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An urban legend states that when operated in closed rooms, electric fans cause sudden death, suffocating victims by stealing their oxygen.
Fan death is a South Koreanmarker urban legend which states that an electric fan, if left running overnight in a closed room, can cause the death of those inside (by suffocation, poisoning, or hypothermia). Fans manufactured and sold in Korea are equipped with a timer switch that turns them off after a set number of minutes, which users are frequently urged to set when going to sleep with a fan on.


The specifics behind belief in the myth of fan-death often offer several explanations for the precise mechanism by which the fan kills. However, as explained below, these beliefs do not stand up to logical and scientific scrutiny. Examples for possible justifications of belief in fan death are as follows:
  • That the South Korean government introduced the idea as a means to reduce energy use.

  • That an electric fan creates a vortex, which sucks the oxygen from the enclosed and sealed room and creates a partial vacuum inside. This explanation violates the principle of conservation of matter, as indoor fans are not nearly powerful enough to change the air pressure by any significant amount.

  • That an electric fan chops up all the oxygen particles in the air leaving none to breathe. This explanation violates mass conservation and well-known properties of molecules and gases, particularly that known breakdown energy of oxygen molecules lies in the ultraviolet range. It also ignores the nearly universal human tendency to wake up whilst being suffocated in a moment of sleep. Moreover, the theory makes no justifications for how and why a person will not suffocate whilst awake in a room which contains an operating fan.

  • The fan uses up the oxygen in the room and creates fatal levels of carbon dioxide. An electric motor does not function by combustion; unlike a candle, the electric motor consumes energy supplied by the electricity, not from a fuel. The fan motor's commutator does produce a small amount of ozone during normal operation. Ozone can be fatal in high concentrations but any normal room would never allow the gas to build up to lethal levels.

  • That if the fan is put directly in front of the face of the sleeping person, it will suck all the air away, preventing one from breathing. This explanation ignores both the fact that a fan attracts as much air to a given spot as it is removing from it, and the fact that most people point a fan towards themselves when using one, which causes air to move past the face but does not change the amount of air present. Fan death is frequently cited when police detectives are unable to determine cause of death.

  • That fans contribute to hypothermia, or abnormally low body temperature. As the metabolism slows down at night, one becomes more sensitive to temperature, and thus supposedly more prone to hypothermia. If the fan is left on all night in a sealed and enclosed room, believers in fan death suppose that it will lower the temperature of the room to the point that it can cause hypothermia. Empirical measurements will show, however, that the temperature in the room does not fall, at least not due to the fan; if at all, it should rise slightly because of friction and the heat output of the fan motor, but even this is generally not significant. Fans actually make one cooler by increasing the convection around a person's body so that heat flows from them to the air more easily, and by the latent heat of vaporization as perspiration evaporates from the body. However, there is no scientific study which indicates that this effect would be sufficient to cause hypothermia unless the temperature were already very low.

Electric fans sold in Korea are equipped with a "timer knob" switch, which turns them off after a set number of minutes: perceived as a life-saving function, particularly essential for bed-time use.

  • That fans contribute to hyperthermia, commonly known as heatstroke. The U.S. Environmental Protection Agency warns that during excessive heat event, people should not "use a portable electric fan in a closed room without windows or doors open to the outside." The EPA's position is based on the fact that although a fan can decrease the perceived room temperature and convection improves the ability of the human body to lose heat by sweating, a fan alone will not prevent hyperthermia brought on by hot weather, not that a fan will exacerbate hyperthermia by producing heat.

  • That fans contribute to prolonged asphyxiation due to environmental oxygen displacement or carbon dioxide intoxication.ondol radiant underfloor heating is employed. According to The Straight Dope website run by the Chicago Reader newspaper, asphyxiation is an unlikely cause of fan death because "few rooms are totally sealed, and the fan would tend to keep CO2 and other gases well mixed."

South Korean government position

The Korea Consumer Protection Board (KCPB), a South Korean government-funded public agency, issued a consumer safety alert in 2006 warning that "asphyxiation from electric fans and air conditioners" was among South Korea's five most common seasonal summer accidents or injuries, according to data they collected. Also included among the five hazards were air conditioner explosions and sanitation issues, including food poisoning and opportunistic pathogens harbored in air conditioners. The KCPB actually published the following:

If bodies are exposed to electric fans or air conditioners for too long, it causes [the] bodies to lose water and [causes] hypothermia. If directly in contact with [air current from] a fan, this could lead to death from [an] increase of carbon dioxide saturation concentration [sic] and decrease of oxygen concentration. The risks are higher for the elderly and patients with respiratory problems. From 2003 [to] 2005, a total of 20 cases were reported through the CISS involving asphyxiations caused by leaving electric fans and air conditioners on while sleeping. To prevent asphyxiation, timers should be set, wind direction should be rotated and doors should be left open.

Fan-related hyperthermia research

Whenever conditions are present which cause heat exhaustion or heat stroke, it is important to realize that a fan does not lower air temperature. It is unsafe to rely on a fan to relieve heat stroke. In fact, technically, fans actually raise air temperature, since their motors produce heat, though by extremely small amounts that would be far from showing up on thermometers. In most conditions fan use will reduce body temperature through evaporation, but it does so at the cost of body fluids, which can increase health risk. There are cases of extreme heat and humidity where a fan can actually push heat onto the human body.

