(The Washington Post) — In hot weather like the kind we’ve seen this summer, fans are everywhere: they’re inexpensive tools that help us feel better in the heat.

The key word here is “feel”. In temperatures of around 90 degrees and higher, fans do very little to help us beyond tricking our brains into believing we’re not entering heat exhaustion. In extreme heat, fans may paradoxically make you hotter.

“There is no benefit to a fan. It doesn’t actually reduce body temperature,” said Glen Kenny, a professor of physiology at the University of Ottawa and the university research chair in human environmental physiology.

This is especially concerning for older adults who, studies have found, experience greater stress on the heart when using electric fans during high temperatures. The reason scientists think this happens is that electric fans increase air velocity and make our bodies gain dry heat. This also aggravates dehydration. Younger adults normally compensate by sweating more — after all, sweat is our bodies’ main way of cooling down — but we lose our ability to sweat as robustly when we age.

The Centres for Disease Control and Prevention recommends being in air conditioning at least a few hours a day during a heatwave, but that may not work in every situation.

So to make your fan more effective, try this: wet your skin first. Use a spray bottle or a sponge to intermittently apply cool tap water to the body — or better yet, if you can, drench your whole shirt. Studies have found that the combination of electric fans and skin-wetting — but not electric fans alone — can reduce heat strain in temperatures as high as 116 degrees. Wetting the skin works because when that water evaporates off our skin, it wicks heat away with it. That’s the entire reason sweating cools us off — but by wetting your skin from another source, you get all the benefits of evaporation while also reducing dehydration by about 50 per cent.

Last year, Kenny and his team published a study in JAMA studying the effects of electric fans among older adults. Participants aged 65 to 85 sat for eight hours in 96.8 degree heat and were allowed to drink as much water as they wanted, but some were randomised to an electric fan, while others weren’t.

You would think the fan-users would be cooler, but in reality, all groups reached the same level of hyperthermia and strain on the heart. The only difference, Kenny said, was that the fan-users “felt better” and looked happy as they approached heat exhaustion, while the group who weren’t using fans were acutely aware of their misery.

The mind trick occurs because fans soothe many of the body’s thermal sensors on the surface of our skin. These send a signal telling the brain that the entire body must be comfortable and that we don’t need to sweat so aggressively. But because fans don’t really cool your core, this can create a dangerous and false sense of security.

For one thing, it could lead people to change their behaviour, Kenny said. They might go out and buy groceries, take a walk outside or do other activities that push them over the brink of heat exhaustion.

“Feeling good from fans has nothing to do with the actual change in the body’s physiology. It’s just that those sensors that we have in the body are playing games with you,” he said.

It bears re-emphasising the importance of air conditioning during a heatwave (though there is a significant environmental cost). Even if you don’t have air conditioning at home, a visit to a shopping mall, public library or other air-conditioned environments is associated with a 67 per cent reduced risk of heat wave-related death.

Here are a few other science-backed tips that work:

• Use shading and natural ventilation to prevent heat from building up in your home. Close window shades during a sunny day and crack open a window to let out hot air; both can help keep indoor temperatures from cooking. When you get in your car on a hot day, open the windows to ventilate for a minute or two first; this helps the air conditioning work its magic more quickly.

• Hydrate. Even hot coffee on a hot day is perfectly fine. “It doesn’t really matter what temperature of water you drink while you’re sweating, because your body compensates for the ingested thermal load or sink enough to maintain core temperature,” said Nathan Morris, an assistant professor in human physiology and nutrition at the University of Colorado at Colorado Springs. He encourages people to drink whatever water temperature they find palatable to encourage greater fluid intake. If it’s humid outside or you’re exercising to the point that you’re dripping with sweat (meaning, it’s no longer evaporating efficiently), it makes the most sense to stick to cooler drinks. But if the situation that describes you best this summer is taking an afternoon break at your local café in a cute breezy dress, then don’t be embarrassed: order that hot espresso.

• Wear loose, breathable clothing like linen. Tighter and less breathable fabrics keep your sweat from evaporating easily — and remember, it’s the evaporation process that draws heat away from your body, not the sweat itself.

• Try wrapping ice in a damp towel and placing it on your neck. Applying an ice towel to the neck helps you lose heat via conduction and has been shown to reduce heat strain in certain conditions — namely, doing it in short bursts (for one to two minutes) and then repeating about every 10 minutes. Some of the strongest data supporting this comes from studies done during the Australian Open showing that among tennis players, the fan plus skin-wetting combination as well as the ice-towel method both effectively cooled body temperature by a full degree while reducing heart strain. There is a caveat, though: Kenny advises caution for older adults. In adults over age 65, this method may not actually reduce strain on their hearts.

We all know we should “stay hydrated,” but how much water anyone should drink in a day has been long debated. Over 20 years ago, the National Academy of Medicine recommended women and men drink around nine to 13 cups a day, respectively. At least eight cups a day is a rule of thumb that many people have heard, which probably stems from a misinterpretation of a 1945 recommendation from the Food and Nutrition Board of the National Research Council. A study published in Science in 2022 found that eight cups per day was unnecessary for most adults.

It’s reasonable to aim for around that much, but the most common-sense advice is to drink when you’re thirsty, prioritise water over sugary beverages, and, of course, pay extra attention to your increased needs in hot weather. If you’re doing intense exercise or reaching the point of dehydration, electrolyte-containing drinks can be helpful, but if you feel dizzy or light-headed, seek prompt medical attention.