In South Korea, it is commonly and incorrectly believed that sleeping in a closed room with an electric fan running can be fatal. According to the Korean government, “In some cases, a fan turned on too long can cause death from suffocation, hypothermia, or fire from overheating.” The Korea Consumer Protection Board issued a consumer safety alert recommending that electric fans be set on timers, direction changed and doors left open. Belief in fan death is common even among knowledgeable medical professionals in Korea. According to Yeon Dong-su, dean of Kwandong University’s medical school, “If it is completely sealed, then in the current of an electric fan, the temperature can drop low enough to cause a person to die of hypothermia.” Whereas an air conditioner transfers heat from the air and cools it, a fan moves air without change of temperature to increase the evaporation of sweat. Leaving a fan running in an unoccupied room will not cool it; in fact, due to energy losses from the motor and viscous dissipation, a fan will slightly heat a room.