytimes.com/2017/10/27/obituaries/robert-blakeley-whose-fallout-shelter-sign-symbolized-the-cold-war-dies-at-95.html?_r=0 |archive-date=5 August 2018 |language=en |date=27 October 2017}}</ref>

The [[National Emergency Alarm Repeater]] (NEAR) program was developed in the United States in 1956 during the Cold War to supplement the existing siren [[warning systems]] and radio broadcasts in the event of a [[nuclear attack]]. The NEAR civilian alarm device was engineered and tested but the program was not viable and was terminated in 1967.<ref name=nearProgram>{{cite web|title=Episode 709, Story 3: N.E.A.R Device|url=http://www-tc.pbs.org/opb/historydetectives/static/media/transcripts/2011-05-22/709_near.pdf |archive-url=https://web.archive.org/web/20130921060606/http://www-tc.pbs.org/opb/historydetectives/static/media/transcripts/2011-05-22/709_near.pdf |archive-date=2013-09-21 |url-status=dead|website=pbs.com|publisher=Oregon Public Broadcasting|access-date=October 9, 2014|page=11|format=transcript|year=2009}}</ref>

In the U.S. in September 1961, under the direction of [[Assistant Secretary of Defense for Homeland Defense and Americas' Security Affairs#Precedent|Steuart L. Pittman]], the federal government started the Community Fallout Shelter Program.<ref>{{cite web|url=http://www.civildefensemuseum.com/cdmuseum2/commun.html|title=Civil Defense Museum-Community Shelter Tours Main Page|publisher=civildefensemuseum.com|access-date=September 14, 2008}}</ref><ref>{{cite web|url=http://mywebtimes.com/archives/ottawa/display.php?id=366305|title=FALLOUT FEVER: Civil Defense shelters dotted area cities during the Cold War&nbsp;– My Web Times|publisher=mywebtimes.com|access-date=September 14, 2008|archive-url=https://web.archive.org/web/20120305044705/http://mywebtimes.com/archives/ottawa/display.php?id=366305|archive-date=March 5, 2012|url-status=dead}}</ref> A letter from [[John F. Kennedy|President Kennedy]] advising the use of fallout shelters appeared in the September 1961 issue of ''[[Life (magazine)|Life]]'' magazine.<ref>{{cite web |url=http://www.em.doe.gov/Publications/timeline_sep1961.aspx |title=DOE.gov |archive-url=https://web.archive.org/web/20091107064343/http://www.em.doe.gov/Publications/timeline_sep1961.aspx |archive-date=7 November 2009 |url-status=dead}}</ref> From 1961 to 1963, home fallout shelter sales grew, but eventually{{when|date=March 2023}} there was a public backlash against the fallout shelter as a consumer product.<ref>{{Cite journal|last=Bishop|first=Thomas|date=2019|title="The Struggle to Sell Survival": Family Fallout Shelters and the Limits of Consumer Citizenship|journal=Modern American History|language=en|volume=2|issue=02|pages=117–138|doi=10.1017/mah.2019.8|issn=2515-0456|doi-access=free}}</ref>

In November 1961, in ''[[Fortune (magazine)|Fortune]]'' magazine, an article by Gilbert Burck appeared that outlined the plans of [[Nelson Rockefeller]], [[Edward Teller]], [[Herman Kahn]], and [[Chet Holifield]] for an enormous network of concrete-lined underground fallout shelters throughout the United States sufficient to shelter millions of people to serve as a refuge in case of [[nuclear war]].<ref>[[Fortune (magazine)|''Fortune'']] magazine November 1961 Pages 112–115 et al</ref>

The United States ended federal funding for the shelters in the 1970s.<ref>{{cite news|last1=Bearman|first1=Sophie|title=Thinking the unthinkable: Don't rely on these historic fallout shelters in case of a nuclear attack|url=https://www.cnbc.com/2017/10/06/thinking-the-unthinkable-dont-rely-on-these-historic-fallout-shelters-in-case-of-a-nuclear-attack.html|access-date=27 December 2017|publisher=CNBC|date=6 Oct 2017}}</ref> In 2017, New York City began removing the yellow signs since members of the public are unlikely to find edible food and usable medicine inside those rooms.<ref>{{cite news|last1=Allen|first1=Jonathan|title=New York City To Remove Misleading Nuclear Fallout Shelter Signs|url=https://www.huffingtonpost.com/entry/new-york-city-nuclear-fallout-shleter-signs_us_5a43816ce4b025f99e18e04d?ncid=inblnkushpmg00000009|access-date=27 December 2017|agency=Reuters|work=Huffington Post|date=27 December 2017}}</ref>

====Atomitat====
The [[Atomitat]] was an underground house in [[Plainview, Texas]]: it was designed by [[Jay Swayze]] and completed in 1962. The house was designed in response to the fear of nuclear war during the Cold War. The house was designed to be an "atomic-habitat" which met the [[United States Civil Defense]] specifications.<ref name="KCBD">{{cite news |title=Whatever Happened to the Atomitat? |url=https://www.kcbd.com/story/884442/whatever-happened-to-the-atomitat/ |access-date=26 April 2022 |agency=KCBD |publisher=A Gray Media Group, Inc |date=6 August 2002}}</ref> It was the first bunker-house to meet their specifications as a nuclear shelter.<ref name="McDonough">{{cite news |last1=McDonough |first1=Doug |title=Atomitat House used in 1966 propaganda film |url=https://www.myplainview.com/news/article/Atomitat-House-used-in-1966-propaganda-film-8414795.php#photo-10645855 |access-date=26 April 2022 |publisher=Plainview Herald |date=27 April 2012 |archive-date=March 10, 2022 |archive-url=https://web.archive.org/web/20220310202028/https://www.myplainview.com/news/article/Atomitat-House-used-in-1966-propaganda-film-8414795.php#photo-10645855 |url-status=dead }}</ref> Swayze also built an underground house for the [[1964 New York World's Fair]]: it was called the [[Underground World Home]].<ref name="Bounds">{{cite book |last1=Bounds |first1=Anna Maria |title=Bracing for the apocalypse : an ethnographic study of New York's 'prepper' subculture |date=2021 |publisher=Routledge |location=Abingdon, Oxon |isbn=978-0415788489 |edition=1st |url=https://books.google.com/books?id=ennpDwAAQBAJ&dq=Underground+World+Home+world%27s+fair&pg=PT52 |access-date=24 April 2022}}</ref>

