A micromort (from micro- and mortality) is a unit of risk defined as one-in-a-million chance of death.[1][2] Micromorts can be used to measure riskiness of various day-to-day activities. A microprobability is a one-in-a million chance of some event; thus a micromort is the microprobability of death. The micromort concept was introduced by Ronald A. Howard who pioneered the modern practice of decision analysis.[3]

Micromorts for future activities can only be rough assessments as specific circumstances will always have an impact. However past historical rates of events can be used to provide a ball-park, average figure.

Sample values


Death from Context Time period N deaths N population Micromorts per unit of exposure Reference
All causes England and Wales 2012 499,331 56,567,000 24 per day
8,800 per year
ONS Deaths[4] Table 5.
All causes Canada 2011 242,074 33,476,688 20 per day
7,200 per year
Statistics Canada[5]
All causes US 2010 2,468,435 308,500,000 22 per day
8,000 per year
CDC Deaths[6] Table 18.
Non-natural cause England and Wales 2012 17,462 56,567,000 0.8 per day
300 per year
ONS Deaths[4] Table 5.19.
Non-natural cause US 2010 180,000 308,500,000 1.6 per day
580 per year
CDC Deaths[6] Table 18
Non-natural cause (excluding suicide) England and Wales 2012 12,955 56,567,000 0.6 per day
230 per year
ONS Suicides[7]
Non-natural cause (excluding suicide) US 2010 142,000 308,500,000 1.3 per day
460 per year
CDC Deaths[6] Table 18.
All causes – first day of life England and Wales 2007 430 per first day of life Walker, 2014[8]
All causes - first year of life US 2013 16.7 per day
6100 per year
CDC Life Tables[9]
Blastland & Spiegelhalter, 2014[10]
Murder/homicide England and Wales 2012/13 551 56,567,000 10 per year ONS Crime[11]
Homicide Canada 2011 527 33,476,688 15 per year Statistics Canada[12]
Murder and non-negligent manslaughter US 2012 14,173 292,000,000 48 per year FBI[13] Table 16

Leisure and sport

Death from Context Time period N deaths N exposure Micromorts per unit of exposure Reference
Scuba diving UK: BSAC members 1998–2009 75 14,000,000 dives 5 per dive BSAC[14]
Scuba diving UK: non-BSAC 1998–2009 122 12,000,000 dives 10 per dive BSAC[14]
Scuba diving US – insured members of DAN 2000–2006 187 1,131,367 members 164 per year as member of DAN
5 per dive
DAN[15] p75
Skiing US 2008/9 39 57,000,000 days skiing 0.7 per day Ski-injury.com[16]
Skydiving US 2000–2016 413 48,600,000 jumps 8 per jump USPA[17]
Skydiving UK 1994–2013 41 4,864,268 jumps 8 per jump BPA[18]
Running marathon US 1975–2004 26 3,300,000 runs 7 per run Kipps C 2011[19]
Base-jumping Kjerag Massif, Norway 1995–2005 9 20,850 jumps 430 per jump Soreide 2007[20]
Mountaineering Ascent to Matterhorn 1981–2011 213 about 75,000 ascents

(about 2500 per year)

about 2840 per ascent attempt Bachmann 2012[21]
Mountaineering Ascent to Mt. Everest 1922–2012 223 5,656 successful ascents 37,932 per ascent attempt NASA 2013[22]


Activities that increase the death risk by roughly one micromort, and their associated cause of death:

  • Travelling 6 miles (9.7 km) by motorbike (accident)[23]
  • Travelling 17 miles (27 km) by walking (accident)[24]
  • Travelling 10 miles (16 km)[25] (or 20 miles (32 km))[24] by bicycle (accident)
  • Travelling 230 miles (370 km) by car (accident)[23] (or 250 miles)[24]
  • Travelling 1000 miles (1600 km) by jet (accident)[25]
  • Travelling 6000 miles (9656 km) by train (accident)[23]
  • Travelling 12,000 miles (19,000 km) by jet in the United States (terrorism)[26]


Increase in death risk for other activities on a per event basis:

Value of a micromort

Willingness to pay

An application of micromorts is measuring the value that humans place on risk: for example, one can consider the amount of money one would have to pay a person to get him or her to accept a one-in-a-million chance of death (or conversely the amount that someone might be willing to pay to avoid a one-in-a-million chance of death). When put thus, people claim a high number but when inferred from their day-to-day actions (e.g., how much they are willing to pay for safety features on cars) a typical value is around $50 (in 2009).[31][32] However utility functions are often not linear, i.e. the more a person has already spent on their safety the less they are willing to spend to further increase their safety. Therefore, the $50 valuation should not be taken to mean that a human life (1 million micromorts) is valued at $50,000,000. Furthermore, the local linearity of any utility curve means that the micromort is useful for small incremental risks and rewards, not necessarily for large risks.[32]

