Korean Fan Death

by Brian Dunning
December 6, 2011

Today we're going to point the skeptical eye at a traditional belief from Korea, one at which many Westerners merely scoff. Many Koreans believe that sleeping in a room with an electric fan running is potentially lethal, even to the point that many Korean doctors and safety agencies formally warn against doing so. Scientists outside of Korea, however, easily dismiss the deaths as misdiagnoses of other conditions, and handily debunk the proposed mechanisms for the danger as implausible. But some Koreans have countered that there must be some explanation unique to Korea or Koreans: something to do with physiology, geography, or even their particular electric fans. Could Koreans be right that there is something more to this urban legend than mere tradition and confirmation bias?

Korean fan death isn't very old; not even going back as far as the use of electric fans in the country. The first electricity was installed at Gyeongbok Palace in 1887, just a few years after Schuyler Wheeler made the first two-bladed electric fans commercially available. By 1900, companies like Toshiba were manufacturing and selling electric fans throughout Asia. Despite nearly a century of history of usage without incident, in the 1970s the Korean media suddenly began reporting cases of fan death. They happened in the summer, in a closed room, and usually involved an elderly person sleeping alone, with an electric fan running in the room. In the morning, the victim would be found dead, with the only evident cause of death being the electric fan still sitting there, blowing its supposedly lethal breeze.

The situation today is that government safety agencies warn that fans must be used safely. The Korea Consumer Protection Board analyzed reports of heat-related injuries during the summer months for the three years prior to 2006, and made recommendations to address the five most often recurring dangers, with the first on the list being that doors should be left open when using electric fans or air conditioning.

If bodies are exposed to electric fans or air conditioners for too long, it causes bodies to lose water and hypothermia. If directly in contact with a fan, this could lead to death from increase of carbon dioxide saturation concentration and decrease of oxygen concentration. The risks are higher for the elderly and patients with respiratory problems.

From 2003-2005, 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.

Other government agencies give similar guidelines. As a result, many electric fans available in Korea today are equipped with an automatic timer feature, to make the fan turn itself off after a period of time for safety reasons. Fans from the Korean manufacturer Shinil Industrial bear a warning label that states "This product may cause suffocation or hypothermia". Such fans have a little warning sticker, a red circle with a yellow center, showing a body lying beside an electric fan.

The obvious questions to ask are how and why does this happen? But the important rule of thumb we learn to remember here is that the first question we should ask when investigating a strange phenomenon is does it actually happen at all? Obviously people do die in Korea, and some of them have fans running at the time. Whether the fan is causing the death is a question for the Korean coroners; and whether there's a plausible mechanism for such a death is a question for science. Let's take a quick look at the proposed explanations.

When we do this, we encounter our first red flag. Proposed explanations for Korean fan death are all over the map. There is no accepted scientific explanation. The most common is asphyxiation, caused by wind currents. Hypothermia is the second strongest contender, caused by the fan evaporating enough sweat off the victim's skin to wick away enough heat to kill them. But Korea's temperate climate is wet year round, especially during its summer monsoon season. The summers are hot and wet, and the winters are cold and comparatively dry. Fan death is a summer phenomenon; it's hot and wet. Are people really dying of hypothermia in such conditions? It is possible, if a stretch, if the fan's current is steady and dry enough. But fans don't dry the air or change its temperature; they merely circulate it.

Some posit really far-out explanations based on purely bad science. Some think the fan blades chop the oxygen molecules in half, rendering them useless or even poisonous; others believe that electric fans use up oxygen and produce carbon dioxide.

And, as with many urban legends, there's even a conspiracy theory that's been proposed to explain fears of fan death. When the stories first appeared in the 1970s, it was during a time when energy usage was sharply on the rise, and the Korean government thought up and spread the rumor to scare people into turning off their fans at night and saving energy. But like so many unproven conspiracy theories, this one has a pretty large hole in its logic. Energy usage during the summer is greatest during the day; and if the government was going to invent a rumor designed to reduce consumption, it would have made more sense to get people to turn something off during the day, like air conditioning or lights.

