duck and cover

{{blockquote|Dropping immediately and covering exposed skin provide[s] protection against blast and thermal effects ... Immediately drop facedown. A log, a large rock, or any depression in the earth's surface provides some protection. Close eyes. Protect exposed skin from heat by putting hands and arms under or near the body and keeping the helmet on. Remain facedown until the blast wave passes and debris stops falling. Stay calm, check for injury, check weapons and equipment damage, and prepare to continue the mission.|US Army field manual FM 3–4 Chapter 4.{{Cite book|title=Nuclear, Biological, Chemical Protection Field Manual (FM 3-4)|publisher=US Department of Defense|location=Washington, DC|chapter=Nuclear Protection|chapter-url=http://www.globalsecurity.org/wmd/library/policy/army/fm/3-4/Ch4.htm|archive-url=https://web.archive.org/web/20130313223255/http://www.globalsecurity.org/wmd/library/policy/army/fm/3-4/Ch4.htm|archive-date=13 March 2013|date=21 February 1996}}}}

Immediately after one sees the first flash of intense heat and light of the developing nuclear fireball, one should stop, get under some cover and drop/duck to the ground. There, one should assume a prone-like position, lying face-down, and to afford protection against the continuing heat of the explosion further cover exposed skin and the back of one's head with one's clothes; or, if no excess cover or cloth is available, one should cover the back of one's head and neck with one's hands.

Similar instructions, as presented in the Duck and Cover film, are contained in the British 1964 public information film Civil Defence Information Bulletin No. 5{{cite web|url=https://www.youtube.com/watch?v=PgqhaZmPFRg|title=Civil Defence Bulletin – No. 5|publisher=YouTube|date=25 December 2006|access-date=11 March 2013|type=video}}{{cbignore}}{{Dead Youtube links|date=February 2022}} and in the 1980s Protect and Survive public information series.{{cite web|url=https://www.youtube.com/watch?v=m6U9T3R3EQg&t=28m27s |archive-url=https://ghostarchive.org/varchive/youtube/20211221/m6U9T3R3EQg |archive-date=2021-12-21 |url-status=live|title=Protect and Survive: Action After Warnings 28:27–28:50 (part 10)|type=video|publisher=YouTube|date=9 December 2012|access-date=15 April 2015}}{{cbignore}} Children in the Soviet Union likewise received almost identical classes on countermeasures, according to Inside the Kremlin's Cold War authors Zubok and Pleshakov.{{Cite book|url=https://books.google.com/books?id=nHFCKmo2PH8C&q=inkwell&pg=PA122|title=One Nation Underground: The Fallout Shelter in American Culture|first=Kenneth D.|last=Rose|date=1 May 2004|publisher=NYU Press|via=Google Books|isbn=9780814775233}}

In U.S. Army training, soldiers are taught to fall down immediately and cover their face and hands in much the same way as is described above.

In the classroom scene of the film, the rapid employment of school desks, as an improvised shelter following the awareness of the initial light flash, is a countermeasure primarily to offer protection from potential ballistic window glass lacerations when the slower moving blast wave arrived. However, in higher blast pressure zones, where partial-to-total building collapse may occur, it would also serve a similar role to that borne out from experience in urban search and rescue, where voids under the debris of collapsed buildings are common places for survivors to be found. More rigid examples of void-forming-tables to shelter under include the "Morrison indoor shelter", which was widely distributed by the millions in Britain as a protective measure against building collapse, brought about by blast pressures generated during the conventional bombing of cities in World War II.{{cite web|url=http://www.rafmuseum.org.uk/research/online-exhibitions/history-of-the-battle-of-britain/air-raid-shelter-protection.aspx|title=Air Raid Shelter Protection - History of the Battle of Britain - Exhibitions & Displays - Research - RAF Museum}}{{cite web|url=http://spartacus-educational.com/2WWmorrisonshelter.htm|title=Morrison Shelters}}{{cite web|url=http://mashable.com/2015/07/24/wwii-backyard-bunkers/|title=How families lived in their WWII backyard bomb bunkers|first=Alex|last=Arbuckle|website=Mashable|date=24 July 2015}}{{cite web|url=http://www.military-history.org/articles/air-raid-shelters.htm|title=Air Raid Shelters: A short history of British air-raid shelters WW1 and WW2|date=1 October 2010}}{{efn |1=The building in which the table/Morrison shelter is located was advised to be as free from combustible materials as possible, as the potential of a fire in the debris, post-collapse, would be fatal to those sheltering inside.}}

Under the conditions where some warning is given, one is advised to find the nearest bomb shelter, or if one could not be found, any well-built building to stay and shelter in place. Sheltering is, as depicted in the film, also the final phase of the "duck and cover" countermeasure in the surprise attack scenario.

The "duck and cover" countermeasure could save thousands. This is because people, being naturally inquisitive, would instead run to windows to try to locate the source of the immensely bright flash generated at the instant of the explosion. During this time, unbeknownst to them, the slower moving blast wave,{{cite web |url=http://www.acq.osd.mil/ncbdp/nm/nm_book_5_11/appendix_F.htm |title=The Nuclear Matters Handbook |access-date=2013-11-30 |year=1991 |publisher=Assistant Secretary of Defense for Nuclear, Chemical, and Biological Defense Programs |quote=Initially, this blast wave moves at several times the speed of sound, but it quickly slows to a point at which the leading edge of the blast wave is traveling at the speed of sound, and it continues at this speed as it moves farther away from ground zero |archive-url=https://web.archive.org/web/20130302091606/http://www.acq.osd.mil/ncbdp/nm/nm_book_5_11/appendix_F.htm |archive-date=2013-03-02 }}{{cite web |url=http://ocw.nd.edu/physics/nuclear-warfare/notes/lecture-14 |title=Nuclear Warfare Lecture 14 by Professor Grant J. Matthews of University of Notre Dame OpenCourseWare. Mechanical Shock velocity equation |archive-url=https://web.archive.org/web/20131219010502/http://ocw.nd.edu/physics/nuclear-warfare/notes/lecture-14 |archive-date=December 19, 2013 }} would be rapidly advancing toward their position, only to arrive and cause the window glass to implode, shredding onlookers.{{cite web|url=http://goodnewsnuke.com/|title=The Good News About Nuclear Destruction|quote=...most can save themselves by immediately employing the 'Duck & Cover' tactic, rather than just allowing an impulsive rush to the nearest windows to see what that 'bright flash' was across town, just-in-time to be shredded by the glass imploding inward from that delayed shock wave blast.|last=Conner|first=Shane|website=KI4U|publisher=KI4U, Inc.|access-date=15 April 2015|archive-url=https://web.archive.org/web/20150509135506/http://www.goodnewsnuke.com/|archive-date=9 May 2015}} In the testimony of Dr. Hiroshi Sawachika, although he was sufficiently far away from the Hiroshima bomb himself and was not behind a pane of window glass when the blast wave arrived, those in his company who were had serious blast injury wounds, with broken glass and pieces of wood stuck into them.{{cite web |url=http://history.hanover.edu/courses/excerpts/111hiroshima.html|title=Hiroshima Survivors' Testimony – Testimony of Hiroshi Sawachika, 1986|access-date=15 April 2015|publisher=Hanover College History Department|last=Sawachika|first=Hiroshi}} The Hiroshima and Nagasaki explosions were fission bombs which are much weaker than thermonuclear devices, also known as "H-bombs", by a factor of 1000 or more. Two Japanese cities, Hiroshima and Nagasaki, were hit by bombs in 1945 that had a force equivalent to 16 kilotons (16,000 tons) and 21 kilotons of TNT, respectively. On 1 November 1952, the first hydrogen bomb was exploded by the United States at Enewetak atoll in the Marshall Islands. " Ivy Mike", codename for the bomb, released energy equal to around 10 megatons — or 10 million tons of TNT. {{cite web | url=https://www.businessinsider.com/how-hydrogen-bombs-work-invented-edward-teller-2023-8?op=1 | title=How hydrogen bombs work and why they were created after WWII despite being more powerful than atomic bombs | website=Business Insider }} In 1961, the Tsar bomb was exploded by the Soviet Union, producing an explosion with a mass of 50 megatons— which was about 1,500 times more than the combined force of the atomic bombs fired on Hiroshima and Nagasaki. {{cite web | url=https://www.businessinsider.com/how-hydrogen-bombs-work-invented-edward-teller-2023-8?op=1 | title=How hydrogen bombs work and why they were created after WWII despite being more powerful than atomic bombs | website=Business Insider }}

Similar advice to "duck and cover" is given in many situations where structural destabilization or flying debris may be expected, such as during an earthquake or tornado. At a sufficient distance from a nuclear explosion, the blast wave produces similar results to these natural phenomena, so similar countermeasures are taken. In areas where earthquakes are common, a countermeasure known as "Drop, Cover, and Hold On!" is practiced.{{Cite web|url=http://www.shakeout.org/dropcoverholdon/|title=Great ShakeOut Earthquake Drills - Drop, Cover, and Hold On|access-date=15 April 2015|website=ShakeOut|publisher=Southern California Earthquake Center}}{{Cite web|url=http://www.earthquakecountry.info/dropcoverholdon/|title=How to Protect Yourself During an Earthquake... Drop, Cover, and Hold On!|access-date=15 April 2015|website=Earthquake Country Alliance|archive-date=19 January 2016|archive-url=https://web.archive.org/web/20160119200720/http://www.earthquakecountry.info/dropcoverholdon/|url-status=dead}}{{Cite web|url=http://www.cusec.org/earthquake-safety/drop-cover-a-hold.html|title=Drop, Cover, & Hold|access-date=15 April 2015|website=CUSEC|publisher=Central United States Earthquake Consortium|archive-url=https://web.archive.org/web/20150417000807/http://www.cusec.org/earthquake-safety/drop-cover-a-hold.html|archive-date=17 April 2015}} Likewise, in tornado-prone areas of the United States, especially those within Tornado Alley, tornado drills involve teaching children to move closer to the floor and to cover the backs of their heads to prevent injury from flying debris.{{cite web|url=http://www.floridadisaster.org/hwa03/drill.htm |title=Florida Disaster |date=2007-02-05 |access-date=2013-03-11 |archive-url=https://web.archive.org/web/20070205185900/http://www.floridadisaster.org/hwa03/drill.htm |archive-date=February 5, 2007 }}{{cite web |url=http://www.pisd.edu/about.us/safety/disaster.policy.shtml |title=Plano, Texas ISD |publisher=Pisd.edu |access-date=2013-03-11 |archive-url=https://web.archive.org/web/20130514044534/http://pisd.edu/about.us/safety/disaster.policy.shtml |archive-date=2013-05-14 }} Some US states also practice annual emergency tornado drills.{{Cite web|url=http://www.vaemergency.gov/readyvirginia/stay-informed/tornado/conductdrill|title=Tornado Drill|access-date=15 April 2015|website=VA Emergency|publisher=Virginia Department of Emergency Management|archive-url=https://web.archive.org/web/20150407020604/http://www.vaemergency.gov/readyvirginia/stay-informed/tornado/conductdrill|archive-date=7 April 2015}}{{Cite web|url=http://www.scemd.org/component/content/article/21-home-page/public-information/166-south-carolina-severe-weather-awareness-week|title=South Carolina Severe Weather Awareness Week|access-date=15 April 2015|website=SCEMD|publisher=South Carolina Emergency Management Division|archive-url=https://web.archive.org/web/20150330062105/http://www.scemd.org/component/content/article/21-home-page/public-information/166-south-carolina-severe-weather-awareness-week|archive-date=30 March 2015}}

The dangers of viewing explosions behind window glass were known of before the Atomic Age began, being a common source of injury and death from large chemical explosions. The Halifax Explosion of 1917, an ammunition ship exploding with the energy of roughly 2.9 kilotons of TNT,Ruffman, Alan and Howell, Colin D. (edited by). Ground Zero: A Reassessment of the 1917 Explosion in Halifax Harbour (1994, Nimbus Publishing), p.276. injured the eyes and faces of hundreds of people who stayed behind and looked out of their windows after seeing a bright flash, with 200 blinded by broken glass when the slower moving blast arrived.{{cite web|url=http://www.engr.psu.edu/cde/Short/MPS_course/newpage/Exp-Dam-Ass-1.pdf|archive-url=https://web.archive.org/web/20121224172332/http://www.engr.psu.edu/cde/Short/MPS_course/newpage/Exp-Dam-Ass-1.pdf|archive-date=24 December 2012|title=Explosion damage assessment |date=24 December 2012}} Every window in the city of Halifax, Nova Scotia, was shattered in this catastrophe of human error.{{cite journal |last1=McAlister |first1=Chryssa N. |last2=Murray |first2=T. Jock |last3=Lakosha |first3=Hesham |last4=Maxner |first4=Charles E. |title=The Halifax disaster (1917): eye injuries and their care |journal=British Journal of Ophthalmology |date=June 2007 |volume=91 |number=6 |pages=832–5 |doi=10.1136/bjo.2006.113878 |pmc=1955605 |pmid=17510478}}

In the Record of the "Nagasaki A-bomb War Disaster",http://www.gensuikin.org/english/photo.html {{Webarchive|url=https://web.archive.org/web/20071029144153/http://www.gensuikin.org/english/photo.html |date=2007-10-29 }} Photographs of

Hiroshima and Nagasaki those close to the hypocenter (Matsuyama township), were described as all having been killed, with the exception of "a child who was in an air-raid shelter." A little further away, Professor Seiki of Nagasaki Medical School Hospital was building an air-raid dugout 400 m from the hypocenter of the detonation and survived.{{cite web|url=http://www.nukefallout.com/nagasaki.html|title=The Atomic Bombing of Nagasaki}} Chimoto-san, who was atop a distant hill that creates the valley in which Nagasaki is located, performed the similar "hit the deck" maneuver upon seeing the bomb drop, which was notably prior to the detonation. However despite having these few seconds of relatively unique warning, he did not stay on the ground for long enough after the flash subsided, and received some translational injuries due to prematurely standing-up again, at which point the slower moving blast wave swept past him and carried him with it for a few meters.

