Urban Legends of the World: Death by Fan

There have been urban legends about absurd things that could kill you since the dawn of storytelling. These stories usually serve as cautionary tales told by parents to warn children of the dangers of one bogeyman or another. In South Korea, one such harbinger of death is said to be the run-of-the-mill electric fan.

You read that right, electric fans, though the fear also extends to air conditioners in some versions of the story. It is said that if a fan is left running overnight, those unfortunate enough to be in the same room will perish. Depending on the teller of the tale this death could be from suffocation, a poisoning of the air, or by inducing hypothermia. In the case of suffocation, it is said that the fan creates a vortex in a sealed room that will draw all the air out. Another, even more absurd, claim is that the blades of the fan will chop apart oxygen molecules contained in the air that is sucked into the room by the fan.

The versions of this story that warn of hypothermia claim that as you sleep your body becomes more sensitive to changes in temperature. This is true, due to the slow down of metabolism at night, the human body is more easily affected by temperature changes. There, however, have been no scientific studies that indicate that a typical fan is capable of altering the temperature by enough to induce hypothermia.

The final warning against a fans ability to create a poisoned environment is also grounded in science, yet mistaken. When a human breathes in Oxygen is absorbed from the air. When the air is exhaled it leaves the body with a higher concentration of Carbon Dioxide, due to the lowered amount of Oxygen. This theory of fan death states that the sealed environment created by the fan will eventually contain too much Carbon Dioxide and too little Oxygen, which is poisonous to humans. However, a typical room is difficult to actually seal off, even with a fan placed directly in the window. If anything, the fan should actually serve to help keep the air in the room mixed.