Your Fans are Also Your Friends

with Marie Patino

A fan can be your best friend in the sweltering summer heat — something to mentally prepare for on the first day of spring.  But how do fans actually work?

The household fans do not lower the temperature of a room, nor do they noticeably lower your body temperature.  They simply make you feel cooler.  One of the ways your body naturally tries to cool down in hot settings is by evaporation (aka sweating).  When you sweat to lose heat, the evaporation of the sweat surrounds you with a thin layer of humidity, making hard for your sweat to continue evaporating.  A fan helps by circulating air and moving the layer of warm humidity so that you feel cooler.

*Disclaimer: Cats only sweat through their paws, but they do simulate sweating by licking their fur to cool down when the saliva evaporates.

Using fans is particularly important with the impending summer.  For example, last summer, South Korea experienced an unprecedented heat wave: Between May 18 and July 31, 28 cases of heat stroke were reported in South Korea’s North Gyeongsang Province alone.  However, some South Korean’s comfort (and possibly health) may be affected by their belief in the myth of “fan death,” which is more widely held among older generations.

The Fan Death Myth

The fan death myth is the mistaken belief that sleeping with an electric fan on overnight can cause sudden death.  One of the primary reasons people provide for this incorrect theory is the claim that household fans can cause hypothermia.  However, hypothermia happens when your body temperature drops from 98.6 degrees F to 95 degrees F, and as discussed above, fans do not actually lower your body temperature.  

Another unsubstantiated claim focuses on suffocation, which also cannot occur unless your sleeping area is specifically designed as an airtight container, which places are not.  An even wilder claim says that suffocation occurs by the fan slicing oxygen molecules and changing the chemical composition of air — this too is unsubstantiated, as a fan moving through air cannot create a chemical change.  

Fans are Friends, not Scapegoats

In fact, legend has it that many have slept with the fan on all night and survived.

A South Korean researcher was even confident enough to test this empirically on his 11-year-old daughter, checking on her every five minutes, after having difficulty finding people to take part in his experiment.  “She survived the night. Her vitals barely changed. And now, the whole family sleeps with fans blowing on them.”

Fans became scapegoats in several ways.  Most prominently, most of the early reports of fan deaths emerged in South Korea in the 1970s, when the country was struggling with higher energy prices, and as recently as 2006 the government put out a health hazard warning about electric fans.  These combine to an attempt to lower energy consumption.

Further, media reports of “fan deaths” go up in the summer, conveniently also when it’s hot and people are more likely to sleep with their fan on.  This is simply correlation, not causation.  When people it’s hot, people turn on their fans.  Sometimes, independently, they may also die.  When these events happen to occur at the same time, fans become a way to help families “save face” or the scapegoat for unexplained deaths.


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