According to the 1946 book Hiroshima and other books which cover both bombings,{{cite book|title = Nine Who Survived Hiroshima and Nagasaki: Personal Experiences of Nine Men Who Lived through both Atomic Bombings |date = January 1, 1957|first = Robert |last = Trumbull|pages =25,28,61,101,109,119}} in the days between the atomic bombings of Hiroshima and Nagasaki, some survivors of the first bombing went to Nagasaki and taught others about ducking after the atomic flash and informed them about the particularly dangerous threat of imploding window glass.{{usurped|1=[https://web.archive.org/web/20161229163919/https://ke.army.mil/bordeninstitute/published_volumes/nuclearwarfare/chapter9/chapter9.pdf Psychological factors in nuclear warfare, Borden Institute p. 185.]}} As a result of this and other factors, far fewer died in the initial blast at Nagasaki as compared to those who were not taught to duck and cover. The general population however was not warned of the heat or blast danger following an atomic flash, due to the new and unknown nature of the atomic bomb. Many people in Hiroshima and Nagasaki died while searching the skies, curious to locate the source of the brilliant flash.

When people are indoors, running to windows to investigate the source of bright flashes in the sky still remains a common and natural response to experiencing a bright flash. Thus, although the advice to duck and cover is over half a century old, ballistic glass lacerations caused the majority of the 1000 human injuries following the Chelyabinsk meteor air burst of 15 February 2013.{{cite web |last1=Heintz |first1=Jim|last2 = Isachenkov|first2 = Vladimir|url=http://www.canada.com/news/Meteor+explodes+over+Russia+Ural+Mountains+injured+shock+wave+blasts+windows/7968297/story.html |title=Meteor explodes over Russia's Ural Mountains; 1,100 injured as shock wave blasts out windows| quote = Emergency Situations Ministry spokesman Vladimir Purgin said many of the injured were cut as they flocked to windows to see what caused the intense flash of light, which momentarily was brighter than the sun |publisher=Canada.com |date=2013-02-15 |archive-url=https://web.archive.org/web/20130221012916/http://www.canada.com/news/Meteor+explodes+over+Russia+Ural+Mountains+injured+shock+wave+blasts+windows/7968297/story.html |archive-date=2013-02-21 }}

This response was also observed among people in the vicinity of Hiroshima and Nagasaki.{{cite web |url=http://www.ki4u.com/goodnews.htm|title=The Good News About Nuclear Destruction|quote=...most can save themselves by immediately employing the 'Duck & Cover' tactic, rather than just allowing an impulsive rush to the nearest windows to see what that 'bright flash' was across town, just-in-time to be shredded by the glass imploding inward from that delayed shock wave blast.|last=Conner|first=Shane|website=KI4U|publisher=KI4U, Inc.|access-date=15 April 2015}}

Image:Bert2.png poster, featuring Bert the Turtle]]

The United States' monopoly on nuclear weapons was broken by the Soviet Union in 1949 when it tested its first nuclear explosive, the RDS-1. With this, many in the US Government, as well as many citizens, perceived that the United States was more vulnerable than it had ever been before. In 1950, during the first big Civil Defense push of the Cold War—and coinciding with the Alert America! initiative to educate Americans on nuclear preparedness,{{cite web |url=http://conelrad.com/books/folio.php?id=P382|title=Alert America!|access-date=15 April 2015|website=Conelrad|publisher=Conelrad.com}} the adult-orientated Survival Under Atomic Attack was published. It contains "duck and cover" or more accurately, cover and then duck advice without using those specific terms in its Six Survival Secrets For Atomic Attacks section. 1. Try to Get Shielded 2. Drop Flat on Ground or Floor 3. Bury Your Face in Your Arms ("crook of your elbow").{{cite web|url=https://archive.org/details/survivalunderato00bost|title=Survival under atomic attack|last=Boston (Mass. Civil Defense Dept|date=1 January 1951|via=Internet Archive}} The child-oriented film Duck and Cover was produced a year later by the Federal Civil Defense Administration in 1951.

Image:SurvivalUnderAtomicAttack.jpg issued in 1950, pre-dated the release of Duck and Cover in 1951-52. The booklet was accompanied by a companion film by the same name.[https://archive.org/details/0838_Survival_Under_Atomic_Attack_E01425_11_23_59_18 Survival Under Atomic Attack 1951 film]]] "Duck and cover" exercises quickly became a part of Civil Defense drills that every US citizen, from children to the elderly,{{dubious|date=August 2015}} was encouraged to practice{{citation needed|date=August 2015}} so that they could be ready in the event of nuclear war.

Education efforts on the effects of nuclear weapons proceeded with stops-and-starts in the US due to competing alternatives. In a once classified, 1950s era, US war game that looked at varying levels of war escalation, warning and pre-emptive attacks in the late 1950s early 1960s, it was estimated that approximately 27 million US citizens would have been saved with civil defense education.{{cite web|url=http://nsarchive.gwu.edu/nukevault/ebb480/docs/doc+10A+1963.pdf|title=National Security Archive - 30+ Years of Freedom of Information Action|website=nsarchive.gwu.edu|access-date=2018-08-27|archive-url=https://web.archive.org/web/20170719141358/http://nsarchive.gwu.edu/nukevault/ebb480/docs/doc%2010A%201963.pdf|archive-date=2017-07-19}} At the time however the cost of a full-scale civil defense program was regarded as lesser in effectiveness, in cost-benefit analysis than a ballistic missile defense (Nike Zeus) system, and as the Soviet adversary was believed to be rapidly increasing their nuclear stockpile, the efficacy of both would begin to enter a diminishing returns trend. When more became known about the cost and limitations of the Nike Zeus system, in the early 1960s the head of the department of defense under president John F. Kennedy,

Robert McNamara, determined the ineffectiveness of the Nike-Zeus system, especially in its benefit-cost ratio compared to other options. For instance, fallout shelters would save more Americans for far less money.{{CN|date=February 2023}}

File:Operation Castle - Nectar - Detonation.ogv produced a yield of 1.69 megatons and was conducted off the coast of Teiter island. Note the distinctive near instantaneous double flash, with the second appearing brighter than the sun,{{cite web |url=https://nsarchive2.gwu.edu//NSAEBB/NSAEBB190/02.pdf |archive-url=https://web.archive.org/web/20170825003209/https://nsarchive2.gwu.edu//NSAEBB/NSAEBB190/02.pdf |archive-date=25 August 2017 |title=Light flash produced by atmospheric Nuclear explosion |date=25 August 2017}} and the blast wave slowly, by comparison, spreading out turning the calm ocean water a frothy white when it arrives. The maximum average nuclear fireball radius is approximately {{convert|1.4|to|1.6|km|abbr=on}}.{{cite web | last=Walker | first=John | author-link=John Walker (programmer) | title=Nuclear Bomb Effects Computer | publisher=Fourmilab | date=June 2005 | access-date=2009-11-22 | url=http://www.fourmilab.ch/cgi-bin/Bombcalc?yield=1690&yunit=1&range=5&runit=0.62137119&rotate=310&imsize=800 }}{{cite web | last=Walker | first=John | author-link=John Walker (programmer) | title=Nuclear Bomb Effects Computer Revised Edition 1962, Based on Data from The Effects of Nuclear Weapons, Revised Edition "The maximum fireball radius presented on the computer is an average between that for air and surface bursts. Thus, the fireball radius for a surface burst is 13 percent larger than that indicated and for an air burst, 13 percent smaller." | publisher=Fourmilab | date=June 2005 | access-date=2009-11-22 | url=http://www.fourmilab.ch/bombcalc/instructions.html}} The outdoor blast and flash burn LD50s would be around 8 and 12 km respectively.{{cite web|url = https://www.remm.nlm.gov/radiationlethality.htm|title = Size of the Incident and Potential Affected Areas|website = REMM: Radiation Emergency Medical Management|publisher = U.S. Department of Health & Human Services|date = 12 January 2016}} This assumes personnel did not take any prompt countermeasures, instead standing still, absorbing the entire light energy emitted over the ≈20 seconds of emission.]]

Within a considerable radius from the surface of the nuclear fireball, 0–3 kilometers—largely depending on the explosion's height, yield and position of personnel—ducking and covering would offer negligible protection against the intense heat, blast and prompt ionizing radiation following a nuclear explosion. Beyond that range, however, many lives would be saved by following the simple advice,{{cite web|url=http://www.acq.osd.mil/ncbdp/nm/nm_book_5_11/appendix_F.htm |title=The Nuclear Matters Handbook |access-date=2013-11-30 |year=1991 |publisher=Assistant Secretary of Defense for Nuclear, Chemical, and Biological Defense Programs |quote=Individuals who sense a blinding white flash and intense heat coming from one direction should immediately fall to the ground and cover their heads with their arms. This provides the highest probability that the air blast will pass overhead without moving them laterally and that debris in the blast wave will not cause impact or puncture injuries. Exposed individuals who are very close to the detonation have no chance of survival. At distances at which a wood frame building can survive, however, exposed individuals significantly increase their chance of survival if they are on the ground when the blast wave arrives and if they remain on the ground until after the negative phase blast wave has moved back toward ground zero |archive-url=https://web.archive.org/web/20130302091606/http://www.acq.osd.mil/ncbdp/nm/nm_book_5_11/appendix_F.htm |archive-date=2013-03-02 }} especially since at that range the main hazard is not from ionizing radiation but from blast injuries and sustaining thermal flash burns to unprotected skin.{{cite web|url=http://www.johnstonsarchive.net/nuclear/nukgr1.gif |title=Range of weapons effects |publisher=Johnstonsarchive.net |access-date=2013-11-30}}{{cite web |url=http://www.webofstories.com/play/54981?o=R |title=Little Boy on Hiroshima |publisher=Web of Stories |access-date=2013-11-30 |type=video |last=Christy |first=Robert F. |author-link=Robert F. Christy|archive-url=https://archive.today/20130901131934/http://www.webofstories.com/play/robert.christy/13;jsessionid=A169C68887C651CCD55CFD5F5AB5D0D1|archive-date=1 September 2013}} Weapon designer Robert Christy discussing scaling laws, that is, how injuries from ionizing radiation do not scale in lock step with the range of thermal flash injuries, especially as higher and higher yield nuclear weapons are used.{{cite web |url = http://www3.nd.edu/~nsl/Lectures/phys205/pdf/Nuclear_Warfare_9.pdf |title = Nuclear Warfare Lecture 9 |first = Grant J. |last = Matthews |publisher = University of Notre Dame OpenCourseWare |page = 3 |access-date = 2013-08-25 |archive-date = 2013-11-26 |archive-url = https://web.archive.org/web/20131126220402/http://www3.nd.edu/~nsl/Lectures/phys205/pdf/Nuclear_Warfare_9.pdf |url-status = dead }} negligible. Meaning that if one were close enough to get a harmful dose of radiation from a generic 1 megaton weapon, one would very likely die from blast effects alone at that proximity. Furthermore, following the bright flash of light of the nuclear fireball, the explosion's blast wave would take from first light, 7 to 10 seconds to reach a person standing 3 km from the surface of the nuclear fireball, with the exact time of arrival being dependent on the speed of sound in air in their area.{{cite book|last1=Needham|first1=Charles E.|chapter=Scaling Blast Parameters|title=Blast waves|pages=157–169|date=2010|publisher=Springer Verlag|location=Heidelberg|isbn=978-3-642-05288-0|doi=10.1007/978-3-642-05288-0_12}} The time delay between the moment of an explosion's flash and the arrival of the slower moving blast wave is analogous to the commonly experienced time delay between the observation of a flash of lightning and the arrival of thunder during a lightning storm, thus at the distances that the advice would be most effective, there would be more than ample amounts of time to take the prompt countermeasure of 'duck and cover' against the blast's direct effects and flying debris.{{cite web|url = http://www.remm.nlm.gov/PlanningGuidanceNuclearDetonation.pdf|title = Planning Guidance for Response to a Nuclear Detonation|publisher = National Library of Medicine|access-date = 2013-11-30|edition = 2nd|date = June 2010}} For very large explosions it can take 30 seconds or more, after the silent moment of flash, for a potentially dangerous blast wave over-pressure to arrive at, or hit, one's position.{{cite web|url=http://www.ready.gov/nuclear-blast |title=Nuclear Blast |publisher=Ready.gov |date=2013-04-17 |access-date=2013-11-30}}

The graphs of lethal ranges of weapon effects as a function of yield, that are commonly encountered, are the unobstructed "open air", or "free air" ranges that assume among other things, a perfectly level target area, no passive shielding such as attenuating effects from urban terrain masking, e.g. skyscraper shadowing, and so on. Therefore, they are thus considered to present an overestimate of the lethal ranges that would be encountered in an urban setting in the real world,{{cite web|url=http://www.usuhs.mil/afrrianniversary/events/rcsymposium/pdf/Millage.pdf|archive-url=https://web.archive.org/web/20110706161001/http://www.usuhs.mil/afrrianniversary/events/rcsymposium/pdf/Millage.pdf|archive-date=6 July 2011|title=Modeling the Effects of Nuclear Weapons in an Urban Setting |date=6 July 2011}} with this being most evident following a ground burst with explosive yield similar to first generation nuclear weapons.{{cite web |url=https://e-reports-ext.llnl.gov/pdf/348428.pdf |title=UCRL-TR-231593. Thermal Radiation from Nuclear. Detonations in Urban. Environments. R. E. Marrs, W. C. Moss, B. Whitlock. June 7, 2007}}

