Deliberate urban myth?

To non-Koreans, this sounds crazy.

It appears there is a popular belief amongst Koreans, dating back to the 1920's, that sleeping in a room with a fan running and no open doors or windows can kill you.

Even when told the rest of the world doesn't believe this, the fear persists.

It's even stranger when you realise there might even be a deliberate reason for the myth, and it was actually started by the government. In the 1970's, there was an energy crisis so the fear was "made known", i.e. not directly pushed by the government in a way that could be traced to them, that people shouldn't leave fans on all night. Stories about it date much earlier than this too - even reports back to 1927 can be found.

Manufactured misconception

There are documented cases of a government putting out stories which might seem rational, but are entirely bogus, for reasons which can't be disclosed. An example is the MMDE that eating carrots is good for your eyesight, which was in fact a British cover story to cover the invention of radar in World War 2.

North Koreans in particular have a very different reason to not question authority, no matter how ludicrous the claims.

Nevertheless, some have attempted to reason with science how they could kill a person. One noble technical wordsmith posited that a fan's blades "chop up" oxygen into carbon-dioxide, which you can't breathe, so you suffocate in your sleep. Or, the fan does it's job too well and cools you so much you die from hypothermia. Another is that you die from dehydration since the fan blows away all the moisture in your body. Al of this happens whilst you sleep, so you're not aware of it happening.

The government actually released an advisory in 2005 telling citizens to leave a door or window open at night if sleeping with a fan on, and referring to the reasons just given. This probably didn't do much to debunk the myth.