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Fan Death is an urban legend that originated in South Korea, but has since spread to other countries in the Far East. The belief is that an electric fan, if left running overnight in a closed room, can result in the death (by suffocation, poisoning, or hypothermia) of those inside. This belief also extends to air conditioners and the fans in cars. When the air conditioner or fan is on in a car, some people are apt to leave their car windows open a crack to avoid "fan death." 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.
There are several beliefs given as to how a fan can kill. However, as explained below, these beliefs do not stand up to logical and scientific scrutiny.
* It is believed that an electric fan creates a vortex, which sucks the oxygen from the enclosed and sealed room and creates a partial vacuum inside. In reality, the air pressure at any point in the room varies less than it does during a storm.
* It is believed that the fan uses up the oxygen in the room and creates fatal levels of carbon dioxide. There is no actual conversion of oxygen to carbon dioxide happening; unlike a candle, the electric motor in a fan does not alter the chemical composition of the air (apart from creating some ozone if the motor uses brushes, and out gassing from the materials).
* It is believed 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. However, as can be easily verified, it is possible to breathe with one's face in front of a running fan.
* It is believed that fan blades chop up air particles (i.e. oxygen molecules) so that the air is no longer breathable, thus resulting in suffocation. If this were true, regular fans could be used to create chemical reactions. However, air ionizers do turn a very small amount of oxygen into unstable ozone.
* Fans are alleged to cause hypothermia. 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 vaporisation as perspiration evaporates from the body. Furthermore, hypothermia occurs only when the body's core temperature drops below normal, and will not generally be caused simply by cooling of the skin or decrease in the body's surface temperature.
* Often, it is claimed that a combination of these factors is responsible. For example, it might be claimed that the decrease in oxygen and increase in carbon dioxide, in conjunction with some degree of hypothermia, could prove fatal to a sleeping person.
The explanation 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:
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.
When informed that the phenomenon is virtually unheard of outside of their country, some Koreans have suggested that their unique physiology renders them susceptible to fan death.[1] Such Koreans are usually at a loss to explain why Koreans born overseas, who have never heard of this phenomenon and leave fans running in closed rooms, do not suffer from fan death.