File:Hiroshima Resthouse 2008 01.JPG, the basement of which Eizo Nomura was in on August 6, 1945 when Little Boy exploded overhead. The building was built as a kimono shop in 1929 and was one of the "about 50" other "fair", or moderately strong, reinforced concrete buildings in central Hiroshima that remained standing following the blast and firestorm and in good structural condition, due to having a high percentage of window area which relieved blast pressure on the structural frames.{{cite book |chapter-url=http://avalon.law.yale.edu/20th_century/mp09.asp |title=The Atomic Bombings of Hiroshima and Nagasaki |chapter=Chapter 9 - General Description of Damage Caused by the Atomic Explosions |quote=In Hiroshima almost everything up to about one mile from X was completely destroyed, except for a small number (about 50) of heavily reinforced concrete buildings, most of which were specially designed to withstand earthquake shock, which were not collapsed by the blast; most of these buildings had their interiors completely gutted, and all windows, doors, sashes, and frames ripped out...While this saved the building frame, it permitted severe damage to building interior and contents, and injuries to the building occupants. Buildings without large panel openings through which the pressure could dissipate were completely crushed, even when their frames were as strong as those which survived...most of the reinforced concrete structures could be classified only as fair, with concrete of low strength and density, with many of the columns, beams, and slabs underdesigned and improperly reinforced. These facts account for some of the structural failures which occurred [sic]}}{{cite web|url=https://archive.org/details/TheEffectsOfTheAtomicBombOnHiroshima|title=The effects of the atomic bomb on Hiroshima, Japan (the secret U.S. Strategic Bombing Survey report 92, Pacific Theatre)|last=Nigel B. Cook|date=11 July 2013|via=Internet Archive}}]]

To highlight the effect that being indoors, and especially below ground can make, despite the lethal open air radiation, blast and thermal zone extending well past her position at Hiroshima, Akiko Takakura survived the effects of the 16 kt atomic bomb at a distance of 300 meters from ground zero, sustaining only minor injuries, due in greatest part to her position in the lobby of the Bank of Japan, a reinforced concrete building, at the time of the nuclear explosion,{{cite web |url=http://www.pcf.city.hiroshima.jp/virtual/VirtualMuseum_e/visit_e/testimony_e/testimo07.html |title=Hiroshima Witness interview |publisher=Pcf.city.hiroshima.jp |access-date=2013-03-11 |archive-date=2012-03-09 |archive-url=https://web.archive.org/web/20120309214634/http://www.pcf.city.hiroshima.jp/virtual/VirtualMuseum_e/visit_e/testimony_e/testimo07.html |url-status=dead }}{{cite web|url=http://www.atomicarchive.com/Docs/Hibakusha/Akiko.shtml |title=Testimony of Akiko Takakura | The Voice of Hibakusha | The Bombing of Hiroshima and Nagasaki | Historical Documents |publisher=atomicarchive.com |access-date=2013-03-11}} and to highlight the protection conferred to an individual who is below ground during a nuclear air burst, Eizo Nomura survived the same blast at Hiroshima at a distance of 170 meters from ground zero.{{cite web |url=http://www.pcf.city.hiroshima.jp/virtual/VirtualMuseum_e/exhibit_e/exh0203_e/exh02033_e.html |title=Special Exhibit 3 |publisher=Pcf.city.hiroshima.jp |access-date=2013-03-11 |archive-date=2018-04-19 |archive-url=https://web.archive.org/web/20180419075520/http://www.pcf.city.hiroshima.jp/virtual/VirtualMuseum_e/exhibit_e/exh0203_e/exh02033_e.html |url-status=dead }} Nomura, who was in the basement of what is now known as the rest house, also a reinforced concrete building, lived into his early 80s.{{cite web|url=http://www5d.biglobe.ne.jp/~LLLtrs/PhotoGlryMain/pgc/Hiroshima01a.html |title="Hiroshima – 1945 & 2007" by Lyle (Hiroshi) Saxon, Images Through Glass, Tokyo |publisher=D.biglobe.ne.jp |date=1945-08-06 |access-date=2013-03-11}}{{cite web|url=http://www.japanfocus.org/-elin_o_Hara-slavick/3196 |title=Hiroshima: A Visual Record |publisher=JapanFocus |access-date=2013-03-11}}{{cite web |url=http://www.kombe-jarvis.com/japan.html |title=Japan |publisher=Kombe-jarvis.com |access-date=2013-03-11 |archive-url=https://web.archive.org/web/20131013191113/http://www.kombe-jarvis.com/japan.html |archive-date=2013-10-13 }}

In contrast to these cases of survival, the unknown person sitting outside on the steps of the Sumitomo Bank next door to the Bank of Hiroshima on the morning of the bombing—and therefore fully exposed—suffered what would have eventually been lethal third- to fourth-degree burns from the near instant nuclear weapon flash if they had not been killed by the slower moving blast wave when it reached them approximately one second later.{{cite web |url=http://www.pcf.city.hiroshima.jp/virtual/museum/index.php?l=e&no=1000 |title=Look at the Exhibits/Damage by the Heat Rays |publisher=Pcf.city.hiroshima.jp |access-date=2013-03-11 |archive-date=2018-01-23 |archive-url=https://web.archive.org/web/20180123085641/http://www.pcf.city.hiroshima.jp/virtual/museum/index.php?l=e&no=1000 |url-status=dead }}

To elucidate the effects on lying flat on the ground in attenuating a weapons blast, Miyoko Matsubara, one of the Hiroshima maidens, when recounting the bombing in an interview in 1999, said that she was outdoors and less than 1 mile from the hypocenter of the Little Boy bomb. Upon observing the nuclear weapons silent flash she quickly lay flat on the ground, while those who were standing directly next to her, and her other fellow students, had simply disappeared from her sight when the blast wave arrived and blew them away.{{cite web |url = http://www.hiroshima-spirit.jp/en/voice/miyoko_e.html|title = Continue to Relate Stupidity of War and Dignity of Life|website = The Spirit of Hiroshima|access-date =2013-03-11|last = Matsubara|first = Miyoko}}{{cite web|url=http://www.wagingpeace.org/articles/1999/00/00_matsubara_spirit-hiroshima.php |title=The Spirit of Hiroshima |publisher=Nuclear Age Peace Foundation |access-date=2013-03-11 |last=Matsubara |first=Miyoko |year=1999 |quote="I quickly lay flat on the ground. Just at that moment, I heard an indescribable deafening roar. My first thought was that the plane had aimed at me"..."I had no idea how long I had lain unconscious, but when I regained consciousness the bright sunny morning had turned into night. Takiko, who had stood next to me, had simply disappeared from my sight. I could see none of my friends nor any other students. Perhaps they had been blown away by the blast." |archive-url=https://web.archive.org/web/20130420074231/http://www.wagingpeace.org/articles/1999/00/00_matsubara_spirit-hiroshima.php |archive-date=April 20, 2013 }}

Position of the body can have a considerable influence in protection from blast effects. Lying prone on the ground will often materially lessen direct blast effects because of the protective defilade effects of irregularities in the ground surface. Ground also tends to deflect some of the blast forces upward. Standing close to a wall, even on the side from which the blast is coming, also lessens some of the effect. Orientation of the body also affects severity of the effect of blast. Anterior exposure of the body may result in lung injury, lateral position may result in more damage to one ear than the other, while minimal effects are to be anticipated with the posterior surface of the body (feet) toward the source of the blast.{{cite book |chapter-url = http://history.amedd.army.mil/booksdocs/wwii/woundblstcs/chapter2.htm|title = Wound Ballistics in World War II – Supplemented by Experiences in the Korean War|chapter = II: Ballistic Characteristics of Wounding Agents|editor-last = Coates|editor-first = James Boyd Jr.|editor-last2 = Beyer|editor-first2 = James C.|publisher = The Historical Unit, United States Army Medical Service|lccn = 62-60002|year = 1984|location = Washington, D.C.}}

The human body is more resistant to sheer overpressure than most buildings, however, the powerful winds produced by this overpressure, as in a hurricane, are capable of throwing human bodies into objects or throwing debris at high velocity, both with lethal results, rendering casualties highly dependent on surroundings.{{cite web|url=https://www.cdc.gov/niosh/docket/archive/pdfs/NIOSH-125/125-ExplosionsandRefugeChambers.pdf |title=1) Effects of blast pressure on the human body |access-date=2012-10-12}} For example, Sumiteru Taniguchi recounts that, while clinging to the tremoring road surface after the Fat Man detonation, he witnessed another child being blown away, the destruction of buildings around him and stones flying through the air.{{cite web |url= https://www.pbs.org/wgbh/peoplescentury/episodes/fallout/taniguchitranscript.html |title= Interview with Sumiteru Taniguchi Japanese Citizen, Nagasaki |access-date=2007-08-13 |date= 1999-06-15 |website= People's Century: Fallout |publisher= PBS}} Similarly, Akihiro Takahashi and his classmates were blown by the blast of Little Boy by a distance of about 10 meters, having survived due to not colliding with any walls etc. during his flight through the air.{{cite web |url=http://history.hanover.edu/courses/excerpts/111hiroshima.html |title=Hiroshima Survivors' Testimony, Reformatted from the Original Electronic Text at Voice of Hibakusha}} Likewise, Katsuichi Hosoya had a near identical testimony.{{cite web |url=http://www.asahi.com/hibakusha/english/shimen/happened/happened-01.html |title='What Happened On This Date' It's hot! Help! Water please! - Hiroshima 8/6 Recreated (August 6, 2005, The Asahi Shimbun Newspaper Morning Edition) Katsuichi Hosoya has a similar account of being "blown several meters"}}

During the 2013 Chelyabinsk meteor explosion, a fourth-grade teacher in Chelyabinsk, Yulia Karbysheva, saved 44 children from potentially life-threatening ballistic window glass cuts by ordering them to hide under their desks when she saw the flash. Despite not knowing the origin of the intense flash of light, she ordered her students to execute a duck and cover drill. Ms. Karbysheva, who herself did not duck and cover but remained standing, was seriously lacerated when the explosion's blast wave arrived, and window glass blew in, severing a tendon in one of her arms; however, not one of her students, who she ordered to hide under their desks, suffered a cut.{{cite news|url=https://www.nytimes.com/2013/02/17/world/europe/russians-seek-clues-and-count-blessings-after-meteor-blast.html?_r=1& |title=After Assault From the Heavens, Russians Search for Clues and Count Blessings |newspaper=The New York Times |date=16 February 2013 |access-date=2013-11-30|last1=Kramer |first1=Andrew E. }} A follow-up study of the effects of the meteor airburst determined that the windows most prone to breaking when exposed to a blast overpressure are those of school buildings, which tend to be large in area.{{cite web|url=http://cams.seti.org/index-chelyabinsk.html|title=Cameras for Allsky Meteor Surveillance (CAMS)}}

While the bombings of Hiroshima and Nagasaki demonstrated that the urban area of glass breakage is nearly 16 times greater than the area of significant structural/building damage, although improved building codes since then may contribute to better building survival, there would be a higher likelihood of glass breakage and therefore potential injury/death for people near windows because many modern buildings have larger windows.{{cite web |url=http://www.nae.edu/Publications/Bridge/19804/19920.aspx |title= Reducing the Consequences of a Nuclear Detonation: Recent Research Author: Brooke Buddemeier, 2010 NAE}}

{{main| Duck and Cover (film)}}

{{See also|heat transfer rate|Thermal dose unit|Emissivity|blackbody radiation|coulomb repulsion|Odeillo solar furnace|Arc flash#Distance|Anti-flash white}}

File:AtomicEffects-p26b.jpg |archive-url=https://web.archive.org/web/20130302091606/http://www.acq.osd.mil/ncbdp/nm/nm_book_5_11/appendix_F.htm |archive-date=2013-03-02 }}{{cite web |url=https://www.youtube.com/watch?v=NjHriyuzDz4 |title=Big Picture: Individual Protection Against Atomic Attack - National Archives and Records Administration - ARC Identifier 2569661 / Local Identifier 111-TV-393 - DVD Copied by Katie Filbert - Department of Defense. Circa 6:40 minutes in|website=YouTube|date=13 November 2010 }} In this case a valve protected a portion of the bitumen{{cite web |url=https://archive.org/details/BritishMissionToJapan|title=British Mission to Japan|last=Nigel B. Cook |via=Internet Archive}} coated wall of a gas holder from having a line-of-sight with the nuclear fireball whereas all unshadowed surfaces were lightened, akin to a near instant "sun fading" of the coating.Original caption: "Shadow" of band valve wheel on paint of a gas holder at Hiroshima. Radiant heat instantly burned paint where the heat rays were not obstructed. 6,300 feet from ground zero (Japanese photo). United States Strategic Bombing Survey, The Effects of Atomic Bombs on Hiroshima and Nagasaki (United States Government Printing Office: Washington, 1946) Chapter 3. A large number of these permanent markings were used, by extrapolating backward, to determine the exact point of detonation in the sky.{{cite book |chapter-url=http://www.rerf.or.jp/shared/ds02/pdf/chapter01/cha01-p42-61.pdf |chapter=Bomb Parameters |last1=Kerr |first1=George D. |last2=Young |first2=Robert W. |last3=Cullings |first3=Harry M. |last4=Christy |first4=Robert F. |pages=42–43 |title=Reassessment of the Atomic Bomb Radiation Dosimetry for Hiroshima and Nagasaki – Dosimetry System 2002 |year=2005 |publisher=The Radiation Effects Research Foundation |editor=Robert W. Young, George D. Kerr}}{{cite web |url=http://www.osti.gov/manhattan-project-history/publications/LANLHiroshimaNagasakiYields.pdf |title=The Yields of the Hiroshima and Nagasaki Explosions |last=Malik |first=John |date=September 1985 |publisher=Los Alamos National Laboratory |access-date=March 9, 2014}}Malik (1985) describes how various values were recorded for the B-29's altitude at the moment of bomb release over Hiroshima. The strike report said 30,200 ft, the official history said 31,600 ft, Commander Parson's log entry was 32,700 ft, and the navigator's log was 31,060 ft—the latter possibly an error transposing two digits. A later calculation using the indicated atmospheric pressure arrived at the figure of 32,200 ft.
Similarly, several values have been reported as the altitude of the Little Boy bomb at the moment of detonation. Published sources vary in the range of {{convert|1800|to|2000|ft|m|abbr=on}} above the city. The device was set to explode at {{convert|1885|ft|m|abbr=on}}, but this was approximate. Malik (1985) uses the figure of {{convert|1903|ft|m|abbr=on}} plus or minus 50 ft (15 m), determined after data review by Hubbell et al. (1969). Radar returns from the tops of multistory buildings near the hypocenter may have triggered the detonation at a somewhat higher altitude than planned. Kerr et al. (2005) found that a detonation altitude of {{convert|600|m|ft|1|abbr=on}}, plus or minus {{convert|20|m|ft|1|abbr=on}}, gave the best fit for all the measurement discrepancies.]]

