The Little Breeze in Our Hands
In the sweltering midsummer, when the city asphalt exhales hot breaths, a small wing buzzes in our hands like a promise. It’s the handheld fan. This tiny machine’s breeze feels like a precious shield against the boiling heat.
But what if this reliable friend turns its back on us at the hottest moment? What if behind this cool breeze hides a dangerous truth threatening us? This story is a journey about how this small device that offers us momentary relief can become our greatest enemy. What handheld fans provide is not just simple coolness but perhaps the illusion of ‘being able to control everything.’
Chapter 1: The Promise of Coolness, the Magic of Science
The Magic Name: Evaporative Cooling
The principle behind how handheld fans cool us is simpler than you think. Fans don’t cool the air; they cool our bodies. The secret lies in the magic called ’evaporative cooling.’
When we’re hot, we sweat, right? The fan’s breeze quickly evaporates this sweat. As the liquid sweat turns into vapor, it takes heat away from our skin, and that’s when we feel, “Ah, this is cool!”
“I wish it were even colder…” Everyone has thought this at least once, right? The market responded to this desire by putting a technology called the ‘Peltier element’—used in ice makers and small refrigerators—into handheld fans. This technology cools one side like an ice block when electric current flows, enabling fans that actually blow “cold air.” The phrase “air conditioner in my hand” is truly appealing. But this belief made us forget the most important fact: ‘What kind of environment am I in right now?’
Chapter 2: The Betrayer Appears, The Paradox of the Convection Oven
When the Breeze Turns Against You
Here is where the story changes. What if the air temperature around you becomes hotter than your body temperature? From this moment, the handheld fan turns from a helpful friend into a harmful enemy. Experts call this terrible phenomenon the ‘Convection Oven Effect.’
Our skin temperature is usually about 35℃. If the outside temperature rises above 36℃ or 37℃, the fan no longer cools our body heat but instead blows hot air like a hairdryer onto us. It’s like cooking meat inside a convection oven with hot air.
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Danger Signals from the Body
In this situation, our body goes into emergency mode. Because of the hot air, sweat doesn’t evaporate properly, and heat accumulates inside the body. Eventually, the core body temperature rises, the heart beats faster, and this can lead to heat exhaustion or life-threatening heatstroke.
The scariest part is that even hot air as “wind” tricks our brain into feeling “cool.” The brain thinks it’s okay, but the body is slowly deteriorating—this illusion of safety is what makes fans in heatwaves a “silent killer.”
Chapter 3: The Truth About 35℃
The Old Rule: “Stop Using Fans Above 35℃”
For a long time, many organizations including the World Health Organization (WHO) have recommended avoiding fan use when temperatures exceed 35℃. This was because of the ‘convection oven effect’ explained above. It was a well-known, firm rule.
A New Challenge to the Rule
However, in 2021, a research team from the University of Sydney questioned this old rule. They said, “The fan’s safety threshold is not necessarily 35℃!” Their argument was that the real important factors are not just the thermometer number but ’the surrounding humidity’ and ‘an individual’s sweating ability.’
In dry environments where sweat evaporates well, fans can still help even if the temperature exceeds 35℃. They proposed different safety standards depending on the situation.
| User Profile / Condition | Traditional Recommendation (℃) | University of Sydney Research (℃) | Key Determining Factors |
|---|---|---|---|
| General International Guideline | About 35 | - | Ambient Temperature |
| Healthy Young Adults | About 35 | 39 | Sweating Ability and Humidity |
| Healthy Elderly | About 35 | 38 | Sweating Ability and Humidity |
| Elderly on Certain Medications | About 35 | 37 | Medication-Induced Sweating Suppression |
These complex findings raise an important question: Should we follow a simple rule for everyone, or seek the precise truth tailored to our own situation, even if it’s more complicated?
Chapter 4: A Youth Lost in the Heat
Behind scientific debates, there is always a human life. The tragedy of a 27-year-old man Mr. K in the summer of 2024 shows how close this story is to our reality.
That day, a middle school cafeteria in Jeonnam was like a giant steam oven. The outside temperature was 34.4℃, but the temperature inside the sealed space without air conditioning was surely much higher. The only cooling devices were two fans.
Mr. K collapsed while installing an air conditioner there. He showed typical heatstroke symptoms such as delirium and vomiting, but unfortunately, his coworkers did not immediately recognize the severity. When he arrived at the hospital, his body temperature exceeded 40℃ and was unmeasurable; he never regained consciousness.
Mr. K’s death was not a simple accident. It was a preventable tragedy. And in that story, the two fans swirling hot air in the steamy cafeteria might not have cooled him but rather acted as a ‘convection oven’ blowing hot air, making his condition worse.
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Chapter 5: Wisdom to Control the Breeze
Now, we must learn to wisely manage this little breeze. Experts including the Korea Disease Control and Prevention Agency emphasize clear principles.
- Fans are a supporting player: Don’t rely solely on a fan during heatwaves. The main player is air conditioning or a cool place.
- Use with water: Wrap a wet towel around your neck or spray water on your body before using the fan. This maximizes evaporative cooling.
- Ventilation is essential: Use fans with windows open to let hot air escape.
- An excellent emergency tool: If someone suffers heat illness, wet their body and use fan breeze to quickly lower body temperature.
In conclusion, fans are not a ‘magic bullet’ that solves everything but a ‘helper’ that amplifies the effect of other cooling methods.
For the Informed User
Now, let’s return to the initial question: “Is it good or bad to use handheld fans during heatwaves?”
The answer is “It completely depends on when, where, and how you use it.”
We now know both faces of handheld fans—from the innocent friend we trusted to the threatening paradox of the convection oven. We learned that beyond the simple 35℃ rule, humidity and our body condition are more important variables.
We are now wise users armed with information. Finally, here are clear action guidelines for you.
✅ DOs
- Use fans when the temperature is below your safety threshold (37–39℃ for healthy adults) and when you are sweating.
- Always use with water. Wet towels or spray bottles create the best cooling system.
- Use fans for ventilation, especially to bring cool night air indoors.
❌ DON’Ts
- Don’t rely on a fan alone in temperatures above 35℃, especially in sealed, unventilated spaces.
- Don’t trust the sensory feeling of coolness alone; always check actual temperature and humidity.
- Never ignore symptoms like dizziness or delirium from heat illness. Call emergency services immediately.
Once again, on the steaming city streets, you hold your handheld fan. But now, you don’t switch it on carelessly. You check the temperature and humidity, listen to your body, and wisely decide how to manage this little breeze. The handheld fan is no longer a magical charm but a precious tool to be used with respect and understanding in a warming world.