Research suggests that fan use may be a contributing factor in heat-related deaths such as fatal cases of hyperthermia. A U.S. Centers for Disease Control and Prevention study published in the Journal of the American Medical Association advises that "although the use of fans may increase comfort at temperatures less than 90°F (less than 32.2°C), fans are not protective against heatstroke when temperatures reach greater than or equal to 90°F (greater than or equal to 32.2°C) and humidity exceeds 35%," and provides a similar but simpler warning to the public on their website. These temperature and humidity conditions are consistent with a death cited in an earlier article critical of fan death, which suggested that fan use was irrelevant.

Texts on industrial hygiene and ventilation will describe conditions when the use of a fan will increase a worker's heat load. Those conditions include very high temperatures found in foundries and similar industries like heat treating metals. Similar problems occur with high heat and high humidity.

A 2007 meta-analysis of studies on heat wave-related deaths explains that "a fan induces air movement that increases evaporation and lowers skin temperature, but in warm environments increased wind speeds of hot air can actually raise the skin temperature and thus produce opposite results by increasing core body temperature." The study concludes that definitive recommendations on fan use require further study.

An analysis of risk factors contributing to 700 "excess deaths" during a 1995 Chicago, Illinois, heat wave found no evidence that fans either increased or decreased mortality, but noted that "interpretation of the data on the use of fans is complicated by the need to take into account specific environmental factors (for example, whether the fan is used in a room with an open or a closed window) and the health status of individual subjects." Fear of crime was cited as a factor in people keeping windows and doors locked shut.

Media coverage

The phenomenon of fan death is accepted by many Korean medical professionals. In summer, mainstream Korean news sources regularly report on cases of fan death. A typical example is this excerpt from the July 28, 1997, edition of The Korea Herald, an English-language newspaper:

According to The Straight Dope website, when informed that the phenomenon is virtually unheard of outside of their country, "some locals claim Koreans are uniquely vulnerable due to a peculiarity either of their own physiology or of Korean fans."

Published professional opinion

Gord Giesbrecht, a professor of thermophysiology at the University of Manitobamarker in Canadamarker, is a leading expert on hypothermia:Dr. John Linton at Yonsei's Severance Hospital, who attended medical school at Yonsei Universitymarker, is licensed to practice medicine in South Korea:

Dr. Lee Yoon-song is a professor at Seoul National Universitymarker's medical school and works with the school's Institute of Scientific Investigation. He has conducted autopsies on some of the people who have been described in Korean media as having succumbed to fan death:

He blames the Korean media for the persistence of the urban legend:

See also


  1. Surridge, Grant. (2004-09-22). "Newspapers fan belief in urban myth." JoongAng Daily, via and Retrieved on 2007-08-30.
  2. Perrin A., J. Samenow, J. Ferrel, et al. June 2006. Excessive Heat Events Guidebook. United States Environmental Protection Agency, publication EPA 430-B-06-005. Retrieved on 2007-09-04.
  3. Watanabe, Toshifumi, and Masahiko Morita. (1998-08-31). "Asphyxia due to oxygen deficiency by gaseous substances." Forensic Science International, Volume 96, Issue 1, Pages 47-59. Retrieved on 2007-09-06.
  4. Gill, James R., Susan F. Ely, and Zhongxue Hua. (2002). "Environmental Gas Displacement: Three Accidental Deaths in the Workplace." The American Journal of Forensic Medicine and Pathology, 23(1):26 –30, 2002. Retrieved on 2007-09-06.
  5. "Concentrated Carbon Dioxide in Western Pennsylvania." The Pittsburgh Geological Society. Retrieved on 2007-09-06.
  6. (2005-11-25). "Chemical Fact Sheets: Carbon Dioxide (CO2)." Wisconsin Department of Health & Family Services. Retrieved on 2007-09-06.
  7. (April 1999). "Safety & Health Bulletin: Protecting Workers From the Acute Effects of Carbon Dioxide Fire Extinguishing Systems Introduction." DOE/EH-0196, Issue 99-1, Office of Occupational Safety and Health Policy, U.S. Department of Energy. Retrieved on 2007-09-06.
  8. "Chapter 3: Housing" Everyday Korean Life, Korea Local Authorities Foundation for International Relations (KLAFIR). Retrieved on 2007-09-06.
  9. Centers for Disease Control and Prevention. "Heat-related illnesses, deaths, and risk factors—Cincinnati and Dayton, Ohio, 1999, and United States, 1979-1997." The Journal of the American Medical Association, 2000;284(1):34-35, via Retrieved on 2007-09-03.
  10. "Tips for Preventing Heat-Related Illness." (Website). "Emergency Preparedness & Response," Centers for Disease Control and Prevention, United States Department of Health and Human Services, 2006-08-15. Retrieved on 2007-09-03.
  11. Bouchama, Abderrezak, Mohammed Dehbi, Gamal Mohamed, Franziska Matthies, Mohamed Shoukri, Bettina Menne. 2007. "Prognostic Factors in Heat Wave–Related Deaths: A Meta-analysis." Archives of Internal Medicine 2007;167:(doi:10.1001/archinte.167.20.ira70009), early release article (2007-08-13) via Retrieved on 2007-09-03.
  12. Semenza, J.C., C.H. Rubin, K.H. Falter, et al. 1996. "Heat-related deaths during the July 1995 heat wave in Chicago". New England Journal of Medicine, 1996;335(2):84-90. Retrieved on 2007-09-03.
  13. 2005-09-07. "Fall 2005 Curriculum (Archive), Learning Series Session (Sept. 21, 2005): Keep Your Head Up: A Primer on Cold Water Immersion and Near-Drowning." (Website). Smartrisk Navigator. Retrieved on 2007-09-01.

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