File:Effects of atomic heat and radiation on humans. Japan - NARA - 292632.jpg bomb; this photo displays 1st- and 2nd-degree burn injuries he experienced on his unclothed skin, the shoulder and arm, while the thin vest garment of clothing, a radiant barrier, that he was wearing at the time of the explosion completely protected his stomach and lower chest from experiencing similar burns. A clearer color restored version of this picture is also available.{{cite web|url=http://www.remm.nlm.gov/PlanningGuidanceNuclearDetonation.pdf |title=Planning Guidance for Response to a Nuclear Detonation (figure 1.5) |publisher=Remm.nlm.gov |access-date=2013-11-30}}r]]

The advice to cover one's exposed skin with anything that can cast a shadow, like the picnic blanket and newspaper used by the family in the film, may seem absurd at first when one considers the capabilities of a nuclear weapon. However, even the thinnest of barriers such as clothAtomic Weapons Orientation Part Five film circa 8mins{{usurped|1=[https://web.archive.org/web/20180824013014/http://www.dtic.mil/dtic/tr/fulltext/u2/024860.pdf spectral reflectance of common indoor fuels.]}}{{cite web|url=http://www.dtic.mil/dtic/tr/fulltext/u2/267637.pdf|archive-url=https://web.archive.org/web/20180824020605/http://www.dtic.mil/dtic/tr/fulltext/u2/267637.pdf|archive-date=24 August 2018|title=Technical report |date=24 August 2018}} or plant leaves would reduce the severity of burns on the skin from the thermal radiation with the flash light, similar in average emission spectrum/color to sunlight.http://dge.stanford.edu/SCOPE/SCOPE_28_1/SCOPE_28-1_1.1_Chapter1_1-23.pdf SCOPE report, page 6{{cite web|url=https://ke.army.mil/bordeninstitute/published_volumes/nuclearwarfare/chapter1/chapter1.pdf|archive-url=https://web.archive.org/web/20170125171152/https://ke.army.mil/bordeninstitute/published_volumes/nuclearwarfare/chapter1/chapter1.pdf|archive-date=25 January 2017|title=Nuclear warfare |date=25 January 2017}}{{cite journal |doi=10.1016/0038-092X(65)90052-6 |title=Feasibility study of pulse shaping for a solar furnace |journal=Solar Energy |volume=9 |issue=4 |pages=217–222 |year=1965 |last1=Drew |first1=G.G. |bibcode=1965SoEn....9..217D }} The thermal radiation emits in the ultraviolet, visible light, and infrared range but with a higher light intensity than sunlight, and this combination of light rays is capable of delivering radiant burning energy to exposed skin areas.{{cite web|url=http://www.fourmilab.ch/etexts/www/effects/eonw_7.pdf |title=Thermal Radiation and Its Effects: Chapter VII |publisher=Fourmilab.ch |access-date=2013-11-30}}[https://archive.org/details/JTF3PresentsOperationGREENHOUSE1951 Joint Task Force 3 Presents Operation GREENHOUSE. c. 56 minutes. Pig skin tested behind shutters and filters]Operation greenhouse. Scientific director`s report of atomic weapon tests at Eniwetok, 1951. Volume 2. Part 2. Evaluation of program As the time-to-rise at peak and total duration of the emittance pulse of this burning thermal radiation is both prolonged and increases with larger explosive yield,Atomic Weapons Orientation Part Six film, circa 23 mins it is usually at least a few seconds long for all high yield stockpiled weapons, creating the potential for protective countermeasures.{{cite book|title=Field Manual No.1-111: Aviation Brigades|url=https://books.google.com/books?id=wbCgLzRyM6YC&pg=RA5-PA4|publisher=DIANE Publishing|isbn=978-1-4289-1102-4|page=5}}

High importance is given to closing eyelids and covering the eyes as temporary or permanent flash blindness is a risk potential without this covering, especially at night.{{cite web |url=https://www.youtube.com/watch?v=NjHriyuzDz4 |title=Big Picture: Individual Protection Against Atomic Attack - National Archives and Records Administration - ARC Identifier 2569661 / Local Identifier 111-TV-393 - DVD Copied by Katie Filbert - Department of Defense|website=YouTube|date=13 November 2010 }}

A photograph taken about 1.3 km from the hypocenter of the Hiroshima bomb explosion showed that the shadowing effect of leaves from a nearby shrub protected a wooden utilities pole from charring discoloration due to the burst of thermal radiation; the rest of the telephone pole, which was not under the protection of the leaves, was charred almost completely black.{{cite web |url=http://www.pcf.city.hiroshima.jp/virtual/VirtualMuseum_e/visit_e/subcon/he113c.html |title=Damage by the Heat Rays/Shadow Imprinted on an Electric Pole |publisher=Pcf.city.hiroshima.jp |access-date=2013-11-30 |archive-date=2019-09-12 |archive-url=https://web.archive.org/web/20190912204915/http://www.pcf.city.hiroshima.jp/virtual/VirtualMuseum_e/visit_e/subcon/he113c.html |url-status=dead }} The difference in required flash-energy necessary to produce essentially immediate, though transitory, non-propagating flaming, and that required to achieve a continued self-sustained propagating flaming are orders of magnitude in difference for most combustible materials. In the case of untreated timber it is largely dependent on the depth of char.{{usurped|1=[https://web.archive.org/web/20180728212952/http://www.dtic.mil/dtic/tr/fulltext/u2/009336.pdf project 5046 pg 12]}}Evaluation of Thermal Effects on Specimens Exposed at Bikini (NML Project 5046, Part 7, Confidential) (March, 1950).Investigation of Radiation Effects on Wood Specimens Exposed During the Able Test at Bikini While the propagating fires in both Japanese cities were almost exclusively ignited by the blast wave overturning charcoal cooking-braziers and similar secondary events, thermal flash-fires from untreated fabric and timber in the urban environment is considered potentially the widest destructive effect of the higher yield explosive devices.

The Nevada test site used for testing nuclear devices had a dry desert environment with low humidity, which repeatedly demonstrated the flash-combustion effect during tests. Many investigative films made on location there, such as The House in the Middle and others, focused on the combustion of fabrics and clothing.

In the only human accounts at these high luminous intensities that are not of the more common Arc flash accidents, a number of the Hiroshima Maidens survived despite their close proximity to the explosion and in a range where the flash-fire of their customary Japanese summer attire, made of thin kimono cloth, was near instantaneous. As their clothing combusted, some of the Maidens performed an incomplete stop, drop and roll in an effort to extinguish the flames.{{cite web |url=http://www.cbc.ca/archives/categories/war-conflict/second-world-war/shadows-of-hiroshima/bombing-was-justified-says-survivor.html |title=Hiroshima: Bombing was justified, says survivor}}

{{See also|Neutron emission#Neutron emission in fission|Armed Forces Radiobiology Research Institute|Dosimetry|Orders of magnitude (radiation)|Dose fractionation|Radiation-induced cancer|Treatment of infections after exposure to ionizing radiation}}

While not designed for those faced with low-yield neutron bombs or for those who are, in general, so close to the nuclear fireball that prompt/initial radiation would be life-threatening in the short-medium term, ducking and covering would nevertheless slightly reduce exposure to the initial gamma rays, specifically the portion emitted after the first flash of visible light.{{cite web|url=http://discovery.nationalarchives.gov.uk/SearchUI/Details/AssetMain?iaid=C1271982 |title=The advantage of lying prone in reducing the dose of gamma rays from an airburst atomic... | The National Archives |publisher=Discovery.nationalarchives.gov.uk |access-date=2013-11-30}} The initial gamma rays are defined as those emitted from the fireball & following mushroom cloud which can reach personnel on the ground for a total of approximately 1 minute, at which point the intensity of the radiation has diminished and the atmosphere itself is thick enough to act as full shielding.{{cite web|url=http://www.acq.osd.mil/ncbdp/nm/nm_book_5_11/appendix_F.htm |title=The Nuclear Matters Handbook |quote=For surface and low-air bursts, the fireball will rise quickly, and within approximately one minute, it will be at an altitude high enough similar that none of the gamma radiation produced inside the fireball will have any impact to people or equipment on the ground. For this reason, initial nuclear radiation is defined as the nuclear radiation produced within one minute post-detonation. Initial nuclear radiation is also called prompt nuclear radiation. |archive-url=https://web.archive.org/web/20130302091606/http://www.acq.osd.mil/ncbdp/nm/nm_book_5_11/appendix_F.htm |archive-date=2013-03-02 }}{{cite book|chapter-url = http://ke.army.mil/bordeninstitute/published_volumes/nuclearwarfare/chapter1/chapter1.pdf |url-status = live| archive-url = https://web.archive.org/web/20161229163720/https://ke.army.mil/bordeninstitute/published_volumes/nuclearwarfare/chapter1/chapter1.pdf|archive-date = 29 December 2016|publisher = Borden Institute|chapter = Chapter 1 - Nuclear Events and Their Consequences|title = Medical Consequences of Nuclear Warfare|last1= Alt|first1 = Leonard A.|last2= Forcino|first2= C. Douglas |last3 = Walker|first3 = Richard I.}}{{cite web |url=https://fas.org/nuke/guide/usa/doctrine/dod/fm8-9/1ch3.htm |title=Chapter 3 Effects of nuclear explosions section I – General}}{{cite web|url=http://www.oektg.at/wp-content/uploads/02-Nuclear-Engineering-Overview1.pdf|archive-url=https://web.archive.org/web/20180515201022/http://www.oektg.at/wp-content/uploads/02-Nuclear-Engineering-Overview1.pdf|archive-date=15 May 2018|title=Nuclear engineering overview |date=15 May 2018}}

As approximately half of these gamma rays are emitted in the first second and the other half, over the following 59[Desert Rock VI Exercise: "The Atom Soldier" 1955 US Army; The Big Picture TV-308 circa 15 mins 30 secs] alongside gamma rays being mostly emitted in a straight line, people lying on the ground will more likely have obstacles serving as radiation protection such as building walls, foundations, car engines, etc. between their bodies and the radiation emitted from both the fireball and the accompanying lower levels of radiation that continue to arrive at the ground for about 1 minute, during the mushroom cloud phase, which is termed "cloudshine".{{cite web|url=http://www.remm.nlm.gov/nuclearexplosion.htm|title=Nuclear Detonation: Weapons, Improvised Nuclear Devices - Radiation Emergency Medical Management}} It would also give protection from the even smaller fraction of radiation that changes direction and is randomly reflected and scattered by the air/"skyshine".{{cite web|url=https://books.google.com/books?id=opAklHndAy8C&q=%22fukuryu+maru%22+ash&pg=PA6|title=Structure shielding against fallout gamma rays from nuclear detonations|first1=Lewis Van Clief|last1=Spencer|first2=Arthur B.|last2=Chilton|first3=Charles|last3=Eisenhauer|first4=Center for Radiation|last4=Research|first5=United States National Bureau of|last5=Standards|first6=University of Illinois at|last6=Urbana-Champaign|date=1 January 1980|publisher=U.S. Dept. of Commerce, National Bureau of Standards|via=Google Books}} Approximately "One and one half inches"/37 mm of steel will reduce gamma dose by half.{{cite web |url=https://www.youtube.com/watch?v=NjHriyuzDz4 |title=Big Picture: Individual Protection Against Atomic Attack - National Archives and Records Administration - ARC Identifier 2569661 / Local Identifier 111-TV-393 - DVD Copied by Katie Filbert - Department of Defense. Circa 10:20 minutes in|website=YouTube|date=13 November 2010 }} Its half-value thickness.

