As you step into the grocery store, you get hit with a blast of cold air. You wonder: Am I entering Whole Foods or the Arctic Circle?! It’s not your imagination—stores direct a polar wind your way as you push your cart through their doors to grab some groceries. But why?

To find out the reason for that icy entrance (one of many grocery shopping secrets you should know), we turned to two experts. Here, they explain the reason for that wind tunnel from hell and spill the tea on how stores keep their aisles cool enough to keep food safe—but not so frigid that we’re all running for the exits.

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How low do grocery stores keep the temperature?

Workplaces, including grocery stores, should ideally fall between 68 and 78 degrees, according to recommendations set by the Occupational Safety and Health Administration (OSHA). While there is no scientific research on grocery store temperatures, the U.K.-based publication Daily Mail did a boots-on-the-ground investigation a decade back and found some London-area grocery chains dipped as low as 43 degrees Fahrenheit—brrr! As anyone who has booked it through the freezer aisle in a T-shirt might guess, that and the meat aisle were the coldest in the Daily Mail’s report.

Keep in mind that stores aren’t trying to ice you out. They have some open display cases and need to make sure the food doesn’t spoil, our experts point out.

“Stores also keep it cool for operational reasons—large refrigeration units generate a lot of heat, so the overall temperature has to be balanced to prevent them from overworking,” says Ryan Figlia, a New York–based airflow expert and the co-founder of Windmill, a modern air products and technology company. “If you find yourself shivering in the aisles, it’s actually a good sign that the store is being smart about its climate-control solutions (and food preservation).”

What’s with the cold blast of air right at the store entrance?

Air curtain vent above a business's entrance doorsbeekeepx/Getty Images

As cold as grocery stores can be, they’re even more frigid right when you enter. Keep reading to find out why.

It serves as an air curtain

That cold gust that hits you is an air curtain—also known as an air wall or an air door. “An air wall is essentially a blast of air that acts through pressure to create a temperature buffer,” says Benjamin Lorr, the New York–based author of The Secret Life of Groceries. So it keeps the cold inside air in and the outside temperatures, whether balmy or bitter cold, out. “If you look up at the entrance, you’ll usually see a rectangular fan doing that blasting,” he adds.

This genius bit of engineering, which dates back over 100 years, “serves a real purpose—it creates an invisible barrier between the inside and outside, helping to keep the store’s temperature stable,” explains Figlia. “Without it, every time the doors open, hot or cold air would rush in, making the store harder (and more expensive!) to heat or cool.”

It keeps insects and pollutants out

That air door also acts as a gatekeeper—in a good way—stopping dust, odors and pests from gaining entrance, according to the Air Movement and Control Association International (AMCA), a nonprofit trade organization for the air-systems industry.

“The steady stream of air creates a force field that makes it much harder for flying insects to enter since they struggle to fly against the airflow,” Figlia explains. “While it’s not a 100% foolproof solution, it’s a big reason why you don’t see swarms of flies buzzing around the produce section.”

It saves on heating and cooling costs

High-traffic doorways with air curtains save energy compared with doorways without this air circulation feature, according to the U.S. Department of Energy’s Office of Scientific and Technical Information (OSTI).

“Air doors help grocery stores save on heating and cooling costs by reducing how much air escapes when customers come and go,” says Figlia. In a smaller, less high-tech market, you may see dangling weather strips of heavy plastic that basically serve the same purpose.

What else can air curtains do?

Air curtains aren’t just for grocery stores. You might notice one as you step onto your next flight. A study published in the Journal of Economic Entomology found that air curtains kept mosquitoes and houseflies from boarding an aircraft.

Air curtains are also being studied as a way to curb the spread of nasty bugs—the infectious kind, that is. A 2020 study found having an air curtain on a doctor’s desk facing the patient reduced the germs flying the doctor’s way by 70% to 90%. So if you get hit with a fan at your next doctor’s visit, you’ll know it’s there to boomerang your virus particles right back at you. Gee, thanks doc.

About the experts

  • Ryan Figlia is an airflow expert and the co-founder and head of manufacturing at Windmill, a modern air products and technology company in New York City. He has more than 20 years of experience servicing and manufacturing commercial HVAC units.
  • Benjamin Lorr is the author of The Secret Life of Groceries: The Dark Miracle of the American Supermarket. He is a journalist in New York City.

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