=== Europe ===
Similar projects have been undertaken in [[Finland]], which requires all buildings with area over 600&nbsp;m<sup>2</sup> to have an NBC (nuclear-biological-chemical) shelter, and [[Norway]], which requires all buildings with an area over 1000&nbsp;m<sup>2</sup> to have a shelter.<ref>{{cite web|url=http://www.lovdata.no/for/sf/jd/xd-19950315-0254.html |title=FOR 1995-03-15 nr 254: Forskrift om tilfluktsrom |publisher=Lovdata.no |access-date=August 15, 2012}}</ref>

The former [[Soviet Union]] and other Eastern Bloc countries often designed their underground mass-transit and subway tunnels to serve as bomb and fallout shelters in the event of an attack. Currently, the deepest subway line in the world is situated in [[St Petersburg]] in [[Russia]], with an average depth of 60 meters, while the second deepest subway station is [[Arsenalna (Kyiv Metro)|Arsenalna]] in [[Kyiv]], at 105.5 meters.<ref>{{cite web |last1=Pile |first1=Tim |title=Going underground: the cheapest, deepest, oldest subway systems in the world – but which is home to its own mosquito? |url=https://www.scmp.com/magazines/post-magazine/travel/article/3119562/going-underground-cheapest-deepest-oldest-subway |website=South China Morning Post |date=January 29, 2021 |publisher=SCMP Publishers |access-date=28 February 2022 |archive-url=https://web.archive.org/web/20210906060723/https://www.scmp.com/magazines/post-magazine/travel/article/3119562/going-underground-cheapest-deepest-oldest-subway |archive-date=6 September 2021}}</ref>

Germany has protected shelters for 3% of its population, [[Austria]] for 30%, [[Finland]] for 70%, [[Sweden]] for 81%,<ref>{{cite news|url=https://www.thelocal.se/20171101/why-sweden-is-home-to-65000-fallout-shelters/|title=Why Sweden is home to 65,000 fallout shelters |newspaper=The Local Sweden |date=November 2017 |publisher=thelocal.se |access-date=June 1, 2021}}</ref> and Switzerland for 114%.<ref name=SWI/>

==== Bosnia ====
[[File:BunkerTito-Acceso.jpg|left|thumb|266x266px|Bosnia's Ark underground facility.]]
The [[Armijska Ratna Komanda D-0]], also known as the Ark,<ref name="visitmycountry1">{{cite web |url=http://www.visitmycountry.net/bosnia_herzegovina/bh/index.php/160-turisticke-atrakcije/nase-preporuke/360-titov-bunker-ark-d0-konjic |title=Titov bunker ARK D0 - Konjic |publisher=Visitmycountry.net |date= |accessdate=2015-10-21 |archive-date=May 30, 2016 |archive-url=https://web.archive.org/web/20160530220407/http://www.visitmycountry.net/bosnia_herzegovina/bh/index.php/160-turisticke-atrakcije/nase-preporuke/360-titov-bunker-ark-d0-konjic |url-status=dead }}</ref> was a Cold War-era nuclear bunker and military command centre located near the town of [[Konjic]]<ref name="sandzacke1">{{cite web|author= |url=http://www.sandzacke.rs/magazin/zanimljivosti-zabava/ark-najvece-atomsko-skloniste-bivse-jugoslavije/ |title=ARK – najveće atomsko sklonište bivše Jugoslavije (VIDEO) – Sandžačke novine |publisher=Sandzacke.rs |date= |accessdate=2015-10-21 }}{{dead link|date=October 2016 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> in [[Bosnia and Herzegovina]].<ref name="biennialfoundation1">{{cite web|url=http://www.biennialfoundation.org/biennials/d-0-ark-biennial-bosnia-and-herzegovina/|title=D-0 ARK Biennial (Bosnia and Herzegovina) |publisher=Biennial Foundation |date= |accessdate=2015-10-21}}</ref> Built to protect [[Socialist Federal Republic of Yugoslavia|Yugoslav]] President [[Josip Broz Tito]] and up to 350 members of his inner circle<ref name="visitmycountry1" /> in the event of an [[World War III|atomic exchange]], the structure is made up of residential areas, conference rooms, offices, strategic planning rooms, and other areas.<ref name="biennialfoundation1" /> The bunker remained a state secret until after the [[Yugoslavia Wars|breakup of Yugoslavia]] in the 1990s.<ref name="wondersofnaturewith.blogspot.co.uk">{{Cite web|url=http://wondersofnaturewith.blogspot.com/2011/01/objekat-d0-konjic.html|title=WONDERS OF NATURE WITH: DO KONJIC BOSNIA AND HERZEGOVINA|date=January 1, 2011}}</ref>