The effective gamma ray energy of the cloudshine is not especially high, 200 KeV.{{Cite report |title=Operation Greenhouse. Scientific Director's report of atomic weapon tests at Eniwetok, 1951. Annex 6. 8. cloud radiation field|date=1 April 1985|publisher=US government|osti = 7248965}}

Unlike the relatively low-yield, or low explosive energy "A-bombs" dropped on Hiroshima and Nagasaki, which did result in a sizable proportion of injuries from prompt radiation, higher yield "hydrogen bombs" (thermonuclear weapons) are not expected to result in very many such injuries – as the range at which the ionizing radiation from higher yield devices is of primary concern, is already well inside the hyper-lethal blast and flash burn areas.Atomic Weapons Orientation Part Six film, circa 17 mins

{{See also|Neptunium-239|Iodine-131|Black Rain (novel) |Potassium iodide |Human decontamination |Project 4.1 |Nuclear War Survival Skills |Textbook of Military Medicine}}

Apart from the intrinsic "prompt effects" of nuclear detonations, that of thermal flash, blast and initial radiation releases, if any part of the fireball of the nuclear detonation contacts the ground, in what is known as a surface burst, another, comparatively slowly increasing, radiation hazard will also begin to form in the immediate area.{{cite book |url=https://books.google.com/books?id=CAUYAAAAYAAJ&q=%22beta+burns%22&pg=PA18 |title=Nuclear handbook for medical service personnel |author=United States. Dept. of the Army|page=18|year=1990}}{{cite book |url=https://books.google.com/books?id=Y-k5h07NkFcC&q=%22beta+burns%22&pg=PA77 |title=Medical management of radiation accidents|author1=Igor A. Gusev |author2=Angelina Konstantinovna Guskova |author3=Fred Albert Mettler |page=77|publisher=CRC Press|year=2001|isbn=978-0-8493-7004-5}}

Putting aside the possibility of the detonation occurring during an already established heavy rain-storm, the formation of this life-threatening "delayed nuclear radiation" manifests only when the altitude, or "height of burst" of the explosion, is such that both the fireball and the buoyant updrafts it creates, sufficiently heats and lifts the soil that was below it into the core of the mushroom cloud. Once there, the very hot radioactive isotope products of the nuclear reactions that produced the explosion, begin to coalesce with the cooler and denser soil. Upon cooling, this mixture begins to locally fall-out or precipitate-out of the mushroom cloud, falling back to the surface of the earth, near to the point of detonation, over the next few minutes and hours.{{cite web |url=https://www.theatlantic.com/national/archive/2011/01/the-unexpected-return-of-duck-and-cover/68776/|title=The Unexpected Return of 'Duck and Cover'|first=Glenn Harlan |last=Reynolds |website=The Atlantic|date = 4 January 2011}}

While the duck and cover countermeasure, in its most basic form, offers a small to negligible protection against fallout, the technique assumes that after the effects of the blast and initial radiation subside, with the latter of which being no longer a threat after about "twenty seconds" to 1 minute post detonation, a person who ducks and covers will realize when it is wise to cease ducking and covering (after the blast and initial radiation danger has passed) and to then seek out a more sheltered area, like an established or improvised fallout shelter to protect themselves from the ensuing potential local fallout danger, as depicted in the film.

After all, "Duck and Cover" is a first response countermeasure only, in much the same way that "Drop, Cover and Hold On" is during an earthquake, with the advice having served its purpose once the earthquake has passed, and possibly other dangers—like a tsunami or fallout—may be looming, which then require movement to high ground and radiation protection, respectively.

However, if such a shelter is unavailable, the person should then be advised to follow the Shelter in Place protocol, or if given, emergency evacuation advice. Evacuation orders would entail exiting the area completely by following a path perpendicular to the wind direction and therefore perpendicular to the path of the fallout plume.{{cite web|url=https://www.dhs.gov/xlibrary/assets/prep_nuclear_fact_sheet.pdf |title=Nuclear Attack |publisher=U.S. Department of Homeland Security |date = 2005}} Taking upper atmospheric winds into account, surface winds alone are not to be depended upon as indicative of the direction of fallout movement.[https://archive.org/details/Radiolog1961 Radiological defense 1961 c 12 minutes] "Sheltering in place" is staying indoors, in a preferably sealed tight basement, or internal room, for a number of hours, with the oxygen supply available in such a scenario being more than sufficient for 3+ hours in even the smallest average room, under the assumption that the improvised seal is perfect, until carbon dioxide levels begin to reach unsafe values and necessitate room unsealing for a number of minutes to create a room air change.{{cite web |url=http://orise.orau.gov/csepp/documents/planning/reports/misc-reports/paperSIP010406.pdf |title=Journal of Hazardous Materials A119 (2005) 31–40 Effectiveness of expedient sheltering in place in a residence, James J. Jetter, Calvin Whitfield |archive-url=https://web.archive.org/web/20131111103357/http://orise.orau.gov/csepp/documents/planning/reports/misc-reports/paperSIP010406.pdf |archive-date=2013-11-11 }}{{cite journal |title=A systems approach to the design of safe-rooms for shelter-in-place | doi=10.1007/S12273-009-9301-2 | volume=2 |journal=Building Simulation |pages=41–51|year = 2009|last1 = Bennett|first1 = James S| s2cid=109770220 }} {{subscription required}}

In the era the advice was originally given, the most common nuclear weapons were weapons comparable to the US Fat Man and Soviet Joe-1 in yield. The most far-reaching dangers that initially come from the nuclear explosion of this, and higher, yield weapons as airbursts, are the initial flash/heat and blast effects and not from fallout. This is due to the fact that when nuclear weapons are detonated to maximize the range of building destruction, that is, maximize the range of surface blast damage, an airburst is the preferred nuclear fuzing height,{{cite book|title = Critical Assembly: A Technical History of Los Alamos During the Oppenheimer Years, 1943-1945|last1=Hoddeson |first1=Lillian|author-link=Lillian Hoddeson|first2=Paul W. |last2=Henriksen |first3=Roger A. |last3=Meade |first4=Catherine L. |last4=Westfall|author4-link= Catherine Westfall|date = 1993|pages=183–184|url = https://books.google.com/books?id=kBBu7lTJc4EC|isbn = 9780521441322|publisher = Cambridge University Press}} as it exploits the mach stem phenomenon. This phenomenon of a blast wave occurs when the blast reaches the ground and is reflected. Below a certain reflection angle the reflected wave and the incident wave merge and form a reinforced horizontal wave; this is known as the 'Mach stem' (named after Ernst Mach) and is a form of constructive interference and consequently extends the range of high pressure.{{cite web|url=http://www.atomicarchive.com/Effects/effects6.shtml |title=The Mach Stem | Effects of Nuclear Weapons |publisher=atomicarchive.com |access-date=2014-04-26}}{{cite web|url=https://www.fas.org/nuke/intro/nuke/blast.htm |title=Nuclear Weapon Blast Effects |publisher=Fas.org |access-date=2014-04-26}}[http://www.atomicarchive.com/Movies/machstem.shtml] video of the mach 'Y' stem, note that it is not a phenomenon unique to nuclear explosions, conventional explosions also produce it.{{cite web |url=http://apps.dtic.mil/dtic/tr/fulltext/u2/a159214.pdf |archive-url=https://web.archive.org/web/20140311035652/http://www.dtic.mil/dtic/tr/fulltext/u2/a159214.pdf |url-status=live |archive-date=March 11, 2014 |title=Mach stem modeling with spherical shock waves, AFIT/GNE/ENP/85M-6 by William E. Eichinger, 1985}} Air-burst fuzing also increases the range that people's skin will have a line-of-sight with the nuclear fireball. However, as a result of the high altitude of the explosion, most of the radioactive bomb debris is dispersed into the stratosphere, with a great column of air therefore placed between the vast majority of the bomb debris/fission reaction products and people on the ground for a number of crucial days before it falls out of the atmosphere in a comparatively dilute fashion. This "delayed fallout" is henceforth not an immediate concern to those near the blast. On the other hand, the only time that fallout is rapidly concentrated in a potentially lethal fashion in the local/regional area around the explosion is when the nuclear fireball makes contact with the ground surface, with an explosion that does so, being aptly termed a surface burst.{{cite web|url=http://www.fourmilab.ch/etexts/www/effects/ |title=The Effects of Nuclear Weapons |publisher=Fourmilab.ch |access-date=2013-11-30}} For example, in the Operation Crossroads tests of 1946 on Bikini Atoll, using two explosive devices of the same design and yield, the first, Test Able (an air burst) had little local fallout, but the infamous Test Baker (a near surface shallow underwater burst) left the local test targets badly contaminated with radioactive fallout.

Widespread radioactive fallout itself was not recognized as a threat among the public at large before 1954, until the widely publicized story of the 15-megaton surface burst of the experimental test shot Castle Bravo on the Marshall Islands. The explosive yield of the Castle Bravo device the Shrimp was unexpectedly high and therefore correspondingly higher amounts of local fallout were produced. When this arrived at their location carried by the wind, this caused the 23 crew members on a Japanese fishing boat known as the Lucky Dragon to come down with acute radiation sickness with varying degrees of seriousness{{cite book|url=https://books.google.com/books?id=sDQrAAAAYAAJ&q=%22beta+burns%22&pg=PA248 |page=248|title=Mass burns: proceedings of a workshop, 13–14 March 1968|author=National Research Council (U.S.). Committee on Fire Research, United States. Office of Civil Defense|publisher=National Academies|year=1969}} and due to complications in the treatment of the ship's radio operator months after the exposure, resulted in his death.

It is, however, unlikely that a well-funded belligerent with nuclear weapons would waste their weapons with fuzing to explode below or on the surface, as both test shot Baker and Castle Bravo were respectively. Instead, to maximize the range of city blast destruction and immediate death, an air burst is preferred, as the ≈500 meter explosion heights of the only nuclear weapons used on cities, Little Boy and Fat Man also attest to.Nichols, K. D. "The Road to Trinity" pages 175, 198, 223 (1987, Morrow, New York) {{ISBN|0-688-06910-X}} Moreover, with air bursts the total amount of radiation contained in the fallout, in units of activity/becquerel, is somewhat less than the total that would be released from a surface or subsurface burst, as in comparison, depending on the height of burst, little to no neutron activation or neutron induced gamma activity of soil occurs from air bursts.{{cite book|title = Disaster Medicine |edition = 2nd |year = 2007 |editor-first = David E. |editor-last = Hogan|chapter-url = https://books.google.com/books?id=hgLccSb8DIUC|page = 384 |chapter = Nuclear Detonations: Evaluation and Response|last = Fong|first = Fun H. Jr.|publisher = Lippincott Williams & Wilkins |isbn = 9780781762625 }}

Therefore, the initial danger from concentrated local/'early' fallout (which takes on the color of the soil around the fireball, commonly with a dusty pumice or ash-like appearance, as experienced by the crew of the Lucky Dragon) remains low in a global nuclear war scenario. Instead the fallout most likely to be encountered by most survivors in this scenario is expected to be the less dangerous but widely spread global/'late' fallout.{{cite web|url=http://www.fourmilab.ch/etexts/www/effects/ |title=The Effects of Nuclear Weapons, chapter IX |publisher=Fourmilab.ch |access-date=2013-03-11}} An air burst at optimum height will produce a negligible amount of early fallout.Fong (2007), pp. 384 & 385

A notable comparison to underline this is found when one compares the 50 megaton air-burst Tsar Bomba, which produced no concentrated local/early fallout and thus no known deaths from radiation, with the surface burst of the 15 megaton Castle Bravo, which in comparison, due to the local fallout produced, was implicated in the death of 1 of 23 crew on the Lucky Dragon and made the entire Bikini Atoll unfit for further nuclear testing until enough time elapsed and the intensity of the radiation field had decayed to acceptable levels.{{efn |1=By 1958, a total of 23 nuclear devices were exploded on or near the atoll,{{cite web|url=http://www.bikiniatoll.com/BIKINICORALS.pdf |title=Bikini Atoll coral biodiversity resilience five decades after nuclear testing |access-date=2013-08-13 |archive-url=https://web.archive.org/web/20131029195238/http://www.bikiniatoll.com/BIKINICORALS.pdf |archive-date=2013-10-29 }} with the majority occurring after the 1954 Operation Castle series, resulting in a total of about 42 megatons of pure fission product fallout being generated around the atoll. This made permanent above ground habitation without remediation unwise for a decade or so; it was thus resettled in 1968. The inhabitants lived there again from 1968 to 1978, abandoning the atoll in 1978. As of 2014, the atoll has had infrequent inhabitants since the 1990s, mainly for tours – a return to permanent safe habitation would require locally produced and consumed plant food to be grown with fertilizer, or alternatively, only imported plant food to be eaten.[http://www-ns.iaea.org/appraisals/bikini-atoll.asp] [http://www.outsideonline.com/outdoor-adventure/nature/Paradise-With-An-Asterisk.html]}}

File:OperationDoorstep1-BasementMother.jpg mother and daughter mannequin pair in an improvised basement lean-to shelter prior to testing in Upshot-Knothole Annie. To shelter-in-place in such an area would offer, in a number of outdoor dose rates, an adequate fallout radiation protection factor (PF) or "dose reduction factor" of 20 or more. More effective basement spaces did/do exist however, of "10 million" homes assessed in 1968, 500,000 US basements were found to have a PF-40.{{cite web |url=http://www.training.fema.gov/EMIWeb/edu/docs/HistoricalInterest/Office%20of%20Civil%20Defense%20-%201968%20-%20Annual%20Report.pdf |title=Annual report of the office of civil defense 1968. National Fallout Shelter Survey pg 29,37-38 |access-date=2014-08-26 |archive-url=https://web.archive.org/web/20130221213408/http://training.fema.gov/emiweb/edu/docs/HistoricalInterest/Office%20of%20Civil%20Defense%20-%201968%20-%20Annual%20Report.pdf |archive-date=2013-02-21 }}]]

Furthermore, regardless of if a nuclear attack on a city is of the surface or air-burst variety or a mixture of both, the advice to shelter in place, in the interior of well-built homes, or if available, fallout shelters, as suggested in the film Duck and Cover, will drastically reduce one's chance of absorbing a hazardous dose of radiation.{{cite web |url=https://travel.state.gov/travel/tips/health/health_1184.html |title=Radiological and Nuclear Incidents |publisher=Travel.state.gov |access-date=2013-03-11 |archive-url=https://web.archive.org/web/20130316000711/http://travel.state.gov/travel/tips/health/health_1184.html |archive-date=2013-03-16 }} A real-world example of this occurred after the Castle Bravo test where, in contrast to the crew of the Lucky Dragon, the firing crew that triggered the explosion safely sheltered in their firing station until after a number of hours had passed and the radiation levels outside fell to dose rate levels safe enough for an evacuation to be considered.{{cite web|url=http://www.sonicbomb.com/content/atomic/docs/trapped_by_radioactive_fallout.pdf|author= Dr. John C. Clark as told to Robert Cahn|title= Trapped by Radioactive Fallout, Saturday Evening Post|date= July 1957}} accessed Feb 20, 2013{{cite web |url=http://www.dgely.com/Bikini/Nuclear%20Testing/Operation%20Castle/Operation%20Castle%20Bravo%20Blast.htm |title=Operation Castle Bravo Blast |publisher=Dgely.com |access-date=2013-11-30 |archive-date=2013-10-22 |archive-url=https://web.archive.org/web/20131022173734/http://www.dgely.com/Bikini/Nuclear%20Testing/Operation%20Castle/Operation%20Castle%20Bravo%20Blast.htm |url-status=usurped }} The comparative safety experienced by the Castle Bravo firing crew served as a proof of concept to civil defense personnel that shelter in place (or "buttoning up" as it was known then) is an effective strategy in mitigating the potentially serious health effects of local fallout.

