If you’re anything like me, you’ve spent a lot of time lately feeling bad for your electrical fan: the poor little thing, working so hard all on its own against the bigger, stronger foes that are the heat waves sweeping the world this summer. But a new study suggests that your emotional energy (or maybe… just mine) is misplaced, because your electric fan not cool you — and actually might be the reason it’s so hot in your room, Gizmodo reported.
The study, published in the Annals of Internal Medicine, found that the amount your electric fan works depends on temperature and humidity. The research focused on studying the bodily responses of 12 young men — so, not a big sample size — to varying room temperatures and humidity conditions. Some of the participants endured two hours in intense heat with an electric fan, and others without a fan.
In hot and humid conditions, the participants reported feeling twice as comfortable with a fan than without it. Their body temperatures and cardiac stress were only slightly less with a fan than without it, however, and they sweated a whole lot more with the fan than without it. In dry heat, though, the participants’ body temperatures, cardiac stress, perspiration rate, and reported feelings of distress were all much worse with a fan than without it.
Wait, what? According to the Environmental Protection Agency (EPA), it’s weirdly not surprising that an electric fan would make dry heat feel worse. Your average body temperature is 98.6 degrees. When the heat index is higher than that (99 degrees or more), the EPA recommends turning your electric fan off.
This plot twist is because electric fans are responsible for circulating air, which results in that sweet sense of coolness. But when the air surrounding you is itself hotter than your body temperature, the fan is only hitting you with air that’s warmer than your skin. And that doesn’t sound too pleasant (because it isn’t). In case you’re wondering, the science-y reason that fans make dry heat worse but help in humid conditions is that the humidity decreases heat transfer in the air. As a result, less heat blows from the fan to your skin when it’s humid.
The study’s parameters, of course, were limited. It faces the unfortunately classic problem of using a small set of college-aged men to represent all of humanity. But it remains interesting that the men reported feeling much better in high heat and humidity with a fan, even though measurements showed they were sweating more and only had marginally lower body temperatures and cardiac stress than they had without a fan. This suggests that for some people, at least, the placebo effect of having an electrical fan might be helpful in generating feelings of dramatically increased comfort in high heat and humidity. And that placebo effect — as long as people are hydrating — might be important, since electric fans have a significantly lower carbon footprint than air conditioning. So in areas of the world where heat waves come along with high humidity, your electric fan might still be your best summer friend.