The facility is now under the authority of the [[Ministry of Defence of Bosnia and Herzegovina|Bosnian Ministry of Defense]] and is managed by the country's [[Armed Forces of Bosnia and Herzegovina|military]], guarded by a five-soldier detachment,<ref name="visitmycountry1" /> but is designated by [[Commission to Preserve National Monuments of Bosnia and Herzegovina|KONS]] as [[National monument of Bosnia and Herzegovina|National Monuments of Bosnia and Herzegovina]] and used as exhibition space for project such as Cultural Event of Europe with strong UNESCO support, and tourist attraction.<ref name="biennialfoundation1" />
[[File:Željava, Underground 5.jpg|thumb|200x200px|Željava underground military airport]]
Another underground facility is [[Željava Air Base]]''',''' situated on the border between Bosnia and Herzegovina and [[Croatia]] under the {{Lang|sh|[[Gola Plješevica]]|italic=no}} mountain, near the city of [[Bihać]]. It was the largest [[Underground hangar|underground]] [[airport]] and [[military air base]] in the [[SFR Yugoslavia|Socialist Federal Republic of Yugoslavia]] (SFRY), and one of the largest in Europe. The role of the facility was to establish, integrate and coordinate a nationwide [[early warning radar]] network in SFRY akin to [[NORAD]] in the US. The complex contained tunnels in total length of 3.5&nbsp;km (2.2&nbsp;mi), and the bunker with four entrances protected by 100-ton pressurized doors, three of which were customized for use by [[fixed-wing aircraft]]. capable in housing two full fighter [[Squadron (aviation)|squadrons]], one reconnaissance squadron, and associated maintenance facilities. It was designed and built to sustain a direct hit from a 20-[[kiloton]] [[nuclear bomb]], equivalent to that dropped on [[Atomic bombings of Hiroshima and Nagasaki|Nagasaki]]. The underground facility was lined with semicircular concrete shields, arranged every 10&nbsp;km (6.2&nbsp;mi), to cushion the impact of incoming strike. The complex included an underground water source, power generators, crew quarters, and other strategic military facilities. It also housed a [[Cafeteria|mess hall]] that could feed 1,000 people simultaneously, along with stores of food, fuel and arms sufficient to last 30 days. Fuel was supplied by a 20&nbsp;km (12&nbsp;mi) underground pipe network connected to a military warehouse on Pokoj Hill near [[Bihać]]. Nowadays, they are popular for [[urban exploration]].<ref>{{cite web |title=Zeljava Airbase |url=http://www.atlasobscura.com/places/zeljava-airbase |accessdate=27 April 2017 |publisher=[[Atlas Obscura]]}}</ref><ref>{{cite web |date=June 17, 1968 |title=Underground Aircraft Dispersal Bihac Airfield, Yugoslavia 44-50N 015-47E |url=https://nsarchive2.gwu.edu/NSAEBB/NSAEBB439/docs/Underground-Doc4.pdf |access-date=28 July 2022 |work=[[National Geospatial-Intelligence Agency|National Photographic Interpretation Center]] |via=nsarchive2.gwu.edu}}</ref><ref name="lybi">{{cite web |title=Zeljava-jna_jedinice |url=http://www.zeljava-lybi.com/opis_eng.html |accessdate=27 April 2017 |publisher=}}</ref>

==== Switzerland ====
[[File:Sonnenbergtunnel.jpg|thumb|The [[Sonnenberg Tunnel]], in [[Switzerland]], was the world's largest civilian [[Nuclear warfare|nuclear]] fallout shelter, designed to protect 20,000 [[civilian]]s in the eventuality of war or disaster ([[civil defense]] function abandoned in 2006).<ref name=SWI/><ref name=Frammery/>]]

[[Switzerland]] built an extensive network of fallout shelters, not only through extra hardening of government buildings such as schools, but also through a building regulation requiring nuclear shelters in residential buildings since the 1960s (the first legal basis in this sense dates from 4 October 1963).<ref name=Frammery>{{in lang|fr}} Catherine Frammery, [https://www.letemps.ch/suisse/2016/08/15/entrailles-sonnenberg-monstrueux-temoin-guerre-froide "Dans les entrailles du Sonnenberg, monstrueux témoin de la Guerre froide"] {{Webarchive|url=https://web.archive.org/web/20171006110917/https://www.letemps.ch/suisse/2016/08/15/entrailles-sonnenberg-monstrueux-temoin-guerre-froide |date=October 6, 2017 }}, ''[[Le temps]]'', Monday 15 August 2016 (page visited on 15 August 2015).</ref> Later, the law ensured that all residential buildings built after 1978 contained a nuclear shelter able to withstand a blast from a 12-megaton explosion at a distance of 700 metres.<ref name=wsj4>{{cite news|last=Ball|first=Deborah|title=Swiss Renew Push for Bomb Shelters|url=https://www.wsj.com/articles/SB10001424052702304231204576405700994655570|access-date=December 18, 2012|newspaper=The Wall Street Journal|date=June 25, 2011}}</ref> The ''Federal Law on the Protection of the Population and Civil Protection'' still requires that every inhabitant should have a place in a shelter close to where they live.<ref name=SWI>{{in lang|fr}} Daniele Mariani, [http://www.swissinfo.ch/fre/a-chacun-son-bunker/7485678 "À chacun son bunker"], [[Swissinfo]], 23 October 2009 (page visited on 5 August 2015).</ref>