The minimum typical protection factor of the fallout shelters in US cities is 40 or more. In many cases these shelters are nothing more than the interior of pre-existing well-built buildings that have been inspected, and following their protection factors being calculated, re-purposed as fallout shelters.{{cite web|url=https://archive.org/details/radioactive_fallout_and_shelter |title=Radioactive Fallout and Shelter : US Office of Civil Defense : Free Download & Streaming: Internet Archive |year=1965 |access-date=2013-11-30}}{{cite web |url=http://home.howstuffworks.com/home-improvement/household-safety/tips/fallout-shelter2.htm |title=How Fallout Shelters Work|publisher = HowStuffWorks.com|last = Fuller|first = John|date = 7 April 2008}}{{cite journal|title=Architects of Armageddon: the Home Office Scientific Advisers' Branch and civil defence in Britain, 1945–68 |journal=The British Journal for the History of Science |volume=43 |issue=2 |pages=149–180 |publisher=Journals.cambridge.org |doi=10.1017/S0007087409990392 |year=2010 |last1=Smith |first1=Melissa |s2cid=145729137 }}

A protection factor of at least 40 means that the radiation shielding provided by the shelter reduces the radiation dose experienced by at least 40 times that which would be experienced outside the shelter with no shielding. "Protection factor" is equivalent to the modern term "dose reduction factor".

File:Fallout G&D77.JPG, this is a simplistic model (Gaussian) of a wind-blown fallout map, which depicts the unshielded ground level fallout gamma ray dose and dose rate contours expected to follow a 2 megaton land surface burst detonation, with 1 megaton of the yield coming from fission reactions. Because of radioactive decay, the dose rate contours (on the right) contract after fallout has arrived, but the total absorbed dose contours (left) continue to grow. A similar color version of the right panel, dose rate contour plot, for a 0.1 to 10 kiloton surface burst is also available.{{cite web|url=http://www.remm.nlm.gov/PlanningGuidanceNuclearDetonation.pdf |title=Planning Guidance for Response to a Nuclear Detonation (figure 1.8) |publisher=Remm.nlm.gov |access-date=2013-11-30}} Acutely dangerous regions of fallout are accompanied by fallout particles which are large enough to be detected by eye during its falling out/deposition, that is, they are equal to or larger than the size of dust. All of the ARS deaths following the Chernobyl accident were due to external beta burns. The beta particle to gamma energy ratio is usually greater than 3 in the timeframe of fallout with the greatest threat to life. Protection from physical contact with the dust therefore greatly reduces radiation exposure.{{cite web |author=Fred A. Mettler |url=http://www.nationalacademies.org/hmd/~/media/Files/Activity%20Files/PublicHealth/NucEventPrepWS/METTLERIOMNuclearWorkshop1.pdf |title=Medical decision making and care of casualties from delayed effects of a nuclear detonation |access-date=2018-04-10 |archive-url=https://web.archive.org/web/20180712190941/http://www.nationalacademies.org/hmd/~/media/Files/Activity%20Files/PublicHealth/NucEventPrepWS/METTLERIOMNuclearWorkshop1.pdf |archive-date=2018-07-12 }} The beta decaying uranium-237 and neptunium-239, that are generated from the neutron capture of U-235 and Pu-239 respectively, are regarded as the leading hazardous radioisotopes in the first hour-to-week period following nuclear fallout, with Np-239 dominating "the spectrum for several days".{{cite book |title=Film Badge Dosimetry in Atmospheric Nuclear Tests |author=Committee on Film Badge Dosimetry in Atmospheric Nuclear Tests, National Research Council |pages=24–35 |year=1989 |publisher=National Academies Press |isbn=978-0-3090-4079-2}}{{cite web |url=http://www.dtra.mil/Portals/61/Documents/NTPR/4-Rad_Exp_Rpts/30_DTRA-TR-07-5_Fractionation_Report.pdf |title=Bounding Analysis of Effects of Fractionation of Radionuclides in Fallout on Estimation of Doses to Atomic Veterans DTRA-TR-07-5 |year=2007}}]]

During the first hour after a nuclear explosion, radioactivity levels drop precipitously. Radioactivity levels are further reduced by about 90% after another 7 hours and by about 99% after 2 days. An accurate rule of thumb, applicable in the time-period of days to a few weeks post-detonation which approximates the radioactive dose rate generated by the decay of the myriad of isotopes present in nuclear fallout, is the "7/10 rule".[https://archive.org/details/Radiolog1961 Radiological defense 1961] The rule states that for each 7-fold increase in time the dose rate drops by a factor of 10.{{cite web |url=http://www3.nd.edu/~nsl/Lectures/phys205/pdf/Nuclear_Warfare_9.pdf |title=Radiation Effects of a Nuclear Bomb |publisher=3.nd.edu |access-date=2013-11-30 |archive-date=2013-11-26 |archive-url=https://web.archive.org/web/20131126220402/http://www3.nd.edu/~nsl/Lectures/phys205/pdf/Nuclear_Warfare_9.pdf |url-status=dead }} For example, assuming the fallout process has ended 24 hours post detonation and the dose rate would be lethal if a few hours of exposure occurred, 50 roentgens per hour, then 7 days after detonation the dose rate will be 5 R/hr and 49 days after detonation (7×7 days) the dose rate will be 0.5 R/hr at which point no special precautions would need to be taken and venturing outside into that dose rate for an hour or two would pose a close to negligible health hazard,{{cite web|url=http://nikealaska.org/nuke/fallout.html |title=Understanding Radioactive Fallout |publisher=Nikealaska.org |date=2006-01-07 |access-date=2013-11-30}} thus permitting an evacuation to be done with acceptable safety to a known contamination free zone. Following a surface-burst nuclear detonation, approximately 80 percent of the fallout would be deposited on the ground during the first 24 hours.

Some agencies that promoted "evacuate immediately" guidance as a response to potentially lethal fallout arriving, advice which may have been influenced by these agencies assuming simplistic single wind-driven cigar/Gaussian shaped fallout contours would be representative of reality, have since retracted this advice. This can actually result in higher radiation exposures as it would put people outdoors and in harm's way when the radiation levels would be highest. The Modeling and Analysis Coordination Working Group (MACWG) – which was set up to resolve conflicting advice given by various agencies, has reaffirmed that the best blanket advice that would reduce the number of casualties by the greatest amount is: "Early, adequate sheltering followed by informed, delayed evacuation."

Expert advice published in the 2010 document Planning Guidance for Response to a Nuclear Detonation is to shelter in place, in an area away from building fires, for at least 1 to 2 hours following a nuclear detonation and fallout arriving, and the greatest benefit, assuming personnel are in a building with a high protection factor, is sheltering for no less than 12 to 24 hours before evacuation. Therefore, sheltering for the first few hours can save lives.{{cite web|url=http://www.remm.nlm.gov/nuclearexplosion.htm |title=Nuclear Detonation: Weapons, Improvised Nuclear Devices - Radiation Emergency Medical Management |publisher=Remm.nlm.gov |access-date=2013-11-30}} Indeed, death and injury from local fallout is regarded by experts as the most preventable of all the effects of a nuclear detonation, being simply dependent on if personnel know how to identify an adequate shelter when they see one and enter one quickly, with the number of potential people saved being cited as in the hundreds of thousands.{{cite web|url=https://www.youtube.com/watch?v=ChZUuM-uJ0E |archive-url=https://ghostarchive.org/varchive/youtube/20211221/ChZUuM-uJ0E |archive-date=2021-12-21 |url-status=live|title=Reducing consequences of nuclear detonation |date=18 October 2010 |publisher=YouTube |access-date=2013-11-30}}{{cbignore}}{{cite web|url=https://www.youtube.com/watch?v=ttv1NLf6Cs4 |archive-url=https://ghostarchive.org/varchive/youtube/20211221/ttv1NLf6Cs4 |archive-date=2021-12-21 |url-status=live|title=Brooke Buddemeier, Nuclear Detonation in a Major City |publisher=YouTube |date=2011-06-21 |access-date=2013-11-30}}{{cbignore}}{{cite web |url=http://prod.sandia.gov/techlib/access-control.cgi/2011/119092.pdf |title=Analysis of Sheltering and Evacuation Strategies for a National Capital Region Nuclear Detonation Scenario, Sandia Report, SAND 2011-9092 Unlimited Release Published December 2011. Authors: Larry D. Brandt, Ann S. Yoshimura}}{{cite web |url=http://prod.sandia.gov/techlib/access-control.cgi/2009/093299.pdf |title=Analysis of Sheltering and Evacuation Strategies for an Urban Nuclear Detonation Scenario (Los Angeles) Sandia Report SAND2009-3299 Unlimited Release Printed May 2009, Authors: Larry D. Brandt, Ann S. Yoshimura}} Or even higher if the remaining occupants of the city are made aware of the contaminated areas, by emergency systems, within hours of the event's aftermath.{{Cite book |title=Social Computing, Behavioral-Cultural Modeling and Prediction Lecture Notes in Computer Science Volume 7812, 2013, pp 476-485 Modeling the Interaction between Emergency Communications and Behavior in the Aftermath of a Disaster|volume = 7812|pages = 476–485|doi = 10.1007/978-3-642-37210-0_52|chapter = Modeling the Interaction between Emergency Communications and Behavior in the Aftermath of a Disaster|year = 2013|last1 = Chandan|first1 = Shridhar|last2 = Saha|first2 = Sudip|last3 = Barrett|first3 = Chris|last4 = Eubank|first4 = Stephen|last5 = Marathe|first5 = Achla|last6 = Marathe|first6 = Madhav|last7 = Swarup|first7 = Samarth|last8 = Vullikanti|first8 = Anil Kumar S|isbn = 978-3-642-37209-4}} In 2009 to 2013 a further iteration on sheltering-in-place was made to determine the optimal improvised fallout-shelter-residence-times following a nuclear detonation, with computer analysis, and including a summary of prior studies and guidance. It was found that individuals should quickly get into the best intact building at least under 5 minutes distant in travel time following the detonation and they should stay there for at least 30 minutes before venturing out to find a shelter with a higher protection factor but that is a greater travel time away than 10 minutes.{{cite web|url=https://newatlas.com/survive-nuclear-bomb-shelter/31057/|title=How to survive a nuclear bomb: An update on "Duck and Cover"|website = New Atlas|last = Dodson|first = Brian|date = 12 March 2014}}{{cite web|url=http://www.thejournal.ie/what-to-do-when-theres-an-atomic-bomb-1265502-Jan2014/|title=Where to hide if a nuclear bomb is dropped on your city… |date=18 January 2014 |publisher=Business Insider |via=thejournal.ie}}{{cite web|url=https://www.sciencenews.org/blog/gory-details/nuclear-attack-there%E2%80%99s-no-avoiding-brutal-math|title=In a nuclear attack, there's no avoiding the brutal math|first=Erika|last=Engelhaupt|date=29 January 2014}}{{cite journal|title=Determining optimal fallout shelter times following a nuclear detonation|first=Michael B.|last=Dillon|date=8 March 2014|journal=Proc. R. Soc. A|volume=470|issue=2163|page=20130693|doi=10.1098/rspa.2013.0693|bibcode = 2014RSPSA.47030693D|doi-access=free}} However, although this would be effective in cases where the initial building protection factor is less than about 10, it requires a high degree of individual situational awareness that may be optimistic to assume following the shock of a nuclear detonation. If a building with a PF of 20 or more is nearby, such as the fallout shelters depicted in the film, in the vast majority of fallout circumstances, it would not be advisable to leave it until 3+ hours have elapsed following the initial arrival of the local fallout.

