Fan death is a South Korean 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.
There is nevertheless some research to indicate that the use of an electric fan can cause or contribute to hyperthermia, in rare conditions.
The following was stated in a press release from July 2005:
Beware of Summer Hazards!
The Korea Consumer Protection Board (KCPB) issued a consumer safety alert after analyzing injury data related to summer accidents collected for the past three years through its Consumer Injury Surveillance System (CISS).
The top five recurring accidents are ▲ asphyxiation from electric fans and air conditioners ▲ children’s asphyxiation inside cars ▲ explosions inside cars ▲ air conditioner explosions and ▲ sanitary accidents at home.
■ Doors should be left open when sleeping with the electric fan or air conditioner turned on
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.