The Swiss authorities maintained large communal shelters (such as the Sonnenberg Tunnel until 2006) stocked with over four months of food and fuel.<ref name=wsj4/> The reference ''[[Nuclear War Survival Skills]]'' declared that, as of 1986, "Switzerland has the best civil defense system, one that already includes blast shelters for over 85% of all its citizens."<ref name=NWSS1>{{cite book|last=Kearny|first=Cresson H|title=Nuclear War Survival Skills|year=1986|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|isbn=0-942487-01-X|pages=6–10|url=http://www.oism.org/nwss/s73p911.htm}}</ref> As of 2006, there were about 300,000 shelters built in private residences, institutions and hospitals, as well as 5,100 public shelters for a total of 8.6 million places, a level of coverage equal to 114% of the population.<ref name=SWI/>

In Switzerland, most residential shelters are no longer stocked with the food and water required for prolonged habitation and a large number have been converted by the owners to other uses (e.g., [[wine cellar]]s, ski rooms, [[gyms]]),<ref name=wsj4/> but a legal obligation to ensure that the shelters are properly maintained remains in effect.<ref name=SWI/>

====United Kingdom====
{{Main|Royal Observer Corps monitoring post|ROTOR|Regional seat of government}}
In the United Kingdom, a network of fallout shelters were built across the country for use by the [[Royal Observer Corps]] in its nuclear reporting role.<ref>{{cite web |last1=Ravilious |first1=Kate |title=Descend Into Great Britain's Network of Secret Nuclear Bunkers |url=https://www.atlasobscura.com/articles/england-secret-nuclear-bunkers |website=Atlas Obscura |access-date=17 January 2024 |date=11 September 2018}}</ref> Other shelters were built for the purposes of the [[ROTOR]] radar system<ref>{{cite encyclopedia |editor-first=Sandy |editor-last=Hunter |first=Alec |last=Morris |title=UK Control & Reporting System from the End of WWII to ROTOR and Beyond |encyclopedia=Defending Northern Skies |publisher=Royal Air Force Historical Society|date=1996|page=104}}</ref> and the [[regional seat of government]] scheme.<ref>{{cite book |last1=Grant |first1=Matthew |title=After the Bomb: Civil Defence and Nuclear War in Britain, 1945–68 |date=2010 |publisher=Palgrave Macmillan |location=London |isbn=978-0-230-20542-0}}</ref> The [[Military citadels under London#Pindar|Pindar]] complex in London is intended to provide its inhabitants with fallout protection in the event of nuclear attack,<ref name=":0">{{Cite web |title=T 640/384 |url=http://09b37156ee7ea2a93a5e-6db7349bced3b64202e14ff100a12173.r35.cf1.rackcdn.com/HMTPO/PO-CH-NL%200084%20PART%20A.pdf |url-status=live |archive-url=https://web.archive.org/web/20240407112630/http://09b37156ee7ea2a93a5e-6db7349bced3b64202e14ff100a12173.r35.cf1.rackcdn.com/HMTPO/PO-CH-NL%200084%20PART%20A.pdf |archive-date=7 April 2024 |access-date=7 April 2024}}</ref> as was the earlier [[Central Government War Headquarters]] in Corsham.<ref name="Colson">{{cite news|last=Colson|first=Thomas|url=https://www.businessinsider.com/inside-burlington-bunker-britains-secret-underground-city-2017-1|title=Inside Britain's secret underground city built during the Cold War to protect the government from nuclear attack|work=Business Insider|date=8 May 2017|access-date=18 July 2019|archive-date=13 January 2019|archive-url=https://web.archive.org/web/20190113232014/http://uk.businessinsider.com/inside-burlington-bunker-britains-secret-underground-city-2017-1|url-status=live}}</ref>

== Details of shelter construction ==
[[File:Swiss Civil Defense Bunker (15710856390).jpg|thumb|Door of a public fallout shelter in Switzerland (2014).]]
[[File:Big german fire door 1.png|thumb|Large fire door, sealing a fallout and air raid shelter inside the basement parking garage of a hotel in Germany.]]

=== Shielding ===
A basic fallout shelter consists of shields that reduce gamma ray exposure by a factor of 1000. The required shielding can be accomplished with 10 times the [[Radiation protection#Shielding design|thickness]] of any quantity of material capable of cutting gamma ray exposure in half. Shields that reduce gamma ray intensity by 50% (1/2) include {{convert|1|cm|in|1}} of lead, {{convert|6|cm|in|1|abbr=on}} of concrete, {{convert|9|cm|in|1|abbr=on}} of packed earth or {{convert|150|m|ft|sigfig=1}} of air. When multiple thicknesses are built, the shielding multiplies. Thus, a practical fallout shield is ten halving-thicknesses of packed earth, reducing gamma rays by approximately 1024 times (2<sup>10</sup>).<ref>{{cite web|url=http://www.derose.net/steve/guides/emergency/hardened.html|title=Halving-thickness for various materials|work=The Compass DeRose Guide to Emergency Preparedness&nbsp;– Hardened Shelters|access-date=August 15, 2012|archive-date=January 22, 2018|archive-url=https://web.archive.org/web/20180122235733/http://www.derose.net/steve/guides/emergency/hardened.html|url-status=dead}}</ref>

Usually, an expedient purpose-built fallout shelter is a trench; with a strong roof buried by 1&nbsp;m (3&nbsp;ft) of earth. The two ends of the trench have ramps or entrances at right angles to the trench, so that gamma rays cannot enter (they can travel only in straight lines). To make the overburden waterproof (in case of rain), a plastic sheet may be buried a few inches below the surface and held down with rocks or bricks.<ref name=NWSS6>{{cite book|last=Kearny|first=Cresson H|title=Nuclear War Survival Skills|year=1986|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|isbn=0-942487-01-X|pages=37–45|url=http://www.oism.org/nwss/s73p916.htm|quote="The 3-foot thickness of earth shown (or a 2-foot thickness of concrete) will provide an effective barrier, attenuating (absorbing) about 99.9%, of all gamma rays from fallout." "A right-angle turn, either from a vertical or horizontal entry, causes a reduction of about 90%." "...a large piece of 4-mil-thick polyethylene was placed over the mound. This waterproof material served as a "buried roof" after it was covered with more earth."}}</ref>