Value of a statistical life

Government agencies use a nominal Value of a Statistical Life (VSL) – or Value for Preventing a Fatality (VPF) – to evaluate the cost-effectiveness of expenditure on safeguards. For example, in the UK the VSL stands at £1.6 million for road improvements.[33] Since road improvements have the effect of lowering the risk of large numbers of people by a small amount, the UK Department for Transport essentially prices a reduction of 1 Micromort at £1.60 (US$2.70). The US Department of Transportation uses a VSL of US$6.2 million, pricing a Micromort at US$6.20.[34]

Chronic risks

Micromorts are best used to measure the size of acute risks, i.e. immediate deaths. Risks from lifestyle, exposure to air pollution and so on are chronic risks, in that they do not kill straight away, but reduce life expectancy. Ron Howard included such risks in his original 1979 work,[25] for example an additional one micromort from …

  • Drinking 0.5 liter of wine (cirrhosis of the liver)[25]
  • Smoking 1.4 cigarettes (cancer, heart disease)[25]
  • Spending 1 hour in a coal mine (black lung disease)[25]
  • Spending 3 hours in a coal mine (accident)[25]
  • Living 2 days in New York or Boston in 1979 (air pollution)[25]
  • Living 2 months with a smoker (cancer, heart disease)[25]
  • Drinking Miami water for 1 year (cancer from chloroform)[25]
  • Eating 100 charcoal-broiled steaks (cancer from benzopyrene)[25]
  • Traveling 6000 miles (10,000 km) by jet (cancer due to increased background radiation)[35]

Such risks are better expressed using the related concept of a microlife.

