Micromort

A micromort (from micro- and mortality) is a unit of risk defined as a one-in-a-million chance of death. Micromorts are usually assigned per event, or per unit of time a person is exposed to something. Micromorts can be used to measure the 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 mortality from an event, or the health impacts of an event. The micromort concept was introduced by Ronald A. Howard who pioneered the modern practice of decision analysis.

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 rough estimate.

A related and somewhat opposing unit is the microlife, which measures statistical improvements to life expectancy from an activity—one example being regular aerobic exercise.

Baseline Death from Context Time period N deaths N population Micromorts per unit of exposure ReferenceAll causesEngland and Wales2012499,33156,567,00024 per day 8,800 per yearONS Deaths Table 5.Canada2011242,07433,476,68820 per day 7,200 per yearStatistics CanadaUS20102,468,435308,500,00022 per day 8,000 per yearCDC Deaths Table 18.Non-natural causeEngland and Wales201217,46256,567,0000.8 per day 300 per yearONS Deaths Table 5.19.US2010180,000308,500,0001.6 per day 580 per yearCDC Deaths Table 18Non-natural cause (excluding suicide)England and Wales201212,95556,567,0000.6 per day 230 per yearONS SuicidesUS2010142,000308,500,0001.3 per day 460 per yearCDC Deaths Table 18.All causes – first day of lifeEngland and Wales2007430 per first day of lifeWalker, 2014US201316.7 per day 6100 per yearCDC Life Tables Blastland & Spiegelhalter, 2014Murder/homicideEngland and Wales2012/1355156,567,00010 per yearONS CrimeHomicideCanada201152733,476,68815 per yearStatistics CanadaMurder and non-negligent manslaughterUS201214,173292,000,00048 per yearFBI Table 16

Leisure and sport Death from Context Time period N deaths N exposure Micromorts per unit of exposure ReferenceScuba divingUK: BSAC members1998–20097514,000,000 dives5 per diveBSACUK: non-BSAC1998–200912212,000,000 dives10 per diveBSACUS – insured members of DAN2000–20061871,131,367 members164 per year as member of DAN 5 per diveDAN p75ParaglidingTurkey2004–201118242,355 flights74 per launchCanbek 2015SkiingUS2008/93957,000,000 days skiing0.7 per daySki-injury.comSkydivingUS2000–201641348,600,000 jumps8 per jumpUSPAUK1994–2013414,864,268 jumps8 per jumpBPABASE jumpingKjerag Massif, Norway1995–2005920,850 jumps430 per jumpSoreide 2007MountaineeringAscent to Matterhorn1981–2011213about 75,000 ascents (about 2500 per year)about 2,840 per ascent attemptBachmann 2012Ascent to Mt. Everest1922–20122235,656 successful ascents37,932 per successful ascentNASA 2013

Travel The distance associated with a gain of one micromort, by mode of transportation: Travelling 8.8 miles (14 km) by motorcycle (collision, UK) Travelling 30 miles (50 km) by walking (collision, UK) Travelling 44 miles (71 km) by bicycle (collision, UK) Travelling 370 miles (600 km) by car (collision, UK) Travelling 1,000 miles (1,600 km) by jet airplane (collision) Travelling 6,000 miles (10,000 km) by train (collision)

Other Increase in death risk for other activities on a per-event basis: Hang gliding – 8 micromorts per flight Ecstasy (MDMA) – 0.5 micromorts per tablet, rising to 13 if using other drugs Giving birth (vaginal) – 120 micromorts Giving birth (caesarean) – 170 micromorts AstraZeneca vaccination against COVID-19 – 2.9 micromorts COVID-19 infection at age 10, in December 2020 – 20 micromorts COVID-19 infection at age 25, in December 2020 – 100 micromorts COVID-19 infection at age 55, in December 2020 – 4,000 micromorts COVID-19 infection at age 65, in December 2020 – 14,000 micromorts COVID-19 infection at age 75, in December 2020 – 46,000 micromorts COVID-19 infection at age 85, in December 2020 – 150,000 micromorts Text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License .

Value of a micromort Willingness to pay An application of micromorts is measuring the value that humans place on risk. For example, a person can consider the amount of money they would be willing to pay to avoid a one-in-a-million chance of death (or conversely, the amount of money they would receive to accept a one-in-a-million chance of death). When offered this situation, people claim a high number. However, when looking at their day-to-day actions (e.g., how much they are willing to pay for safety features on cars), a typical value for a micromort is around $50 (in 2009). This is not to say the $50 valuation should be taken to mean that a human life (1 million micromorts) is valued at $50,000,000. Rather, people are less inclined to spend money after a certain point to increase their safety. This means that analyzing risk using the micromort is more useful when using small risks, not necessarily large ones.

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 is £1 million GBP in 1997 value (equivalent to £ million in ). 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. The US Department of Transportation uses a VSL of US$6.2 million, pricing a micromort at US$6.20.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

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, for example, an additional one micromort from: Drinking 0.5 liter of wine (cirrhosis of the liver)* Howard, Ron (Slide show), Stanford University Smoking 1.4 cigarettes (cancer, heart disease) Spending 1 hour in a coal mine (black lung disease) Spending 3 hours in a coal mine (accident) Living 2 days in New York or Boston in 1979 (air pollution) Living 2 months with a smoker (cancer, heart disease) Drinking Miami water for 1 year (cancer from chloroform) Eating 100 charcoal-broiled steaks (cancer from benzopyrene) Traveling 6000 miles (10,000 km) by jet (cancer due to increased background radiation)

Chronic risks are typically measured in terms of individual life expectancy, rather than death rates. Therefore, chronic risks are better measured with a related unit, the microlife.

Micromort

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