When it’s hot, fans promise quick cooling. But at what temperature do they do more harm than good? We will show you when fans make sense and give you concrete decision-making assistance.
The World Health Organization (WHO) is clear: “Use fans only at temperatures below 40°C. At temperatures above 40°C, fans heat up the body.”
The most important rule: 40 degrees is the limit for fans
The science behind it: Our body cools itself through sweat evaporation. A fan helps by blowing away the moist air – but only if this air is cooler than our body temperature (approx. 37°C). At over 40°C it literally blows hot air onto the skin. Instead of cooling, additional heat is supplied, which can lead to overheating
Your decision-making aid: fan yes or no?
Green light at temperatures below 35°C:
- Use the swivel function instead of blowing on it directly
- Test carefully if you have allergies or asthma
Be careful between 35-40°C:
- Pay attention to how your body feels
- Take breaks after prolonged use (muscle tension)
- Be especially careful at night
Switching off above 40°C:
- Follow WHO recommendation
- Stop immediately if there are signs of overheating
What you can do instead in extreme heat
If the fan becomes counterproductive, other measures can help: cool showers, wet wipes on the wrists and neck, light clothing and regular drinking (1 glass per hour). It feels up to 10°C cooler in the shade than in the sun.
Health and common myths
In addition to the 40 degree rule, there are other health aspects surrounding fans – some are real, others are myths that have long been debunked. Muscle tension arises from direct, one-sided cooling of the head, neck or shoulders. Allergy sufferers should be careful as fans stir up pollen and dust.
Cold myth cleared up: drafts alone don’t make you sick – only viruses cause colds. It only becomes a problem if you have a weakened immune system or if you are cold due to the draft.
Environment and costs
Fans consume around 50-75 watts, while air conditioning systems use 2000-3000 watts – which makes them around 30-40 times more economical.
Conclusion: Fans are an energy-saving aid in moderate heat. However, above 40 degrees they become counterproductive and can increase overheating instead of preventing it. Taking the WHO limit seriously is more important than any supposed cooling.
Read more on Techzle\.com:
- 12 common mistakes that make you sleep worse in the heat
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- 10 tips against sunburn – sun protection factor is not everything
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