Following a single IND (improvised nuclear device) detonation in the US, the National Atmospheric Release Advisory Center (NARAC) would, within minutes to at most hours, after the detonation have a reliable prediction of the fallout plume size and direction. When armed with this prediction they would then begin attempting to corroborate this with readings from radiation survey meter equipment that would fly over close to the ground in the affected area by means of helicopter or drone (UAV) aircraft on material intelligence gathering missions,[https://archive.org/details/Radiolog1961 Radiological defense 1961. c 18 minutes] which would also follow within tens of minutes to at most hours after the detonation.{{efn |1=As this ground hugging fly over has the potential to be mistaken for airlift rescue attempts, which are common after other natural disasters, survivors should not exit shelter unless absolutely necessary in the time period before being informed of the fallout situation, or alternatively, stay in shelter until sufficient time has elapsed, +24 hrs for a delayed evacuation to take place.}}

Once a general outline and direction of the fallout is determined, disseminating this information to citizens sheltering-in-place would soon follow, by means of loudspeaker, radio, cell phone etc., with a "Fallout App" containing maps for smart phones being regarded as an area of interest so that survivors do not inadvertently evacuate downwind further into harm's way.{{cite web |url=http://www.nae.edu/Publications/Bridge/19804/19892.aspx |title= A Nuclear Explosion in a City or an Attack on a Nuclear Reactor Author: Richard L. Garwin, 2010}}{{cite web |url=http://www.remm.nlm.gov/nuclearexplosion.htm |title=Nuclear Detonation: Weapons, Improvised Nuclear Devices, Communicating After an IND Detonation: Resource for Responders and Officials}} A number of questions the affected public are likely to have after a nuclear detonation have been compiled and pre-answered to help communications in the immediate aftermath.{{cite web|url=http://www.fema.gov/media-library-data/20130726-1919-25045-0618/communicating_in_the_immediate_aftermath__final_june_2013_508_ok.pdf|title=Improvised Nuclear Devices, Communicating in the immediate aftermath. FEMA 2013}}{{Cite book|url=http://www.nap.edu/catalog/18347/nationwide-response-issues-after-an-improvised-nuclear-device-attack-medical|title=Nationwide Response Issues After an Improvised Nuclear Device Attack: Medical and Public Health Considerations for Neighboring Jurisdictions: Workshop Summary|first=Institute of|last=Medicine|date=9 July 2013|doi=10.17226/18347|pmid=24199263|isbn=978-0-309-28601-5}}

{{See also|National Response Scenario Number One}}

In respect to the other non-lethal weapon effects from an IND detonated on or near the surface, the detonation's blast wave would likely produce a momentary electric grid blackout due to the loss of a large portion of a city's electrical equipment drawing power/electrical load, while the electromagnetic pulse (EMP) from a surface/ground-burst explosion would cause little damage outside the blast area, so cell phone towers that survive the blast should be capable of carrying communications. But if communications during the 9/11 attacks or after a major hurricane are anything to go by and the cell phone network towers survive, the service would be overloaded (a mass call event) and thereby made useless soon after; however, if prior arrangements between the cell network and emergency responders are made to give them priority and bar access to all other individuals, then it may be an effective service.

The Civil Defense (CD) shelters, as depicted in the film, were stocked for such an eventuality. They contained among other things, at least one ruggedized CDV-715 radiation survey meter and one CD emergency radio receiver which would respectively be used to facilitate a safe delayed evacuation, regardless of outside help though if communications continued, the radio receiver was to inform them of the outside situation as it developed.

{{See also|Radioactive contamination#Social and psychological effects|Cobalt bomb#decontamination|Decontamination foam|Background radiation#Areas with high natural background radiation|Victory garden|Pico hydro|Wood Gas Generator|Bikini Atoll#Current habitable state}}

The dubious assumption that "only the cockroaches" would survive the post-war fallout environment was frequently used in an attempt to criticize Duck and Cover during the height of the Cold War, contextually at a time when discussion of a total war involved the much greater US-Soviet arsenal of nuclear weapons that were then in existence. However even at that time, this assumption was shown to be misled, as scientifically detailed in areas including the 1988 book Would the Insects Inherit the Earth and Other Subjects of Concern to Those Who Worry About Nuclear War.{{cite journal|title = Internal dose following a major nuclear war|journal = Health Physics|last1 = Peterson |first1 = Kendall R.|last2= Shapiro|first2= Charles S|date = January 1992|volume= 62|issue = 1|pages = 29–40|doi = 10.1097/00004032-199201000-00004|pmid = 1727410| s2cid=19380284 }}{{cite journal|url=https://journals.lww.com/health-physics/Abstract/1960/04000/Cobalt_60_Bombs.8.aspx|title=Cobalt-60 Bombs: Health Physics|journal=Health Physics|date=April 1960|volume=4|issue=1|pages=52–54|last1=Dunning|first1=G. M.|doi=10.1097/00004032-196004000-00008|pmid=13725069}}{{cite journal|title=Estimates of doses from global fallout|first1=André|last1=Bouville|first2=Steven L.|last2=Simon|first3=Charles W.|last3=Miller|first4=Harold L.|last4=Beck|first5=Lynn R.|last5=Anspaugh|first6=Burton G.|last6=Bennett|date=1 May 2002|journal=Health Physics|volume=82|issue=5|pages=690–705|pmid=12003019|doi=10.1097/00004032-200205000-00015|s2cid=21009228}}

In material terms, the primary life-threatening risk survivors and downwinders could face in the long-term after a nuclear explosion or war, is the "nuclear famine" issue, the potential continuation of hostilities by conventional warfare and radioactive contamination of the food and water supplies, disrupting the normal distribution and consumption, of these vital goods.

Cold War continuity of government planners and civil defense organizations in general have always had this disruption, or "nuclear famine" issue in mind, as widespread infrastructure destruction producing starvation conditions was also seen during and after WWII. Papers such as On Reorganizing After Nuclear Attack,{{cite web |url=http://www.rand.org/pubs/papers/P3764.html|title=On Reorganizing After Nuclear Attack|date=1 January 1968|last1=Brown|first1=William Morle}} and Survival of the relocated population of the U.S. after a nuclear attack by Nobel Prize winner, Eugene Wigner, detail the thought and attention that went into long-term survival, relocation and reconstruction.{{cite book |url=https://apps.dtic.mil/dtic/tr/fulltext/u2/a026362.pdf |archive-url=https://web.archive.org/web/20200111214800/https://apps.dtic.mil/dtic/tr/fulltext/u2/a026362.pdf |url-status=live |archive-date=January 11, 2020 |title=Survival of the relocated population of the U.S. after a nuclear attack |year=1976 |first1=Carsten M. |last1=Haaland |first2=Conrad V. |last2=Chester |first3=Eugene P. |last3=Wigner }}

Numerous human and agricultural decontamination countermeasures exist for the two most persistent and biologically significant isotopes,{{cite journal |doi=10.1016/0048-9697(93)90376-H |title=Agricultural countermeasures following deposition of radioactivity after a nuclear accident |journal=Science of the Total Environment |volume=137 |issue=1–3 |pages=31–48 |year=1993 |last1=Segal |first1=M.G. |bibcode=1993ScTEn.137...31S }}{{cite journal |doi=10.1016/0048-9697(93)90391-I |pmid=8248770 |title=Chemical methods for reduction of the transfer of radionuclides to farm animals in semi-natural environments |journal=Science of the Total Environment |volume=137 |issue=1–3 |pages=235–248 |year=1993 |last1=Hove |first1=K. |bibcode=1993ScTEn.137..235H }} cesium-137, strontium-90 and long-lived fallout contamination in general, with the most visible and immediate act that will prevent a potentially large dose to the public, taking the form of using shielded bulldozers to skim off the layer of topsoil that the fallout had settled on, a restorative{{cite report |doi=10.2172/7148724 |title=The Long-Term Problems of Contaminated Land: Sources, Impacts and Countermeasures|first=C. F. Iii|last=Baes|date=1 November 1986|osti = 7148724|url=https://digital.library.unt.edu/ark:/67531/metadc1418307/|doi-access=free}}{{cite web|url=http://www-naweb.iaea.org/nafa/faqs-food-agriculture.html|title=Joint Division Questions & Answers - Nuclear Emergency Response for Food and Agriculture, NAFA|author=Joint FAO/IAEA Programme|website=iaea.org}}International Atomic Energy Agency (IAEA), 2000 – Technology & Engineering – restoration of environments with radioactive residues: papers and discussions, 697 pages. practice that was fielded upon the creation of Lake Chagan.{{cite AV media|url=https://www.youtube.com/watch?v=XEqYroQEtA8 |archive-url=https://ghostarchive.org/varchive/youtube/20211221/XEqYroQEtA8 |archive-date=2021-12-21 |url-status=live|title=Born of Nuclear Blast: Russia's Lakes of Mystery|date=November 28, 2010|work=YouTube}}{{cbignore}} The creation of human decontamination tents at the entrances of buildings and when lower levels of risk exist, the use of clean room air showers as a form of contamination control to prevent the spread of radionuclides that adhere to dust, into building interiors, would also be advisable to reduce the elevated risk of radiation induced cancer that would otherwise occur. Air showers may be paired with electrostatic precipitators to attract the dust to collection plates, forestalling a re-suspension that may otherwise be inhaled.{{cite journal |doi=10.1109/TIA.2013.2263782 |title=Development of an Electrostatic Precipitator to Remove Martian Atmospheric Dust from ISRU Gas Intakes During Planetary Exploration Missions |journal=IEEE Transactions on Industry Applications |volume=49 |issue=6 |pages=2388–2396 |year=2013 |last1=Clements |first1=J. Sidney |last2=Thompson |first2=Samuel M. |last3=Cox |first3=Nathanael D. |last4=Johansen |first4=Michael R. |last5=Williams |first5=Blakeley S. |last6=Hogue |first6=Michael D. |last7=Lowder |first7=M. Loraine |last8=Calle |first8=Carlos I. |hdl=2060/20110015825 |hdl-access=free }}{{cite book |doi=10.1117/12.683231 |chapter=Comparative mirror cleaning study: A study on removing particulate contamination |title=Optical Systems Degradation, Contamination, and Stray Light: Effects, Measurements, and Control II |volume=6291 |page=629107 |year=2006 |last1=Houston |first1=Karrie D. |hdl=2060/20080040790 |s2cid=119788965 |editor1-last=Uy |editor1-first=O. Manuel |editor2-last=Straka |editor2-first=Sharon A |editor3-last=Fleming |editor3-first=John C |editor4-last=Dittman |editor4-first=Michael G }} Moreover use of the open access radioecology research on decontamination and conventional agriculture in the Chernobyl-Polesie State Radioecological Reserve{{cite journal |doi=10.1016/j.jenvrad.2016.02.003 |pmid=27018344 |title=Thirty years after the Chernobyl accident: What lessons have we learnt? |journal=Journal of Environmental Radioactivity |volume=157 |pages=77–89 |year=2016 |last1=Beresford |first1=N.A. |last2=Fesenko |first2=S. |last3=Konoplev |first3=A. |last4=Skuterud |first4=L. |last5=Smith |first5=J.T. |last6=Voigt |first6=G. |doi-access=free |bibcode=2016JEnvR.157...77B }}[https://books.google.com/books?id=uElVyTd84xEC&dq=giese+salt+afcf&pg=PA193 Chernobyl: Catastrophe and Consequences By Jim Smith, Nicholas A. Beresford. 5 Application of countermeasures pg 191] and around the Fukushima accident,{{cite web |url=http://fukushima.jaea.go.jp/english/decontamination/pdf/2-2-2%20Decontamination%20Technologies.pdf |archive-url=https://web.archive.org/web/20161121045235/http://fukushima.jaea.go.jp/english/decontamination/pdf/2-2-2%20Decontamination%20Technologies.pdf |archive-date=November 21, 2016 |title=Report on the results of the decontamination. Analysis and Evaluation of the Results of the Decontamination Model Project, decontamination technologies }} would both be implemented in the event of any widespread fallout contamination, with particular emphasis on bioremediation of radionuclides from soil and aquifers.{{cite web |url=https://news.virginia.edu/content/uva-undergraduate-researcher-studies-sunflowers-power-clean-soil|archive-url=https://web.archive.org/web/20150215080519/https://news.virginia.edu/content/uva-undergraduate-researcher-studies-sunflowers-power-clean-soil|archive-date=15 February 2015|title=U.Va. Undergraduate Researcher Studies Sunflowers' Power to Clean Up Soil - UVA Today|date=15 February 2015}} Although less of a hazard than external exposure, internal decontamination, that may be required after assessment in a whole-body counting session, in the long term may, as is now, be conducted with binding-and-excretion promoting chelation therapy, with ammonium-ferric-hexacyano-ferrate (AFCF)/"Giese salt", Radiogardase and DPTA all proven effective.{{cite book |first1=T. Jan |last1=Cerveny |chapter= Treatment of Internal Radionuclide Contamination |chapter-url=https://ke.army.mil/bordeninstitute/published_volumes/nuclearwarfare/chapter4/chapter4.pdf |archive-url=https://web.archive.org/web/20170125171315/https://ke.army.mil/bordeninstitute/published_volumes/nuclearwarfare/chapter4/chapter4.pdf |archive-date=January 25, 2017 |pages=56–68 |title=Medical Consequences of Nuclear Warfare }}