See also


  1. ^ Fry AM, et al. Micromorts—what is the risk?. 2016-02. Accessed 2016-07-30.
  2. ^ Walker KF, et al. The dangers of the day of birth. 2014-05. Accessed 2016-07-30.
  3. ^ Howard, R. A. (1980). J. Richard; C. Schwing; Walter A. Albers (eds.). On making life and death decisions. Societal Risk Assessment: How Safe Is Safe Enough? General Motors Research Laboratories. New York: Plenum Press. ISBN 0306405547.
  4. ^ a b "Deaths Registered in England and Wales (Series DR), 2012" (PDF). Office for National Statistics. 22 October 2013. Retrieved 3 June 2014.
  5. ^ "Leading causes of death, by sex (Both sexes)". Statistics Canada. Retrieved 14 August 2015.
  6. ^ a b c SL Murphy; J Xu & KD Kochanek (8 May 2013). "Deaths: Final Data for 2010" (PDF). US: Centers for Disease Control and Prevention. Retrieved 3 June 2014.
  7. ^ "Suicides in the United Kingdom, 2012 Registrations". Office for National Statistics. 18 February 2014. Retrieved 11 June 2014.
  8. ^ KF Walker; AL Cohen; SH Walker; KM Allen; DL Baines; JG Thornton (13 February 2014). "The dangers of the day of birth". British Journal of Obstetrics & Gynaecology. 121 (6): 714–8. doi:10.1111/1471-0528.12544. PMID 24521517.
  9. ^ "Life Tables". cdc.gov. US: Centers for Disease Control and Prevention. 2013. Retrieved 24 November 2013.
  10. ^ Blastland, Michael; Spiegelhalter, David (2014). The Norm Chronicles: Stories and Numbers About Danger and Death (1 ed.). Basic Books. p. 14. ISBN 9780465085705.
  11. ^ Office for National Statistics (13 February 2014). "Crime Statistics, Focus on Violent Crime and Sexual Offences, 2012/13 – ONS". Retrieved 12 June 2014.
  12. ^ "Leading causes of death, total population, by age group and sex, Canada". Statistics Canada.
  13. ^ Federal Bureau of Investigation. "Crime in the United States, 2012: Table 16". FBI. Retrieved 12 June 2014.
  14. ^ a b British Sub-Aqua Club. "UK Diving Fatalities Review". Archived from the original on 28 July 2014. Retrieved 12 June 2014.
  15. ^ Divers Alert Network (DAN). "Fatalities_Proceedings.pdf" (PDF). Retrieved 12 June 2014.
  16. ^ Ski-injury.com. "Ski Injury". Archived from the original on 28 May 2014. Retrieved 12 June 2014.
  17. ^ United States Parachute Association. "Skydiving Safety". Retrieved 10 April 2018.
  18. ^ British Parachute Association (2012). "How Safe". Retrieved 12 June 2014.
  19. ^ Kipps, Courtney; Sanjay Sharma; Dan Tunstall Pedoe (1 January 2011). "The incidence of exercise-associated hyponatraemia in the London marathon". British Journal of Sports Medicine. 45 (1): 14–19. doi:10.1136/bjsm.2009.059535. PMID 19622524. Retrieved 12 June 2014.
  20. ^ Soreide, Kjetil; Christian Lycke Ellingsen; Vibeke Knutson (May 2007). "How Dangerous is BASE Jumping? An Analysis of Adverse Events in 20,850 Jumps From the Kjerag Massif, Norway". The Journal of Trauma: Injury, Infection, and Critical Care. 62 (5): 1113–1117. doi:10.1097/01.ta.0000239815.73858.88. ISSN 0022-5282. PMID 17495709. Retrieved 12 June 2014.
  21. ^ "Tod am Matterhorn" (PDF; 2,31 MB). Beobachter (in German).
  22. ^ "The World's Tallest Mountain". Earth Observatory. NASA. 2 January 2014.
  23. ^ a b c d Spiegelhalter, David (10 February 2009). "230 miles in a car equates to one micromort: The agony and Ecstasy of risk-taking". The Times. London. Retrieved 19 April 2009.
  24. ^ a b c "Understanding Uncertainty". Understanding Uncertainty. Retrieved 24 August 2013.
  25. ^ a b c d e f g h i j k * Howard, Ron Risky Decisions (Slide show), Stanford University
  26. ^ "The Odds of Airborne Terror". 27 December 2009. Retrieved 17 November 2013.
  27. ^ Advisory Council on the Misuse of Drugs. MDMA ('ecstasy'): a review of its harms and classification under the Misuse of Drugs Act 1971. London: UK Home Office, 2009: p 18. http://www.homeoffice.gov.uk/publications/agencies-public-bodies/acmd1/mdma-report
  28. ^ Blastland, Michael; Spiegelhalter, David (2014). The Norm Chronicles: Stories and Numbers About Danger and Death (1 ed.). Basic Books. p. 8. ISBN 9780465085705.
  29. ^ Walker, K. F.; Cohen, A. L.; Walker, S. H.; Allen, K. M.; Baines, D. L.; Thornton, J. G. (May 2014). "The dangers of the day of birth". BJOG: An International Journal of Obstetrics and Gynaecology. 121 (6): 714–718. doi:10.1111/1471-0528.12544. ISSN 1471-0528. PMID 24521517.
  30. ^ a b Spiegelhalter, David; Blastland, Michael (30 May 2013). The Norm Chronicles: Stories and numbers about danger (Main ed.). London: Profile Books. ISBN 9781846686207.
  31. ^ Howard, R. A. (1989). "Microrisks for Medical Decision Analysis". International Journal of Technology Assessment in Health Care. 5 (3): 357–370. doi:10.1017/S026646230000742X. PMID 10295520.
  32. ^ a b Russell, Stuart; Norvig, Peter (2009). Artificial Intelligence (3rd ed.). Prentice Hall. p. 616. ISBN 978-0-13-604259-4.
  33. ^ Department for Transport GMH, United Kingdom, "TAG Unit 3.4: The Safety Objective", Transport Analysis Guidance—WebTAG http://www.dft.gov.uk/webtag/documents/expert/unit3.4.1.php
  34. ^ US Department of Transportation, "Treatment of the Economic Value of a Statistical Life in Departmental Analyses—2011 Interim Adjustment", 2011, http://www.dot.gov/policy/transportation-policy/treatment-economic-value-statistical-life
  35. ^ "Radiation dose issues and risk" (PDF). European Society of Radiology. Archived from the original (PDF) on 19 February 2014. Retrieved 18 November 2013.

Further reading

Algor mortis

Algor mortis (Latin: algor—coldness; mortis—of death), the second stage of death, is the change in body temperature post mortem, until the ambient temperature is matched. This is generally a steady decline, although if the ambient temperature is above the body temperature (such as in a hot desert), the change in temperature will be positive, as the (relatively) cooler body acclimates to the warmer environment. External factors can have a significant influence.

The term was first used by Dowler in 1849. The first published measurements of the intervals of temperature after death were done by Dr John Davey in 1839.

Dead on arrival

Dead on arrival (DOA), also dead in the field and brought in dead (BID), indicates that a patient was found to be already clinically dead upon the arrival of professional medical assistance, often in the form of first responders such as emergency medical technicians, paramedics, or police.

