This common ‘heatwave mistake’ could harm your health as temperatures soar over 95 degrees this weekend

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The thought of heading into another brutal heatwave this weekend may have you feeling like a heat-pummeled, melting face emoji unable to get off the couch. For me, that’s compounded by the fact that I don’t have air conditioning anywhere in the house but for a small, rickety wall unit in the bedroom — and only installed recently.

Instead, I use multiple electric fans to create a cross breeze, often sticking my sweaty, flushed face directly in front of the fan grill.

Do not do this.

According to the Centers for Disease Control and Prevention, using electric fans in a heatwave of 90 degrees or more can actually make you hotter and can be dangerous for your health. Why? The fan acts as a convection oven, an appliance that circulates hot air in order to cook food quickly and evenly. In your home, during a heatwave, electric fans do the same: blow extra hot air around, potentially raising your body temperature instead of cooling it down. And that puts you at an accelerated risk for dehydration and heat exhaustion.

“It’s definitely true that if you’re blowing air warmer than your skin over your body, then you’re warming your body,” says David Eisenman, professor of medicine and co-director of the UCLA Center for Healthy Climate Solutions. “That heatwave mistake can be harmful. You’re warming yourself up and it increases the temperature inside your organs, including the heart and the brain and the blood. That can lead to dehydration, heat illnesses, and it can lead to cellular breakdown that makes heart disease or any other chronic illnesses that people have worse.”

It’s important to note, however, that the CDC’s temperature threshold is conservative, Eisenman says. Normal body temperature is about 98.6 degrees. Your skin — the surface of your body — is closer to 95 degrees. “That’s why international bodies, like the World Health Organization, say 95 degrees is the limit at which you should no longer use fans,” he says. “A young healthy person can still use their fan if it’s less than 95 degrees.”

The CDC chose 90 degrees as its fan safety cutoff point because “it fits all age groups and all circumstances,” Eisenman says, adding that humidity, age and the temperature inside someone’s home — which can be hotter than outside — could all make the safety threshold for using fans lower than 95 degrees. “When you’re doing math messaging, you have to have one simple message for everyone,” he says. “The CDC got more conservative and said let’s drop it down a few degrees. I think we should stick with what the CDC says.”

This weekend is expected to seehighs of 95 to 110 degrees in the valleys, with portions of the Antelope Valley potentially reaching 115 degrees, and 100 to 110 across the Inland Empire. So are those of us without AC just out of luck?

Not necessarily.

Eisenman and V. Kelly Turner, associate director of heat research at the UCLA Luskin Center for Innovation, shared strategic tips for keeping cool sans fans.

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Ice out

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Eisenman suggests putting a bowl of ice, or frozen bottles of water, in front of a fan grill to create a “misting experience.” The fan then acts like a mister. “That mist is cooling, especially if you’re close to it and you feel the moisture on your skin,” he says. “If it’s on the other side of the room, it’s not going to help. You have to feel moisture on your skin.” He also recommends misting your skin with a spray bottle — “like a bottle you use to spray your plants with” — every five or so minutes, keeping your skin visibly wet. “Spray your face, your arms, your legs, your chest — any skin. As long as it’s visibly wet, it’s helping you.”

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Prep at night

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Turner says that fans are actually “great at nighttime.”

“It’s self-reinforcing: you ventilate at night, then shield from the sun by day, and it works well,” she says. “So you should open the windows, turn on the fans, get air circulation going and ventilate — even if it’s under 70 degrees in the evening. Then, in the morning before the sun comes up — 6 a.m. or so — you’d pull your shades down and pull them back up at 8 p.m. and ventilate again.

That preparation is key, Turner says.

“If you don’t start doing that [ahead of time] and, say, you have a hot starting point because you didn’t ventilate at night, then you’re trapped in hot conditions,” she says. “The more you pair those things — [ventilation and shade] — and stay on a good cycle, the better off you’ll be.”

Eisenman adds that fans can cause more water to evaporate from your skin in dry conditions such as L.A., further drying you out. “So if you put a fan on at night, you need to drink a lot more water when you wake up in the morning,” he says. “Two glasses at least when you first wake up.”

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Get damp

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Both Eisenman and Turner recommend cooling your body temperature with cold compresses or cool showers. Leave a damp towel in the fridge or freezer and apply it to your neck and chest, the top of your head and your lap for one to two minutes. Repeat every 10 minutes or so. “Adding that to big surface areas of the body really helps cool you down,” Eisenman says.

Along those lines, Eisenman also suggests a cool or lukewarm shower before bed. Better yet: soak a T-shirt in cold bath water and wear it to bed. Or sleep on top of a wet towel. “That’s what I do,” he says. “It keeps your body cool.”

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Hydrate. Duh

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It may be obvious, but is worth repeating: “hydrate,” say both Eisenman and Turner. Drink water frequently throughout the day before you feel thirsty.

“If you’re feeling thirsty, you’re already dehydrated,” Eisenman warns. “That’s especially true for older adults whose thirst sensation may be impaired. As you get older, your brain’s ability to distinguish when you’re dehydrated and create that feeling of thirst diminishes. That’s also true for some people on medications.”

Monitor the color or your urine, Eisenman adds, which is a good indicator of your hydration level. It should be pale yellow or as close to clear as possible.

And in a pinch, ditch your home entirely and find a public space to stay cool. Jump into an affordable public pool or hunker down at a public library, free museum, or one of the city’s public cooling centers.

See you on the other side of this heatwave.