Comparable binding/chelation treatment systems, developed and deployed due to the Fukushima reactor-water decontamination mandate,{{cite web |url=http://www.tepco.co.jp/en/decommision/planaction/alps/index-e.html|title=Contaminated Water Treatment - TEPCO|website=www.tepco.co.jp}} includes the mobile reverse osmosis Landysh water treatment ship, the zeolite-rock based "Actiflo",{{cite web |url=https://www.power-eng.com/articles/npi/print/volume-6/issue-2/case-study/veolia-arevas-water-decontamination-system.html|title=Veolia & Areva's water decontamination system|website=www.power-eng.com}} the "SARRY" ion exchange cesium removal system, based on silicotitanate "IONSIV" crystalline rock,{{cite web |url=http://tech.nikkeibp.co.jp/dm/english/NEWS_EN/20111223/202955/|title=Toshiba, IHI Develop Transportable Treatment System for Radiation-tainted Water|first=Nikkei|last=Xtech|date=9 May 2024 }}http://archive.wmsym.org/2014/papers/14018.pdf {{Bare URL PDF|date=March 2022}}{{cite report |doi=10.2172/469131 |title=Development and properties of crystalline silicotitanate (CST) ion exchangers for radioactive waste applications |osti=469131 |year=1997 |last1=Miller |first1=J.E. |last2=Brown |first2=N.E. |url=https://digital.library.unt.edu/ark:/67531/metadc674378/ }}{{Cite book |url=https://www.nap.edu/read/9959/chapter/7 |title=Alternatives for High-Level Waste Salt Processing at the Savannah River Site|date=30 October 2000|doi=10.17226/9959|isbn=978-0-309-07194-9|author1=Board on Chemical Sciences and Management Technology|author2=Board on Radioactive Waste Management|author3=Committee on Cesium Processing Alternatives for High-Level Waste at the Savannah River Site}}{{cite journal |title=A Comparison of Crystalline Silicotitanate and Ammonium Molybdophosphate-Polyacrylonitrile Composite Sorbent for the Separation of Cesium from Acidic Waste|first1=T. A.|last1=Todd|first2=V. N. |last2=Romanovskiy|date=1 July 2005|journal=Radiochemistry|volume=47|issue=4|pages=398–402 |doi=10.1007/s11137-005-0109-3|s2cid=94385909}} and most recently the 62 multi-nuclide removal system (NURES), frequently referred to as the Advanced Liquid Processing System (ALPS).http://www.world-nuclear-news.org/WR_Fukushima_water_treatment_stepping_up_1503121.html Fukushima water treatment stepping up{{cite web |url=http://www.neimagazine.com/features/featurethe-ultimate-water-treatment-system|title=The ultimate water treatment system - Nuclear Engineering International|website=www.neimagazine.com|date=August 2012 }}{{cite conference |last1=Tusa |first1=Esko |year=2014 |title=Efficiency of Fortum's CsTreat® and SrTreat® in cesium and strontium removal in Fukushima Daiichi NPP |url=https://inis.iaea.org/search/search.aspx?orig_q=RN:46123241 |conference=Proceedings of the European Nuclear Conference - ENC 2014 }}{{cite book |citeseerx=10.1.1.495.5570 |title=Use of nuclide removal system (NURES) for clean-up of different waste liquids |first1=E. |last1=Tusa }}{{cite web|url=http://www.fukuleaks.org/web/?p=15046|title=Fukushima ALPS System Secret Revealed}} In 2016 tritiated water also began to be filtered.{{cite web|url=http://www.world-nuclear.org/focus/fukushima/fukushima-accident.aspx|archive-url=https://web.archive.org/web/20170705074527/http://www.world-nuclear.org/focus/fukushima/fukushima-accident.aspx|archive-date=5 July 2017|title=Fukushima Accident - World Nuclear Association|date=5 July 2017}}{{cite journal|title=Technical and economic characteristics of processes for water detritiation by chemical isotope exchange in the water-hydrogen system|first1=A. I. |last1=Kostylev|first2=I. S.|last2=Ledovskoi|first3=E. P.|last3=Magomedbekov|first4=M. B. |last4=Rozenkevich|first5=Yu. A.|last5=Sakharovsky|first6=I. L.|last6=Selivanenko|first7=A. I. |last7=Sobolev|first8=S. N.|last8=Florya|date=1 September 2014 |journal=Radiochemistry |volume=56 |issue=5 |pages=529–534 |doi=10.1134/s1066362214050130|s2cid=95581336 }}

Researchers at the American Chemical Society have further suggested that aquaponics{{cite web|url=https://www.acs.org/content/acs/en/pressroom/newsreleases/2015/november/could-humans-survive-decades-in-a-fallout-shelter-video.html|title=Could humans survive decades in a fallout shelter? (video) - American Chemical Society}} would be an ideal socially-acceptable solution in the post-contamination environment, as it does not use soil to grow fish and vegetables,{{usurped|1=[https://web.archive.org/web/20180401040750/http://www.rhodeislandaquaponics.com/ The Malthus prototype]}} thus completely alleviating the radiophobia surrounding food that always follows long-lived contamination incidents. Others who have approached the food problem from a far more extreme view, assuming far worse events such as comet impacts (as discussed in the book Feeding Everyone No Matter What) have suggested: natural-gas-digesting bacteria, the most well known being methylococcus capsulatus, which is presently used as a feed in fish farming;- [http://www.unibio.dk/] "UniBio A/S – turns NG to fish food" bark bread, a long-standing famine food using the edible inner bark of trees (once a part of Scandinavian history during the Little Ice Age); and the expansion of leaf protein concentrate and larger scale wood digesting fungiculture for fungal protein, with the most common of which being shiitake mushrooms and honey fungi, as they do not need sunlight or soil to grow.Hazeltine, B. & Bull, C. 2003 Field Guide to Appropriate Technology. San Francisco: Academic Press. More advanced techniques mentioned, which are not presently economical, also include variations of wood or cellulosic biofuel production (which typically already creates edible sugars/xylitol from inedible cellulose) as an intermediate product before the final step of alcohol generation.{{Cite web |url=https://www.plant.ca/general/biofuel-process-to-develop-sugar-substitute-cellulose-ethanol-304/ |title=Biofuel process to develop sugar substitute, cellulose ethanol. SunOpta BioProcess Inc. 2010 |access-date=2018-10-29 |archive-date=2018-10-19 |archive-url=https://web.archive.org/web/20181019042641/https://www.plant.ca/general/biofuel-process-to-develop-sugar-substitute-cellulose-ethanol-304/ |url-status=dead }}{{cite journal | last1 = Langan | first1 = P. | last2 = Gnanakaran | first2 = S. | last3 = Rector | first3 = K. D. | last4 = Pawley | first4 = N. | last5 = Fox | first5 = D. T. | last6 = Chof | first6 = D. W. | last7 = Hammelg | first7 = K. E. | year = 2011 | title = Exploring new strategies for cellulosic biofuels production | journal = Energy Environ. Sci. | volume = 4 | issue = 10| pages = 3820–33 | doi=10.1039/c1ee01268a| s2cid = 94766888 }}

Some historians and documentaries, including science historian Melissa Smith in a 2010 article for The British Journal for the History of Science and the film 1982 The Atomic Cafe, have described "duck and cover" advice as propaganda.

In U.S. Army training, soldiers are taught to immediately fall down, covering face and hands in much the same way as is described by the advice to duck and cover.{{cite web |url=http://www.globalsecurity.org/wmd/library/policy/army/fm/3-4/Ch4.htm#para1 |title=Field manual FM 3-4 Chapter 4. "Dropping immediately and covering exposed skin provide[s] protection against blast and thermal effects."..."Immediately drop facedown. A log, a large rock, or any depression in the earth's surface provides some protection. Close eyes. Protect exposed skin from heat by putting hands and arms under or near the body and keeping the helmet on. Remain facedown until the blast wave passes and debris stops falling. Stay calm, check for injury, check weapons and equipment damage and prepare to continue the mission."}}

The exercises of Cold War civil defense were described by historian Guy Oakes in 1994 as having less practical use than psychological use: to keep the danger of nuclear war high on the public mind, while also attempting to assure the American people that something could be done to defend against nuclear attack.Oakes, Guy. The Imaginary War: Civil Defense and Cold War Culture. 1994, Oxford University Press. {{ISBN|0-19-509027-6}}, pp. 66–68

{{see also|Tornado drill}}

File:Tornado drill.jpg. Similar to other evidence based safety drills, they teach effective countermeasures and therefore increase survival rates if/when a tornado hits.]]

Ducking and covering does have certain applications in other, more natural disasters. In states prone to tornadoes, school children are urged to "duck and cover" against a solid inner wall of a school, if time does not permit seeking better shelter—such as a storm cellar—during a tornado warning. The tactic is also widely practiced in schools in states along the West Coast of the United States, where earthquakes are commonplace. Ducking and covering in either scenario would theoretically afford significant protection from falling or flying debris.

{{see also|Nuclear bunker buster}}

In an earthquake, which are generally of a natural tectonic plate origin (although they can be artificially generated by the detonation of a nuclear explosive device in which sufficient energy is transmitted into the ground, with an extreme case to serve as an example of this phenomenon being the Operation Grommet Cannikin test of the 5 megaton W71 warhead exploded deep underground on Amchitka Island in 1971, which produced a seismic shock quake of 7.0 on the Richter magnitude scale) people are encouraged, regardless of the cause of the quake, to "drop, cover and hold on": to get underneath a piece of furniture, cover their heads and hold on to the furniture. This advice also encourages people not to run out of a shaking building, because a large majority of earthquake injuries are due to broken bones from people falling and tripping during shaking. While it is unlikely that "drop, cover and hold on" will protect against a building collapse, in earthquake-prone areas in the United States building codes require that buildings withstand quakes up to an expected magnitude enough to allow evacuation after shaking stops.{{cite web |url=http://www.livescience.com/13962-tornado-safety-building-codes.html |title=Why Aren't There Tornado Safety Building Codes?|website=Live Science|date=29 April 2011 }}{{cite web |url=http://mceer.buffalo.edu/infoservice/Reference_Services/usCodes.asp#3 |title=Directory of Building Codes & Regulations: City & State Directory}}{{cite web |url=http://mceer.buffalo.edu/infoservice/Reference_Services/USInternationalCodes.asp |title=U.S. & International Seismic Codes}}{{cite web |url=http://www.nehrp.gov/library/guidance_new.htm |title=National Earthquake Hazards Reduction Program - Comparison of U.S. and Chilean Building Code Requirements and Seismic Design Practice 1985-2010}} and thus a building collapse of these structures (even during an earthquake) is rare. "Drop, cover and hold on" may not be appropriate for all locations or building types, but the Red Cross advises{{cite web|url=http://www.redcross.org/static/file_cont164_lang0_71.pdf |title=Drop, Cover and Hold On – American Red Cross drill (pdf file) |archive-url=https://web.archive.org/web/20060316024324/http://www.redcross.org/static/file_cont164_lang0_71.pdf |archive-date=March 16, 2006 }} it is the appropriate emergency response to an earthquake in the United States.

General

{{colbegin}}

• A Day Called X a dramatized 1957 CBS documentary following the evacuation drill of the entire city of Portland, Oregon per Civil Defense protocol, in response to the RADAR detection of an en-route Soviet nuclear bomber force.
• Abo Elementary School - Underground school built in the 1960s, used until the 1990s
• Air-raid shelter
• Atomic Bomb Casualty Commission - upon whose work the writers of Duck and Cover heavily borrowed.
• Blast shelter
• Civil Defense Geiger counters
• Comparison of Chernobyl and other radioactivity releases
• CONELRAD
• Desert Rock exercises
• Enewetak Atoll
• High-altitude nuclear explosion
• List of artificial radiation belts
• List of nuclear weapons#Soviet Union/Russia
• Mass-casualty incident
• Mount Weather Emergency Operations Center
• National Response Scenario Number One
• Nevada Test Site
• Novaya Zemlya
• Nth Country Experiment
• Nuclear arms race
• Nuclear Emergency Support Team
• Nuclear terrorism
• Nuclear War Survival Skills
• Nuclear winter
• Operation Teapot
• Pacific Proving Grounds
• Pechora–Kama Canal
• Project SUNSHINE
• Radiobiology
• Radioecology
• Reactor-grade plutonium
• Semipalatinsk Test Site
• Stop, drop and roll - Advice for when one is on fire and no other means of extinguishing the flames are available.
• Subsidence crater
• The Geochemist's Workbench

{{colend}}

Long-term survival

{{Colbegin}}

• Aeroponics agriculture with low water usage requirements
• Amateur radio emergency communications - post disaster networking
• Anaerobic waste digestion for fuel production
• Anti-flash white paint
• Appropriate technology
• Autonomous building homes
• Bioconversion of biomass to mixed alcohol fuels
• BIOS-3
• Chernobyl Exclusion Zone
• David J. Gingery DIY author of machine tool books
• Earthship homes
• Emergency preparedness
• Enriched CO2 greenhouse air agriculture
• Ex-Rad a medicinal product being tested for its effects at increasing human radioresistance
• Fallout Protection
• Hibakusha - survivors of prompt radiation with comparatively little to no fallout exposure
• Hurricane-proof building
• HurriQuake
• Preparedness
• Primitive skills
• Red Forest - heavily contaminated forest, with controlled biomass power burning suggested to prevent a re-suspension of fallout that would occur following a wildfire.
• Remanufacturing
• Removal of ions and dissolved substances from water
• Repurposing
• Seed bank
• Self-sustainability
• Whitewash paint

{{colend}}

Informational notes

{{Notelist}}

Citations

{{Reflist}}

{{Spoken Wikipedia|Duck and cover.ogg|date=2005-04-14}}

• [https://www.youtube.com/watch?v=gqCxcnhNAeQ Duck and Cover! film at YouTube]
• {{usurped|1=[https://web.archive.org/web/20060316024324/http://www.redcross.org/static/file_cont164_lang0_71.pdf Drop, Cover, and Hold On]}} – American Red Cross drill (PDF-file)
• [http://www.conelrad.com/duckandcover/cover.php?turtle=01 Production history of the film Duck and Cover] {{Webarchive|url=https://web.archive.org/web/20201127013939/http://www.conelrad.com/duckandcover/cover.php?turtle=01 |date=2020-11-27 }}
• [https://archive.org/details/DuckandC1951 Prelinger Archive] has Duck and Cover! available for download or streaming.
• {{IMDb title|qid=Q499144|title=Duck and cover}}
• [http://www.nukefallout.com/myths.html PROPAGANDA lie no.5 "Telling school children to duck under their desks and cover their heads is a ludicrously ineffective piece of advice"]
• {{usurped|1=[https://web.archive.org/web/20170307092351/http://collections.stanford.edu/atomicenergy/bin/detail?fileID=394848179 Biological and environmental effects of nuclear war. Hearings before the Special Subcommittee on Radiation of the Joint Committee on Atomic Energy 1959.PDF]}}
• [https://www.ready.gov/nuclear-explosion Nuclear Explosion {{!}} Ready.gov] - DHS Ready Campaign includes nuclear preparation in 2018

{{DEFAULTSORT:Duck And Cover}}

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