Editing Nuclear fallout (section)

===Short term===
{{Further|LD50|l1=LD<sub>50</sub>}}
{{More citations needed section|date=December 2024}}
[[File:Fallout shelter sign on a building.JPG|thumb|[[Fallout shelter]] sign on a building in [[New York City]]]]
The dose that would be lethal to 50% of a population is a common parameter used to compare the effects of various fallout types or circumstances. Usually, the term is defined for a specific time, and limited to studies of acute lethality. The common time periods used are 30 days or less for most small laboratory animals and to 60 days for large animals and humans. The LD<Sub>50</Sub> figure assumes that the individuals did not receive other injuries or medical treatment.

In the 1950s, the LD<Sub>50</Sub> for gamma rays was set at 3.5 Gy, while under more dire conditions of war (a bad diet, little medical care, poor nursing) the LD<Sub>50</Sub> was 2.5 Gy (250 rad). There have been few documented cases of survival beyond 6 Gy. One person at [[Chernobyl disaster|Chernobyl]] survived a dose of more than 10 Gy, but many of the persons exposed there were not uniformly exposed over their entire body. If a person is exposed in a non-homogeneous manner then a given dose (averaged over the entire body) is less likely to be lethal. For instance, if a person gets a hand/low arm dose of 100 Gy, which gives them an overall dose of 4 Gy, they are more likely to survive than a person who gets a 4 Gy dose over their entire body. A hand dose of 10 Gy or more would likely result in loss of the hand. A [[United Kingdom|British]] industrial [[radiographer]] who was estimated to have received a hand dose of 100 Gy over the course of his lifetime lost his hand because of [[radiation dermatitis]].<ref>{{cite journal|url=http://oem.bmj.com/content/51/10/713.full.pdf|title=Death of a classified worker probably caused by overexposure to gamma radiation|journal=British Medical Journal|year=1994|volume=54|pages=713–718|access-date=2016-05-22|archive-date=2022-01-25|archive-url=https://web.archive.org/web/20220125090735/https://oem.bmj.com/content/oemed/51/10/713.full.pdf|url-status=live}}</ref>  Most people become ill after an exposure to 1 Gy or more. [[Fetus]]es are often more vulnerable to radiation and may [[miscarriage|miscarry]], especially in the first [[Trimester (pregnancy)|trimester]].

Because of the large amount of short-lived fission products, the activity and radiation levels of nuclear fallout decrease very quickly after being released; it is reduced by 50% in the first hour after a detonation,<ref>{{Cite web |title=Fallout from a Nuclear Detonation: Description and Management - Radiation Emergency Medical Management |url=https://remm.hhs.gov/nuclearfallout.htm |access-date=2024-08-11 |website=remm.hhs.gov}}</ref> then by 80% during the first day. As a result, early [[Human decontamination|gross decontamination]], such as removing contaminated articles of outer clothing, is more effective than delayed but more thorough cleaning.<ref>{{Cite web |title=Fallout from a Nuclear Detonation: Description and Management - Radiation Emergency Medical Management |url=https://remm.hhs.gov/nuclearfallout.htm |access-date=2024-08-11 |website=remm.hhs.gov}}</ref> Most areas become fairly safe for travel and decontamination after three to five weeks.<ref>{{Cite book|title=The Nature of Radioactive Fallout and Its Effects on Man: Hearings Before the Special Subcommittee on Radiation of the Joint Committee on Atomic Energy, Congress of the United States, Eighty-fifth Congress, First Session|last=Joint Committee on Atomic Energy|first=US Congress|publisher=U.S. Government Printing Office|year=1957|url=https://books.google.com/books?id=cveGUvsA4kIC&q=nuclear+fallout+tropospheric%2C+of+1+to+30+days&pg=PA1351|pages=1351|access-date=2021-10-21|archive-date=2022-01-25|archive-url=https://web.archive.org/web/20220125090735/https://books.google.com/books?id=cveGUvsA4kIC&q=nuclear+fallout+tropospheric%2C+of+1+to+30+days&pg=PA1351|url-status=live}}</ref>

One hour after a surface burst, the radiation from fallout in the [[Subsidence crater|crater]] region is 30 grays per hour (Gy/h).{{Clarify|date=February 2008}} Civilian [[dose rate]]s in peacetime range from 30 to 100 μGy per year.


For [[nuclear weapon yield|yields]] of up to 10 [[kiloton|kt]], prompt radiation is the dominant producer of casualties on the battlefield. Humans receiving an acute incapacitating dose (30 Gy) have their performance degraded almost immediately and become ineffective within several hours. However, they do not die until five to six days after exposure, assuming they do not receive any other injuries. Individuals receiving less than a total of 1.5 Gy are not incapacitated. People receiving doses greater than 1.5 Gy become disabled, and some eventually die.

A dose of 5.3 Gy to 8.3 Gy is considered lethal but not immediately incapacitating. Personnel exposed to this amount of radiation have their cognitive performance degraded in two to three hours,<ref>[https://web.archive.org/web/20170125171152/https://ke.army.mil/bordeninstitute/published_volumes/nuclearwarfare/chapter1/chapter1.pdf NUCLEAR EVENTS AND THEIR CONSEQUENCES  by the Borden institute. Chapter 1]</ref><ref>[https://web.archive.org/web/20161227080318/https://ke.army.mil/bordeninstitute/published_volumes/nuclearwarfare/chapter7/chapter7.pdf NUCLEAR EVENTS AND THEIR CONSEQUENCES  by the Borden institute. Chapter 7 BEHAVIORAL AND NEUROPHYSIOLOGICAL CHANGES WITH EXPOSURE TO IONIZING RADIATION ]</ref> depending on how physically demanding the tasks they must perform are, and remain in this disabled state at least two days. However, at that point they experience a recovery period and can perform non-demanding tasks for about six days, after which they relapse for about four weeks. At this time they begin exhibiting symptoms of [[radiation poisoning]] of sufficient severity to render them totally ineffective. Death follows at approximately six weeks after exposure, although outcomes may vary.