Blast doors are designed to absorb the shock wave of a nuclear blast, bending and then returning to their original shape.<ref name=lostworlds>{{cite episode|title= Secret U.S. Bunkers|series=[[Lost Worlds (TV series)|Lost Worlds]]|network=The History Channel|date=August 29, 2007|number=18}}</ref>

=== Climate control ===
Dry earth is a reasonably good thermal insulator, but over several weeks of habitation, a shelter will become dangerously hot.<ref name=NWSS7/> The simplest form of effective fan to cool a shelter is a wide, heavy frame with flaps that swing in the shelter's doorway and can be swung from hinges on the ceiling. The flaps open in one direction and close in the other, pumping air. (This is a [[Kearny air pump]], or KAP, named after the inventor, [[Cresson Kearny]].)

Unfiltered air is safe, since the most dangerous fallout has the consistency of sand or finely ground pumice.<ref name=NWSS7/> Such large particles are not easily ingested into the soft tissues of the body, so extensive filters are not required. Any exposure to fine dust is far less hazardous than exposure to the fallout outside the shelter. Dust fine enough to pass the entrance will probably pass through the shelter.<ref name=NWSS7>{{cite book|last=Kearny|first=Cresson H|title=Nuclear War Survival Skills |year= 1986|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|isbn=0-942487-01-X |pages=51–56 |url=http://www.oism.org/nwss/s73p917.htm}}</ref> Some shelters, however, incorporate [[Chemical, biological, radiological, and nuclear|NBC]]-filters for additional protection.

=== Locations ===
Effective public shelters can be the middle floors of some tall buildings or parking structures, or below ground level in most buildings with more than 10 floors. The thickness of the upper floors must form an effective shield, and the windows of the sheltered area must not view fallout-covered ground that is closer than 1.5&nbsp;km (1&nbsp;mi). One of Switzerland's solutions is to use road tunnels passing through the mountains, with some of these shelters being able to protect tens of thousands.<ref name=BBC1>{{cite news|last=Foulkes|first=Imogen|title=Swiss still braced for nuclear war|url=http://news.bbc.co.uk/2/hi/programmes/from_our_own_correspondent/6347519.stm|access-date=August 15, 2012|newspaper=BBC News, Switzerland|date=February 10, 2007}}</ref>

Fallout shelters are not always underground. Above ground buildings with walls and roofs dense enough to afford a meaningful [[Radiation protection#Shielding design|protection factor]] can be used as a fallout shelter.<ref>Monteyne, David. ''Fallout Shelter: Designing for Civil Defense in the Cold War.'' Minneapolis: University of Minnesota, 2011. Print.</ref>

=== Contents ===
A battery-powered radio may be helpful to get reports of fallout patterns and clearance. However, radio and other electronic equipment may be disabled by [[electromagnetic pulse]]. For example, even at the height of the Cold War, [[Electromagnetic pulse#Practical considerations for nuclear EMP|EMP protection]] had been completed for only 125 of the approximately 2,771 radio stations in the United States [[Emergency Broadcast System]]. Also, only 110 of 3,000 existing Emergency Operating Centers had been protected against EMP effects.<ref name=NWSS4>{{cite book|last=Kearny|first=Cresson H|title=Nuclear War Survival Skills|year=1986|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|isbn=0-942487-01-X|pages=24|url=http://www.oism.org/nwss/s73p914.htm}}</ref> The Emergency Broadcast System has since been supplanted in the United States by the [[Emergency Alert System]].

The reference ''Nuclear War Survival Skills'' includes the following supplies in a list of "Minimum Pre-Crisis Preparations": one or more shovels, a pick, a bow-saw with an extra blade, a hammer, and {{convert|4|mil|mm|order=flip|1|abbr=on}} polyethylene film (also any necessary nails, wire, etc.); a homemade shelter-ventilating pump (a [[Kearny air pump|KAP]]); large containers for water; a plastic bottle of sodium hypochlorite bleach; one or two [[Kearny Fallout Meter|KFMs]] (Kearny fallout meters) and the knowledge to operate them; at least a 2-week supply of compact, nonperishable food; an efficient portable stove; wooden matches in a waterproof container; essential containers and utensils for storing, transporting, and cooking food; a hose-vented {{convert|5|usgal|L|order=flip|sigfig=1}} can, with heavy plastic bags for liners, for use as a toilet; tampons; insect screen and fly bait; any special medications needed by family members; pure [[potassium iodide]], a {{convert|2|usfloz|mL|order=flip|sigfig=1|abbr=on}} bottle, and a medicine dropper; a first-aid kit and a tube of antibiotic ointment; long-burning candles (with small wicks) sufficient for at least 14 nights; an [[Nuclear War Survival Skills#Light|oil lamp]]; a flashlight and extra batteries; and a transistor radio with extra batteries and a metal box to protect it from electromagnetic pulse.<ref name=NWSS17>{{cite book|last=Kearny|first=Cresson H|title=Nuclear War Survival Skills|year=1986|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|isbn=0-942487-01-X|pages=133–134|url=http://www.oism.org/nwss/s73p927.htm}}</ref>

