Hi folks - Most of us by now have heard of the odd & silly superstition called Fan Death or Korean Fan Death*
If wiki is to be believed, the Korean government is having some success putting this stupidity to well-deserved rest.
That success comes just in time for fan death to becme a real thing, at least in hotter climes than Korea:
Who knew? Climate change turning odd superstitions into facts.
A glance at the article seems to suggest to me that they’re talking about times where the ambient temperature is close to or greater than the normal human body temperature. In that situation, it’s definitely reasonable to think that having more air moving over your body is counterproductive; while it might increase the rate of evaporation of your perspiration, I suspect at temperatures that high it doesn’t need much help to evaporate, and fans moving a large volume of air will just be bringing more heat your way than what leaves via increased evaporation.
Way back in elementary school, the nuns used to tell us that we shouldn’t fan ourselves (with paper fans) because it would only make us hotter. I thought it was empirically crazy. Most of these nuns were Irish. Did this Korean Fan Death myth have origins in Ireland???
That’s why we have dual direction fans chez Pipers. Insert in the sash window, and you can set them to blow air in, or blow air out.
When it’s cooler outside than in, we set it to blow air into the bedroom. When it’s hotter outside than inside, we reverse to blow out.
ETA: replying to @glowacks
I rather think that if the ambient temperature is high enough, the extra heating caused by the physical effect of fanning yourself exceeds the heat carried away by the moving air. I have always felt that way, but I thought the Korean belief was that electric fans can be deadly.
So, kind of like a convection oven?
I’ve heard this too. It sounds somewhat plausible, but I’ve wondered whether it was actually true or promulgated by people who were annoyed by kids playing with fans.
My 3rd grade (non-Catholic) teacher in the mid 1960s said the same thing, that we shouldn’t fan ourselves after coming in from recess because it would make us hotter.
Similarly, my uncle’s early 1950s edition of the World Book encyclopedia said that drinking cold water when you’re hot makes you hotter because it increases circulation.
Specifically the wet bulb temperature, which the article doesn’t bother mentioning.
This. Mexico’s Cave of Crystals runs at about 135F, with humidity around 95%. In other words, the wet-bulb temperature is pretty close to 135F, so sweating doesn’t do any good at all. In fact, since your body is much cooler than that, ambient moisture actually condenses on your skin. This is the exact opposite of sweating, and will raise your body temp pretty rapidly, not unlike steam cooking; anyone not wearing a special ice-filled cooling suit will be in rough shape after ten minutes, and a fan will only speed up the process.
I’ve cited this article before in other AGW threads, but it’s applicable here too: The emergence of heat and humidity too severe for human tolerance | Science Advances. The title describes the contents pretty well; what’s alarming is that significant chunks of highly populated areas are nudging ever-closer to those limits with no sign of slowing down.
Yeah, it was strange that they didn’t address the humidity issue, but I just thought at those temperatures that getting more convective air wouldn’t really help much seeing as you’re convecting in just as much heat as dry air. If the wet-bulb temperature is that high, increasing air flow over your skin will definitely lead to you absorbing more heat.
I understand blowing cool air in; I presume the top of the sash window is open to equalize the pressure difference created by the fan, allowing warmer air to flow out as cooler air is blown in.
But blowing air out when it’s hotter outside doesn’t make any sense. The air you are blowing out is the cooler air. Hotter air from outside will flow in to replace the cooler air flowing out. If no windows are open, the warmer air is coming in through leaks, but it is coming in: nature abhors a vacuum. If the cooler air blown out by the fan isn’t replaced from somewhere, three things may happen:
The fan stops moving air out, becuse it can’t overcome the pressure difference between inside and out.
The air pressure falls low enough that there isn’t enough oxygen to support respiration and you pass out.
The air pressure inside continues to fall untill the house implodes.
More likely, you are blowing cooler air out, and warmer air is replacing it.
I used to monitor Korean deaths. But I am no longer a fan.
I agree. The outside environment is a huge heat sink. When the outside is at a preferred temperature, you want to maximize the heat exchange to reach equilibrium as quickly as possible. When the inside is at a preferred temperature, you want to minimize the heat exchange to delay equilibrium for as long as possible.
Blowing air to/from the inside/outside increases the heat exchange. Only do it when the outside is at a preferred temperature.
This is what my HS chemistry teacher always claimed, but I disagree.
First, as long as the ambient temperature is below skin temperature: not only are you cooling by evaporating sweat, but you’re blowing off the air heated by your body and replacing it with cooler air.
Second, the motion used to fan yourself is the same motion as the royal wave - the wave that royals use when they are going to be waving a long time: it specifically uses less energy so that someone can do it for a long time without getting tired.
I wonder if my teacher and the nuns were just distracted by the movement.
Do the fans make a whooshing noise?