A widely held belief states that when operated in closed rooms, electric fans cause sudden death, suffocating victims by stealing their oxygen.
Fan death is a widely held belief (and misconception) prevailing in South Korea that an electric fan left running overnight in a closed room can cause the death of those inside. Fans 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.[1]
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, none of these beliefs stands up to logical or scientific scrutiny. Examples for possible justifications of belief in fan death are as follows:
That an electric fan creates a vortex, which sucks the oxygen from the enclosed and sealed room and creates a partial vacuum inside. Indoor fans are not nearly powerful enough to change the air pressure by any significant amount. Additionally if the room is closed, the gases circulate only inside the room, not changing overall pressure with respect to the environment.
That an electric fan chops up all the air 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, far above the energy produced by a fan. Furthermore, atomic oxygen is highly reactive and would produce sharp-smelling ozone, if it was produced by some mechanism. It also ignores the nearly universal[dubious – discuss] human tendency to wake up while being suffocated in a moment of sleep. Moreover, the theory makes no justifications for how and why a person will not suffocate while 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; however, most AC powered fans use induction motors, whose brushless design eliminates any possible ozone production. Ozone can be fatal in high concentrations, but under normal conditions the gas would never build up to lethal levels.
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 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. Bernoulli's principle states that as air speed increases, air pressure decreases, meaning less air to breathe, but this effect would not be anywhere near dramatic enough to kill a person.
That fans contribute to hypothermia, or abnormally low body temperature.[2] 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. Furthermore, discomfort will always wake a person long before they succumb to hypothermia.
The fan overheats after it has been left on for too long, and ceases to cool the room, instead causing the already sweltering heat to increase uncontrollably until the person dies from it. The rational explanation is that during extreme heat waves, a number of people are going to succumb to it (older or sick people), and the existence of a running fan in the room they have died in is merely circumstantial.
That fans contribute to prolonged asphyxiation due to environmental oxygen displacement or carbon dioxide intoxication.[2][3][4][5] In the process of human respiration, inhaled fresh air is exhaled with a lower concentration of oxygen gas (O2), and higher concentration of carbon dioxide gas (CO2), causing a gradual reduction of O2 and buildup of CO2 in a completely unventilated room.[6] Other indoor sources of carbon dioxide include burning fossil fuels, such as a gas-fueled water heater, and seepage through foundations in areas of high CO2 soil content.[7] Carbon dioxide is a colorless, odorless gas, and because it weighs 1.5 times more than normal air,[8] it tends to concentrate toward the floor,[5] depending on temperature and air currents. In South Korea, some people sleep on traditional floor mats, called yos, while others prefer western-style beds, and floor vents may be absent when ondol radiant underfloor heating is employed.[9] 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."[3]
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.[1] 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 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.
Media coverage
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:
The heat wave which has encompassed Korea for about a week, has generated various heat-related accidents and deaths. At least 10 people died from the effects of electric fans which can remove oxygen from the air and lower body temperatures...
On Friday in eastern Seoul, a 16-year-old girl died from suffocation after she fell asleep in her room with an electric fan in motion. The death toll from fan-related incidents reached 10 during the past week. Medical experts say that this type of death occurs when one is exposed to electric fan breezes for long hours in a sealed area. "Excessive exposure to such a condition lowers one's temperature and hampers blood circulation. And it eventually leads to the paralysis of heart and lungs," says a medical expert.
"To prevent such an accident, one should keep the windows open and not expose oneself directly to fan air," he advised.
Gord Giesbrecht, a professor of thermophysiology at the University of Manitoba,[10] is a leading expert on hypothermia:
It's hard to imagine death by fan, because to die of hypothermia, one's body temperature would have to get down to 28 [°C], drop by 10 degrees [Celsius] overnight. We've got people lying in snowbanks overnight here in Winnipeg and they survive. Maybe if someone was elderly and they were sitting there for three days in a sealed room with an electric fan turned on. Someone is not going to die from hypothermia because their body temperature drops two or three degrees overnight; it would have to drop eight to ten degrees." In addition, "the only way to verify whether someone had really died of hypothermia during the night would be to take a core body temperature the following morning. Waiting three days while the body was in the morgue wouldn't work because the corpse's temperature can drop during that time.[2]
Dr. John Linton at Yonsei's Severance Hospital, who attended medical school at Yonsei University, is licensed to practice medicine in South Korea:[2]
There are several things that could be causing the fan deaths, things like pulmonary embolisms, cerebrovascular accidents or arrhythmia. There is little scientific evidence to support that a fan alone can kill you if you are using it in a sealed room. Although it is a common belief among Koreans, there are other explainable reasons for why these deaths are happening.
Dr. Lee Yoon-song is a professor at Seoul National University'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:
When someone's body temperature drops below 35 degrees, they do start to lose judgment ability. So if someone was hiking and later found dead, that could be part of the reason. But we can't really apply this to fan accidents. I found most of the victims already had some sort of disease like heart problems or serious alcoholism. So hypothermia is not the main reason for death, but it may contribute.
He blames the Korean media for the persistence of the urban legend:
Korean reporters are constantly writing inaccurate articles about death by fan, describing these deaths as being caused by the fan. That's why it seems that fan deaths only happen in Korea, when in reality these types of deaths are quite rare. They should have reported the victim's original defects such as heart or lung disease, which are the main cause of death in these cases.
Dr. Laurence S. Kalkstein, Research Professor of Geography and Regional Studies at Miami University, however, has suggested that seniors may die from heart attack or stroke caused by the use of fans in an enclosed environment. JoongAng Ilbo quoted him who said:
If a fan is run inside an enclosed room where the indoor temperature is high, the heat is concentrated on the person, so the body temperature actually rises. As fan air blows on exposed skin, the body becomes dehydrated, resulting in a heart attack or stroke and death from respiration difficulties.