Inhabitants should have water on hand, {{convert|1|-|2|usgal|L|order=flip|sigfig=1}} per person per day. Water stored in bulk containers requires less space than water stored in smaller bottles.<ref>{{cite journal|last=Hammes|first=JA|title=Fallout shelter survival research|journal=Journal of Clinical Psychology|year=1966|volume=22|issue=3|pages=154–159|doi=10.1002/1097-4679(196607)22:3<344::aid-jclp2270220330>3.0.co;2-v|pmid=5917900}}</ref>

==== Kearny fallout meter ====
Commercially made [[Geiger counter]]s are expensive and require frequent calibration. It is possible to construct an [[electroscope#Gold-leaf electroscope|electrometer]]-type radiation meter called the [[Kearny fallout meter]], which does not require batteries or professional calibration, from properly-scaled plans with just a coffee can or pail, gypsum board, [[monofilament fishing line]], and aluminum foil.<ref name=A>{{cite book|last=Kearny|first=Cresson H|title=The KFM, A Homemade Yet Accurate and Dependable Fallout Meter|year=1978|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|url=http://www.ornl.gov/~webworks/cppr/y2001/rpt/112538.pdf|url-status=dead|archive-url=https://web.archive.org/web/20040325094514/http://www.ornl.gov/~webworks/cppr/y2001/rpt/112538.pdf|archive-date=March 25, 2004|df=mdy-all}}</ref> Plans are freely available in the public domain in the reference ''Nuclear War Survival Skills'' by [[Cresson Kearny]].<ref name=NWSS11>{{cite book|last=Kearny|first=Cresson H|title=Nuclear War Survival Skills|year=1986|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|isbn=0-942487-01-X|pages=95–100|url=http://www.oism.org/nwss/s73p921.htm}}</ref>

== Use ==
[[File:About Fallout 1955.webm|thumb|''"About Fallout"'' (1955) - Official U.S. Civil Defense information film reel.]]
Inhabitants should plan to remain sheltered for at least two weeks (with an hour out at the end of the first week&nbsp;– see Swiss Civil Defense guidelines), then work outside for gradually increasing amounts of time, to four hours a day at three weeks. The normal work is to sweep or wash fallout into shallow trenches to decontaminate the area. They should sleep in a shelter for several months. Evacuation at three weeks is recommended by official authorities.{{citation needed|date=August 2012}}

If available, inhabitants may take [[potassium iodide]] at the rate of 130&nbsp;mg/day per adult (65&nbsp;mg/day per child) as an additional measure to protect the thyroid gland from the uptake of dangerous radioactive iodine, a component of most fallout and reactor waste.<ref name=NWSS14>{{cite book|last=Kearny|first=Cresson H|title=Nuclear War Survival Skills|year=1986|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|isbn=0-942487-01-X|pages=111–117|url=http://www.oism.org/nwss/s73p924.htm}}</ref>

{| style="float:right; clear:right; margin-left:1.2em;"
|-
|[[File:Alfa beta gamma radiation penetration.svg|thumb|Relative abilities of three different types of [[ionizing radiation]] to penetrate solid matter.]]
|-
|[[File:Protectionfactorchernobyl10cm.png|thumb|The protection factor provided by '''10&nbsp;cm of concrete shielding''' where the source is the idealised Chernobyl fallout.<ref name=OECD>Note that this image was drawn using data from the [http://atom.kaeri.re.kr/ton/nuc6.html ''OECD report''] and the second edition of ''The Radiochemical Manual''</ref>]]
|-
|[[File:Protectionfactorchernobyl20cm.png|thumb|The protection factor provided by '''20&nbsp;cm of concrete shielding''' where the source is the idealised Chernobyl fallout.<ref name=OECD/>]]
|-
|[[File:Protectionfactorchernobyl30cm.png|thumb|The protection factor provided by '''30&nbsp;cm of concrete shielding''' where the source is the idealised Chernobyl fallout.<ref name=OECD/>]]
|-
|[[File:Relativedoseratesnormalisedforday1.png|thumb|Calculated relative gamma dose rates from atomic bomb and Chernobyl fallout]]
|}

== Different types of radiation emitted by fallout ==

=== Alpha (α) ===
In the vast majority of accidents, and in all [[atomic bomb]] blasts, the threat due to beta and gamma emitters is greater than that posed by the alpha emitters in the fallout. Alpha particles are identical to a helium-4 nucleus (two protons and two neutrons), and travel at speeds in excess of 5% of the speed of light. [[Alpha particle]]s have little penetrating power; most cannot penetrate through human skin. Avoiding direct exposure with fallout particles will prevent injury from alpha radiation.<ref name=NWSSC>{{cite book|last=Kearny|first=Cresson H|title=Nuclear War Survival Skills|year=1986|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|isbn=0-942487-01-X|pages=45|url=http://www.oism.org/nwss/s73p916.htm}}</ref>

=== Beta (β) ===
[[Beta particle|Beta radiation]] consists of particles (high-speed electrons) given off by some fallout. Most beta particles cannot penetrate more than about {{convert|3|m|ft|0}} of air or about {{convert|1/8|in|mm|0|order=flip|abbr=on}} of water, wood, or human body tissue; or a sheet of aluminum foil. Avoiding direct exposure with fallout particles will prevent most injuries from beta radiation.<ref name=NWSSD/>