At least one Western expert has endorsed the theory that it is indeed the effect of the fan that kills. Dr. Laurence Kalkstein at the University of Miami is a climatologist and biometeorologist, studying the effects of weather on plants and animals including humans. At a conference in Korea, he explained that a fan blowing on an elderly person sleeping in a hot room would actually dehydrate the skin, causing death from respiratory distress. Even though the air blown onto the victim is as humid as a Korean monsoon, it should still carry away some amount of sweat from the skin, causing dehydration. So far as I've been able to find, Kalkstein has not examined any victims of fan death, so his suggested explanation remains unconfirmed.

However, there are doctors who have examined fan death victims. In 2007, Dr. John Linton who had autopsied several such people, told the International Herald Tribune:

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 told the Korea Times in 2006:

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.

But these dissenting opinions are in the minority. Most fan death victims examined by Korean doctors are given a cause of death of asphyxiation caused by the fan. Two professors of emergency medicine at Seoul's Samsung Medical Center agree that when a fan blows on your face, air currents develop that reduce the atmospheric pressure in front of your face by as much as 20%, causing a similar drop in oxygen availability. The victim then dies from the lack of oxygen. This is the prevailing view among Korean doctors who accept the fan death diagnosis.

The view is also wildly implausible, from any number of basic science perspectives. First, we don't observe people keeling over dead on mildly breezy days, even if they're sitting on a beach facing into the breeze for a long time. Second, we have no cases of brain damage from asphyxiation that was not quite sufficient to kill, which should be far more prevalent if this were indeed happening. Third, wind striking you in the face does not reduce the pressure at the front of your head; it increases it. Fourth, 20% is a huge pressure differential. 15 kph of wind would create around 55 grams of pressure on the average head, which is less than 1% of 1% more than normal atmospheric pressure. The Samsung doctors' 20% drop in pressure on one side of your head would require in the neighborhood of 100 kilograms of force at sea level, which would require a wind speed of at least 650 kph. So if you're using an F-18 fighter jet engine for a fan, it starts to look plausible.

So how do we properly analyze the phenomenon of Korean Fan Death? If we follow a truly skeptical process, what do we come up with? We've looked at the data and found that there are, indeed, plenty of people who have been found dead near a fan and had their deaths classified as fan death. But we also have good reasons to suspect that those causes of death were misdiagnosed: there are simply no plausible mechanisms for the breeze from a fan to be lethally dangerous. There was no significant difference in fan design introduced around the time the deaths began to be reported, and no differences between Korean fans and those in the rest of the world. There is nothing unique to Korea's geography (that we know of) that would explain why such a thing happens only there, and there aren't really any comparable cases of unique geography elsewhere in the world making certain technologies dangerous. Koreans outside of Korea don't seem to have any trouble with fans, and there is no known difference in Korean anatomy that would make them especially susceptible. Truly, all the possible factors that would make fan death a uniquely Korean phenomenon fall apart under scrutiny.

However, there's at least one remaining possibility that can explain what's being reported, and it doesn't require any new discoveries about anatomy or fans, or any special conditions. The simple fact is that we absolutely expect to see a correlation between summer deaths and fan usage. When it's hot and muggy in the summer, people are going to be running their fans; and when high-risk elderly people happen to die from whatever heat-related cause, it's perfectly likely that a running fan will be found nearby. The perception of a causal relationship between the two will be reinforced every time it's confirmed by another such body being found. This simple confusion between correlation and causation adequately explains all twenty diagnoses investigated by the Korea Consumer Protection Board, and it explains the convictions of the doctors, the fan manufacturers, and the safety boards.

So we never really get past our original question: Whether fan death has ever actually happened. It may have, most likely via hypothermia, but it would have to be in a colder, drier climate, and would be evenly distributed throughout such regions of the world. But so far as the existence of a specific Korean fan death phenomenon, the skeptical mind concludes no, there is no good evidence for such a thing's existence.

By Brian Dunning
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