Fans Can Help In High Heat – But Only If You Use Them Right

Electric fans can feel like a lifeline during hot weather.
However, their effectiveness depends on how hot it is and how they are used.

New research suggests fans may still help at higher temperatures than once believed.
But they must be used correctly to avoid increasing heat strain.

When Fans Can Help You Cool Down

For years, the US Centers for Disease Control and Prevention (CDC) advised against using fans above 32°C (90°F).
The concern was simple: hot air can add heat to the body instead of removing it.

Recent findings, published in JAMA Network Open, paint a more nuanced picture.

Fans at Moderately High Temperatures

Researchers found that at 38°C (100°F) with moderate humidity, fans can still help.
They reduced strain on the heart and slightly lowered internal body temperature.
Participants also reported feeling more comfortable.

These benefits were seen even in adults aged 65 and above, including some with heart disease.

 

When Fans Can Become Risky

There is a clear tipping point.

At 40°C (104°F), fan use caused signs of body heat gain.
This increases the risk of heat exhaustion and heat-related illness.

The World Health Organisation sets a similar upper safety threshold.
Above this level, fans may do more harm than good.

Why Hydration Is Essential

Fans only work if the body can sweat.

Sweating cools the body through evaporation.
A fan speeds up this process by increasing air movement across the skin.

Without enough fluid, this cooling system fails.

How Much Water Is Needed?

In the study, participants drank about 230 ml (8 ounces) of water per hour.
They did not wait until they felt thirsty.
Instead, they sipped water regularly.

Skin Wetting Makes Fans More Effective

Another key finding involved skin wetting.

When participants sprayed water on their skin, fans worked better.
Heart strain was reduced, even at very high temperatures.
People also felt slightly more comfortable.

Practical Ways to Wet the Skin

• Use a spray bottle

• Apply a damp cloth to the skin

• Mist exposed areas regularly

The skin needs to stay wet for this method to work.

Be Careful with Indoor Heat

Indoor spaces can sometimes be hotter than outdoors.
Poor ventilation and trapped heat can raise indoor temperatures quickly.

Always check the room temperature before relying on a fan.
If possible, improve airflow or use air conditioning briefly before switching to a fan.

Warning Signs to Watch For

Stop using a fan and leave the heat if you notice:

• Dizziness

• Nausea

• Headache

• Blurred vision

Seek medical help if symptoms persist for more than an hour.
Get immediate care if there is confusion, fainting, or vomiting.

The Bottom Line

Fans can help in high heat — but only under the right conditions.

They work best when:

• Temperatures are below extreme levels

• You stay well hydrated

• Skin wetting is used

Used incorrectly, fans can increase heat stress.
Knowing when and how to use them can make hot days safer. PRIME