The primary dangers associated with beta radiation are internal exposure from ingested fallout particles and beta burns from fallout particles no more than a few days old. [[Beta burn]]s can result from contact with highly radioactive particles on bare skin; ordinary clothing separating fresh fallout particles from the skin can provide significant shielding.<ref name=NWSSD>{{cite book |last=Kearny |first=Cresson H |title=Nuclear War Survival Skills |year=1986 |publisher=Oak Ridge National Laboratory |location=Oak Ridge, TN |isbn=0-942487-01-X |page=44 |url=http://www.oism.org/nwss/s73p916.htm}}</ref>

=== Gamma (γ) ===
[[Gamma ray|Gamma radiation]] penetrates further through matter than alpha or beta radiation. Most of the design of a typical fallout shelter is intended to protect against gamma [[electromagnetic radiation|rays]]. Gamma rays are better absorbed by materials with high atomic numbers and high density, although neither effect is important compared to the total mass per area in the path of the gamma ray. Thus, lead is only modestly better as a gamma shield than an equal mass of another shielding material such as aluminum, concrete, water or soil.

Some gamma radiation from fallout will penetrate into even the best shelters. However, the radiation dose received while inside a shelter can be significantly reduced with proper shielding. Ten halving thicknesses of a given material can reduce gamma exposure to less than {{frac|1|1000}} of unshielded exposure.<ref name=NWSSE>{{cite book |last=Kearny |first=Cresson H |title=Nuclear War Survival Skills |year=1986 |publisher=Oak Ridge National Laboratory |location=Oak Ridge, TN |isbn=0-942487-01-X |pages=11–20 |url=http://www.oism.org/nwss/s73p912.htm}}</ref>

== Weapons versus nuclear accident fallout ==
The bulk of the [[radioactivity]] in nuclear accident fallout is more long-lived than that in weapons fallout. A good table of the [[nuclide]]s, such as that provided by the [[Korean Atomic Energy Research Institute]], includes the [[Nuclear fission|fission]] yields of the different nuclides. From this data it is possible to calculate the isotopic mixture in the fallout (due to [[fission products]] in bomb fallout).{{citation needed|date=August 2012}}

== Other matters and simple improvements ==
While a person's home may not be a purpose-made shelter, it could be thought of as one if measures are taken to improve the degree of [[Radiation protection|fallout protection]].

=== Measures to lower the beta dose ===
The main threat of [[Radiation#Beta|beta radiation]] exposure comes from ''[[hot particle]]s'' in contact with or close to the skin of a person. Also, swallowed or inhaled hot particles could cause [[beta burn]]s. As it is important to avoid bringing hot particles into the shelter, one option is to remove one's outer clothing, or follow other [[human decontamination|decontamination procedures]], on entry. Fallout particles will cease to be radioactive enough to cause beta burns within a few days following a nuclear explosion. The danger of gamma radiation will persist for far longer than the threat of beta burns in areas with heavy fallout exposure.<ref name=NWSSA>{{cite book|last=Kearny|first=Cresson H|title=Nuclear War Survival Skills|year=1986|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|isbn=0-942487-01-X|pages=131|url=http://www.oism.org/nwss/s73p926.htm#Message2481}}</ref>

=== Measures to lower the gamma dose rate ===
The gamma dose rate due to the contamination brought into the shelter on the clothing of a person is likely to be small (by wartime standards) compared to [[Radiation#Gamma|gamma radiation]] that penetrates through the walls of the shelter.<ref name=NWSSA/> The following measures can be taken to reduce the amount of gamma radiation entering the shelter:
* Roofs and gutters can be cleaned to lower the dose rate in the house.
* The top inch of soil in the area near the house can be either removed or dug up and mixed with the [[subsoil]]. This reduces the dose rate as the gamma rays have to pass through the topsoil before they can irradiate anything above.
* Nearby roads can be rinsed and washed down to remove dust and debris; the fallout would collect in the sewers and gutters for easier disposal. In [[Kyiv]] after the [[Chernobyl accident]] a program of road washing was used to control the spread of radioactivity.
* Windows can be bricked up, or the sill raised to reduce the hole in the shielding formed by the wall.
* Gaps in the shielding can be blocked using containers of water. While water has a much lower density than that of lead, it is still able to shield some gamma rays.
* Earth (or other dense material) can be heaped up against the exposed walls of the building; this forces the gamma rays to pass through a thicker layer of shielding before entering the house.
* Nearby trees can be removed to reduce the dose due to fallout which is on the branches and leaves. It has been suggested by the US government that a fallout shelter should not be dug close to trees for this reason.<ref name=NWSSB>{{cite book|last=Kearny|first=Cresson H|title=Nuclear War Survival Skills|year=1986|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|isbn=0-942487-01-X|pages=39|url=http://www.oism.org/nwss/s73p916.htm}}</ref>

== Fallout shelters in popular culture ==
[[File:CivilDefense square.svg|thumb|The international distinctive sign of civil defense personnel and infrastructures.]]

Fallout shelters feature prominently in the [[Robert A. Heinlein]] novel ''[[Farnham's Freehold]]'' (Heinlein built a fairly extensive shelter near his home in [[Colorado Springs, Colorado|Colorado Springs]] in 1963),<ref>{{Cite web|url=http://www.nitrosyncretic.com/rah/pm652-art-hi.html|archiveurl=https://web.archive.org/web/20100106154437/http://www.nitrosyncretic.com/rah/pm652-art-hi.html|url-status=dead|title=site: Robert A. Heinlein - Archives - PM 6/52 Article|archivedate=January 6, 2010|website=www.nitrosyncretic.com}}</ref> ''Pulling Through'' by [[Dean Ing]], ''[[A Canticle for Leibowitz]]'' by [[Walter M. Miller]] and ''[[Earth (Brin novel)|Earth]]'' by [[David Brin]].