In some jurisdictions, first responders must consult verbally with a physician before officially pronouncing a patient deceased, but once cardiopulmonary resuscitation is initiated, it must be continued until a physician can pronounce the patient dead.

Death messenger

Death messengers, in former times, were those who were dispatched to spread the news that an inhabitant of their city or village had died. They were to wear unadorned black and go door to door with the message, "You are asked to attend the funeral of the departed __________ at (time, date, and place)." This was all they were allowed to say, and were to move on to the next house immediately after uttering the announcement. This tradition persisted in some areas to as late as the mid-19th century.

Death rattle

Terminal respiratory secretions (or simply terminal secretions), known colloquially as a death rattle, are sounds often produced by someone who is near death as a result of fluids such as saliva and bronchial secretions accumulating in the throat and upper chest. Those who are dying may lose their ability to swallow and may have increased production of bronchial secretions, resulting in such an accumulation. Usually, two or three days earlier, the symptoms of approaching death can be observed as saliva accumulates in the throat, making it very difficult to take even a spoonful of water. Related symptoms can include shortness of breath and rapid chest movement. While death rattle is a strong indication that someone is near death, it can also be produced by other problems that cause interference with the swallowing reflex, such as brain injuries.It is sometimes misinterpreted as the sound of the person choking to death, or alternatively, that they are gargling.

Dignified death

Dignified death is a somewhat elusive concept often related to suicide. One factor that has been cited as a core component of dignified death is maintaining a sense of control. Another view is that a truly dignified death is an extension of a dignified life. There is some concern that assisted suicide does not guarantee a dignified death, since some patients may experience complications such as nausea and vomiting. There is some concern that age discrimination denies the elderly a dignified death.

Fan death

Fan death is a well-known superstition in Korean culture, where it is thought that running an electric fan in a closed room with unopened or no windows will prove fatal. Despite no concrete evidence to support the concept, belief in fan death persists to this day in Korea, and also to a lesser extent in Japan.

Lazarus sign

The Lazarus sign or Lazarus reflex is a reflex movement in brain-dead or brainstem failure patients, which causes them to briefly raise their arms and drop them crossed on their chests (in a position similar to some Egyptian mummies). The phenomenon is named after the Biblical figure Lazarus of Bethany, whom Jesus Christ raised from the dead in the Gospel of John.

List of unusual units of measurement

An unusual unit of measurement is a unit of measurement that does not form part of a coherent system of measurement; especially in that its exact quantity may not be well known or that it may be an inconvenient multiple or fraction of base units in such systems.

This definition is not exact since it includes units such as the week or the light-year are quite "usual" in the sense that they are often used but which can be "unusual" if taken out of their common context, as demonstrated by the Furlong/Firkin/Fortnight (FFF) system of units.

Many of the unusual units of measurements listed here are colloquial measurements, units devised to compare a measurement to common and familiar objects.


Megadeath (or megacorpse) is one million human deaths, usually caused by a nuclear explosion. The term was used by scientists and thinkers who strategized likely outcomes of all-out nuclear warfare.


A microlife is a unit of risk representing half an hour change of life expectancy.Introduced by David Spiegelhalter and Alejandro Leiva, microlives are intended as a simple way of communicating the impact of a lifestyle or environmental risk factor, based on the associated daily proportional effect on expected length of life. Similar to the micromort (one in a million probability of death) the microlife is intended for "rough but fair comparisons between the sizes of chronic risks". This is to avoid the biasing effects of describing risks in relative hazard ratios, converting them into somewhat tangible units. Similarly they bring long-term future risks into the here-and-now as a gain or loss of time.

"A daily loss or gain of 30 minutes can be termed a microlife, because 1 000 000 half hours (57 years) roughly corresponds to a lifetime of adult exposure."The microlife exploits that for small hazard ratios the change in life expectancy is roughly linear. They are by necessity rough estimates, based on averages over population and lifetime. Effects of individual variability, short-term or changing habits, and causal factors are not taken into account.

Micromort (software)

MICROMORT is a computer program (by Heisey and Fuller, 1985) used to estimate mortality rates, commonly used in ecological studies.

Mortality rate

Mortality rate, or death rate, is a measure of the number of deaths (in general, or due to a specific cause) in a particular population, scaled to the size of that population, per unit of time. Mortality rate is typically expressed in units of deaths per 1,000 individuals per year; thus, a mortality rate of 9.5 (out of 1,000) in a population of 1,000 would mean 9.5 deaths per year in that entire population, or 0.95% out of the total. It is distinct from "morbidity", which is either the prevalence or incidence of a disease, and also from the incidence rate (the number of newly appearing cases of the disease per unit of time).

