Putting two electric fans together can cause suffocation to death? This is something you really need to pay attention to in the summer...

In the summer of 1973, 37-year-old Korean man Lee Yun-jae was found dead in his attic. When the police arrived at the scene, they found two fans whirring less than 80 centimeters away from the body.

The attic where the crime occurred is a fully enclosed environment, with no other entrances or exits except a staircase leading to the lower floor. Was this homicide or an accident? Were there any fatal injuries?

The title of the article published in the media revealed the answer: “Man in his 30s suffocates after sleeping with fan on”[1].

The "fan-related death" incident has once again entered the public eye.

Half a century before this incident, "electric fan killings" had aroused the vigilance of the Korean people, and leaving the electric fan on all night became an unwritten "taboo."

Wikipedia’s introduction to “fan-induced death” [2] Image source: Wikipedia

01

Korean urban legend?

“Fan Disease: The Mysterious Dangers of Electric Fans That Can Be Life-threatening If Done Wrong”[3], this seemingly fantastical article was published in a Korean newspaper in 1927.

The article was the first to put forward the view that fans may cause harm: the rotation of fans creates a vacuum, which can cause people sitting nearby to have difficulty breathing due to lack of oxygen, causing symptoms such as headaches, facial nerve paralysis, and suffocation.

South Korean newspapers reported that fans can cause a range of diseases. Image source: Reference [3]

The "fans are harmful" theory thus entered the Korean social stage.

In the following years, Dong-A Ilbo published a series of articles emphasizing the impact of fans on health, and the reason changed from creating a vacuum to producing a "storm": when the wind generated by the fan hits the skin surface, the human body temperature will drop rapidly, leading to abnormal blood circulation, causing chills and discomfort.

The controversial "fan mystery" has not disappeared with the passage of time.

In 2007, the Korea Consumer Protection Association issued a notice to remind the public: To prevent suffocation, when using electric fans, you should set a timer, turn on the sweep function, and keep the door open.

However, outside of South Korea, electric fans are a great way to cool off and have never been considered a "weapon of danger." Does this unique urban legend in South Korea hide any real safety risks?

Fan manufacturers not only added warning labels to fans, but also developed an automatic power-off function to ensure user safety. Image source: simonandmartinabonus/YouTube

02

Re-enactment of scenes from film and television dramas

This "Detective Conan-style" method of death certainly cannot escape the script of film and television workers.

The TV series "Criminal Investigations 2" has a "re-enactment" of this: a confined space, a dead body lying flat, and two obvious fans that would definitely be ignored by the protagonists at the beginning.

In the TV series "Crime Scene 2", the victim died of suffocation due to sleeping with a fan on. Image source: Xigua Video

After a series of plots in which you would know even if I didn't tell you, in which the murderer looked arrogant and refused to admit that he was the murderer and even challenged the police by saying that they would never find any evidence, the screenwriter finally gave the answer: the electric fan "killed" people.

In order to restore the technique, the leading actor in the play placed two fans facing the same direction at one end of the laboratory table, and placed a barometer at the other end. When the fan's wind speed was turned to maximum, the pressure measured on the barometer gradually decreased with the passage of time.

They then gave an explanation: this phenomenon utilizes the Bernoulli principle in fluid mechanics. The pressure is low where the gas flow rate is high. In a closed environment, the body is in the low-pressure area between two fans, which eventually causes suffocation and death.

Fan simulation experiment. Image source: TV series "Crime Scene 2"

The explanation in the drama seems scientific, but it is outrageous when you think about it carefully, because the cause of death has nothing to do with the fan at all!

Ordinary household fans have very low speeds, and their impact on ambient air pressure is only about 10 to 30 kilopascals. Even the high-speed airflow generated by industrial fans can hardly reduce the air pressure to a level that would cause suffocation.

At the same time, when healthy adults feel suffocated, they will actively seek fresh air. Even when they are asleep, the body's survival instinct will prompt the brain to wake up and they will not sit still and "wait to die."

Therefore, it is impossible for the air pressure effect of the fan alone to cause suffocation.

In fact, this kind of air pressure change phenomenon is very common in our lives. For example, when you are waiting for the subway or train, your body will lean forward unconsciously when the train whizzes past in front of you. This is because the passing of the train causes the nearby air to flow rapidly, and there is an obvious pressure difference between the front and back of the body. The greater pressure behind you will push you forward.

High-speed trains will draw people towards the train body. To ensure the safety of passengers, a one-meter yellow safety line is set on the platform. Image source: CCTV News

03

The "heat wave" that cannot be underestimated

Since the "fan-related death" theory lacks scientific basis, how do we explain the "fatal" cases in the news?

In fact, along with the word "fan" in the report, there is another key point that is easily overlooked - "heat"!

In extremely hot weather, using an electric fan in a closed room may indeed cause heat stroke[4].

Dr. Kalkstein, a climatologist at the University of Miami, said fans are a "double-edged sword" when it comes to dehydration and heat stress.

If the surrounding air is too hot when a fan is used, the fan will only blow the hot air towards you and speed up the evaporation of moisture from your body.

How hot is extremely hot?

You don’t have to worry too much. A previous study[5] pointed out that, except for those living in extremely hot and dry areas, using electric fans to cool down is beneficial in the following situations.

Healthy young people: when the ambient temperature is < 39 degrees Celsius

Healthy elderly people: when the ambient temperature is < 38 degrees Celsius

Elderly people taking anticholinergic drugs: when the ambient temperature is < 37 degrees Celsius

Copyright image, no permission to reprint

In addition, experts believe that the actual cause of "fan-related death" is more likely to be that high temperatures or cold winds trigger existing chronic diseases.

When the fan becomes the protagonist of an urban legend, it becomes a "murderous demon". As a story, urban rumors always attract the public's attention. However, after peeling off the bizarre shell, we should still find out its origin and clear the name of the fan.

After all, sometimes turning on a floor fan can create a more summery atmosphere than turning on the air conditioner!

References:

[1] 선풍기켜놓고자다30대남자가질식사https://www.joongang.co.kr/article/1351736

[2] Fan death. Wikipedia. https://en.wikipedia.org/wiki/Fan_death

[3] 이른바"선풍기사망설(Fan Death)"은일제강점기에도있었다.... http://veritasest.egloos.com/2029688

[4] Excessive Heat Events Guidebook. https://www.epa.gov/heatislands/excessive-heat-events-guidebook

[5] Morris, Nathan B., et al. "Electric fan use for cooling during hot weather: a biophysical modeling study." The Lancet Planetary Health 5.6 (2021): e368-e377.

[6] Is My Electric Fan Going to Kill Me in My Sleep? https://www.theatlantic.com/health/archive/2017/05/is-this-going-to-kill-me-fan-death-korea/528243/

[7] South Korea's Quirky Notions About Electric Fans. https://www.npr.org/sections/parallels/2015/08/09/430341089/south-koreas-quirky-notions-about-electric-fans

Source: Guokr

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