The 1961 ''[[The Twilight Zone (1959 TV series)|Twilight Zone]]'' episode "[[The Shelter (The Twilight Zone)|The Shelter]]", from a [[Rod Serling]] script, deals with the consequences of actually using a shelter. Another episode of the series called "[[One More Pallbearer]]" featured a fallout shelter owned by a millionaire. The [[The Twilight Zone (1985 TV series)|1985 adaption of the series]] had the episode "[[Shelter Skelter]]" that featured a fallout shelter.

In 1973, British rock band [[The Who]] called their tour Fallout Shelter.

In the ''[[Only Fools and Horses]]'' episode "[[The Russians Are Coming (Only Fools and Horses)|The Russians are Coming]]", aired in 1981, Derek Trotter buys a lead fallout shelter, then decides to construct it in fear of an impending nuclear war caused by the Soviet Union.

In 1999, the film ''[[Blast from the Past (film)|Blast from the Past]]'' was released. It is a [[romantic comedy]] film about a [[Nuclear physics|nuclear physicist]], his wife, and son that enter a well-equipped, spacious fallout shelter during the 1962 [[Cuban Missile Crisis]]. They do not emerge until 35 years later, in 1997. The film shows their reaction to contemporary society.

The [[Fallout series|''Fallout'' series]] of computer games depicts the remains of human civilization after an immensely destructive global nuclear war; the United States of America had built underground fallout shelters known as vaults, that were advertised to protect the population against a nuclear attack, but almost all of them were in fact meant to lure [[Human subject research|subjects]] for long-term [[Unethical human experimentation|human experimentation]].

''[[Paranoia (role-playing game)|Paranoia]]'', a role-playing game, takes place in a city-sized fallout shelter, which has become ruled by an insane computer.

An episode of the sitcom ''[[Malcolm in the Middle]]'' features a subplot revolving around Reese and Dewey discovering a previously unknown fallout shelter in their backyard and trapping their father Hal in it, who soon becomes smitten with the shelter's 1960s decor.

The ''[[Metro 2033 (novel)|Metro 2033]]'' book series by Russian author [[Dmitry Glukhovsky]] depicts survivors' life in the subway systems below Moscow and Saint-Petersburg after a nuclear exchange between the Russian Federation and the United States of America.

Fallout shelters are often featured on the reality television show ''[[Doomsday Preppers]]''.<ref>{{cite web| url = http://channel.nationalgeographic.com/doomsday-preppers/articles/get-prepped-shelter/| archive-url = https://web.archive.org/web/20150401233537/http://channel.nationalgeographic.com/doomsday-preppers/articles/get-prepped-shelter/| url-status = dead| archive-date = April 1, 2015| title = Shelter - Doomsday Preppers Article - National Geographic Channel}}</ref>

The [[Silo (series)|''Silo'' series]] of novellas by [[Hugh Howey]] feature extensive fallout-style shelters that protect the inhabitants from an initially unknown disaster.

The 2019 US film ''[[The Tomorrow Man]]'' centers around a reclusive man whose main preoccupation is tending to his in-home fallout shelter and the conspiracy theories that could put it to use.

== See also ==
{{colbegin|colwidth=}}
* [[Abo Elementary School]]
* [[Ark Two Shelter]]
* [[Blast shelter]]
* [[Bomb shelter]]
* [[Bunker]]
* [[Bruce D. Clayton]], author of ''Fallout Survival'' and ''Life After Doomsday''
* [[Collective protection]]
* [[Command center]]
* [[CONELRAD]]
* [[Continuity of government]]
* [[Project Greek Island]]
* [[Vivos (underground shelter)]]
{{Div col end}}
'''Nation specific:'''
{{colbegin}}
* [[Central Government War Headquarters]], The UKs Gov. War Headquarters at Corsham, Wiltshire.
* [[Diefenbunker]]
* [[HANDEL]], UK's former national attack warning system
{{Div col end}}

'''General:'''
{{colbegin}}
* [[Fission product]]
* [[Retreat (survivalism)]]
* [[Sonnenberg Tunnel]]
* [[Survivalism]]
{{Div col end}}
'''Publications:'''
{{colbegin}}
* ''[[Fallout Protection]]''
* ''[[Survival Under Atomic Attack]]''
* ''[[Nuclear War Survival Skills]]''
{{Div col end}}

== Notes and references ==
{{Reflist|30em}}

==Further reading==
* Rose, Kenneth D., ''One Nation Underground:  The Fallout Shelter in American Culture'', [[New York University Press]] (2004), {{ISBN|978-0814775233}}
* [https://azer.com/aiweb/categories/magazine/ai143_folder/143_articles/143_letters_nuclear.html Readers Forum: Nuclear Fallout Shelters 50 Years Ago (Greeneville, Tennessee)] by Henry Samples (1947–2024), AZER.com, in ''Azerbaijan International'', Vol. 14:3 (Autumn 2006), pp.&nbsp;12–13.

== External links ==
{{Commons category|Fallout shelters}}
* [http://www.oism.org/nwss/ Nuclear War Survival Skills]

{{fortifications}}
{{Man-made and man-related Subterranea}}
{{Civil defence}}

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{{DEFAULTSORT:Fallout Shelter}}
[[Category:Air raid shelters]]
[[Category:Cold War sites]]
[[Category:Nuclear warfare]]
[[Category:Radioactivity]]
[[Category:Radiobiology]]
[[Category:Subterranea (geography)]]
[[Category:Survivalism]]
[[Category:Radiation protection]]
[[Category:Nuclear fallout]]