In the generic form, mortality rates are calculated as:

where d represents the deaths occurring within a given time period, p represents the size of the population in which the deaths occur and is a conversion factor from fraction to some other unit (such as multiplying by to get mortality rate per 1,000 individuals).


A necronym (from the Greek words νεκρός, nekros, "dead" and ὄνομα ónoma, "name") is a reference to, or name of, a person who has died. Many cultures have taboos and traditions associated with referring to such a person. These vary from the extreme of never again speaking the person's real name, often using some circumlocution instead, to the opposite extreme of commemorating it incessantly by naming other things or people after the deceased.

For instance, in some cultures it is common for a newborn child to receive the name (a necronym) of a relative who has recently died, while in others to reuse such a name would be considered extremely inappropriate or even forbidden. While this varies from culture to culture, the use of necronyms is quite common.


Necrophobia is a specific phobia which is the irrational fear of dead things (e.g., corpses) as well as things associated with death (e.g., coffins, tombstones, funerals, cemeteries). With all types of emotions, obsession with death becomes evident in both fascination and objectification. In a cultural sense, necrophobia may also be used to mean a fear of the dead by a cultural group, e.g., a belief that the spirits of the dead will return to haunt the living.Symptoms include: shortness of breath, rapid breathing, irregular heartbeat, sweating, dry mouth and shaking, feeling sick and uneasy, psychological instability, and an altogether feeling of dread and trepidation. The sufferer may feel this phobia all the time. The sufferer may also experience this sensation when something triggers the fear, like a close encounter with a dead animal or the funeral of a loved one or friend. The fear may have developed when a person witnessed a death, or was forced to attend a funeral as a child. Some people experience this after viewing frightening media.The fear can manifest itself as a serious condition. Treatment options include medication and therapy.The word necrophobia is derived from the Greek nekros (νεκρός) for "corpse" and the Greek phobos (φόβος) for "fear".


An obituary (obit for short) is a news article that reports the recent death of a person, typically along with an account of the person's life and information about the upcoming funeral. In large cities and larger newspapers, obituaries are written only for people considered significant. In local newspapers, an obituary may be published for any local resident upon death. A necrology is a register or list of records of the deaths of people related to a particular organization, group or field, which may only contain the sparsest details, or small obituaries. Historical necrologies can be important sources of information.

Two types of paid advertisements are related to obituaries. One, known as a death notice, omits most biographical details and may be a legally required public notice under some circumstances. The other type, a paid memorial advertisement, is usually written by family members or friends, perhaps with assistance from a funeral home. Both types of paid advertisements are usually run as classified advertisements.

Pallor mortis

Pallor mortis (Latin: pallor "paleness", mortis "of death"), the first stage of death, is an after-death paleness that occurs in those with light/white skin.

Post-mortem interval

Post-mortem interval (PMI) is the time that has elapsed since a person has died. If the time in question is not known, a number of medical/scientific techniques are used to determine it. This also can refer to the stage of decomposition of the body.

Rigor mortis

Rigor mortis (Latin: rigor "stiffness", mortis "of death"), or postmortem rigidity, is the third stage of death. It is one of the recognizable signs of death, characterized by stiffening of the limbs of the corpse caused by chemical changes in the muscles postmortem. In humans, rigor mortis can occur as soon as four hours after death.


Skeletonization refers to the final stage of decomposition, during which the last vestiges of the soft tissues of a corpse or carcass have decayed or dried to the point that the skeleton is exposed. By the end of the skeletonization process, all soft tissue will have been eliminated, leaving only disarticulated bones. In a temperate climate, it usually requires three weeks to several years for a body to completely decompose into a skeleton, depending on factors such as temperature, humidity, presence of insects, and submergence in a substrate such as water. In tropical climates, skeletonization can occur in weeks, while in tundra areas, skeletonization may take years or may never occur, if subzero temperatures persist. Natural embalming processes in peat bogs or salt deserts can delay the process indefinitely, sometimes resulting in natural mummification.The rate of skeletonization and the present condition of a corpse or carcass can be used to determine the time of death.After skeletonization, if scavenging animals do not destroy or remove the bones, acids in many fertile soils take about 20 years to completely dissolve the skeleton of mid- to large-size mammals, such as humans, leaving no trace of the organism. In neutral-pH soil or sand, the skeleton can persist for hundreds of years before it finally disintegrates. Alternately, especially in very fine, dry, salty, anoxic, or mildly alkaline soils, bones may undergo fossilization, converting into minerals that may persist indefinitely.

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