Does Steam Kill Viruses?

Before you take a handheld steamer to every surface in your home, find out what the experts have to say about whether steam can really kill viruses.

Luckily, it's now easier to find disinfectants in stores and online than it was early on in the pandemic, but it's still a toss-up whether you're going to find your usual cleanser or spray available when you really need to restock.

If you didn't stock up on bleach wipes and cleaning sprays before the big rush of panic buying at the start of the pandemic, you probably remember trying different cleaning hacks. But what about steam? This alternative idea has been circulating for some time now. Yes, we're talking about that vapor that cooks broccoli and gets wrinkles out of clothes. So, does steam kill viruses?

Some companies that make steamers claim that a blast with a steamer on soft surfaces such as upholstery can kill up to 99.9 percent of pathogens — which, for comparison, is the same track record claimed by many makers of bleach wipes and disinfectant sprays. Companies don't go as far as to say that steam can kill viruses on hard surfaces or take out SARS-CoV-2, the virus that causes COVID-19 (aka novel coronavirus), but this does beg the question does steam kill viruses enough to utilize it as a backup virus protection tool?

Using a steamer seems like a great cleaning solution if you don't have disinfectants handy or even if you prefer to clean your place without chemicals, but what do experts have to say?

Does Steam Kill Viruses?

Actually, under certain circumstances, yes. "We use steam under pressure to kill viruses in autoclaves," says William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine. (An autoclave is a medical device that uses steam to sterilize equipment and other objects.) "Steam is how we sterilize medical equipment that we use in the laboratory," says Dr. Schaffner. (To get the germs out of your kitchen, use these cleaning tips.)

However, that steam is used in a controlled setting under pressure (which allows the steam to reach higher temperatures), and it's unclear if steam would be as effective against SARS-CoV-2 or any other virus on a surface like your kitchen counters. "I'm not sure whether the time-temperature relationships that you would use when you're steaming a countertop, couch, or hardwood floor, would kill the virus," says Dr. Schaffner. There's no research on steam being used this way but, in theory, it might work, he adds.

As far as what the Centers for Disease Control and Prevention (CDC) has to say, the organization recommends that soft surfaces like carpets, rugs, and drapes be cleaned with basic soap and hot water. And for other frequently touched surfaces like tables, doorknobs, light switches, countertops, handles, desks, phones, keyboards, toilets, faucets, and sinks, it's suggested that you disinfect these using a diluted bleach solution, an alcohol solution with at least 70 percent alcohol, and products that are on the Environmental Protection Agency's disinfectant list.

If you're interested in using a steamer to clean surfaces in your home, Ruth Collins, Ph.D., an assistant professor of molecular medicine at Cornell University, recommends this hack to up your coronavirus protection: Lather up your counters with soap and hot water, and follow that with a good blast of steam to kill germs. While this coronavirus disinfecting method hasn't been backed up by research, Collins points out that soap is known to dissolve the outer layer of SARS-CoV-2 and kill the virus. High temperatures can do the same. Together, she says, it should kill SARS-CoV-2, but again this isn't foolproof and shouldn't take the place of CDC-approved cleaning solutions.

Coronaviruses are enveloped viruses, meaning they have a protective membrane of fat, explains Collins. But that fat is "sensitive to detergent," which is why the soap is a good partner, she says.

Steam may be effective on its own, but adding the soap is like extra insurance, says Collins. "If you put a thin film of soapy water down first and then come in with steam, you'll have maximum penetration," she says.

Collins isn't as sure about how well steam would work to kill pathogens on softer materials, like clothes, couches, and rugs. However, when it comes to clothes, it's really best to just toss them in the washing machine, says Richard Watkins, M.D., an infectious disease physician in Akron, Ohio, and a professor of internal medicine at Northeast Ohio Medical University. "Wash your clothes in hot water if you're concerned about COVID-19 on your clothes," he says.

So, does steam kill viruses? Experts are split: Some believe it works as an addition to other cleaners such as soap and water, while others don't think steam can be as effective at killing viruses in real life as it is in a controlled lab setting. It's important to reiterate that using steam as a way to kill viruses is not currently a disinfectant method approved by the CDC, the Food and Drug Administration (FDA), or the Environmental Protection Agency (EPA). That doesn't mean it can't work, or that it would do any harm to your health if you added it to your cleaning routine; it's just not something those organizations recommend at this point.

That said, if you want to give steaming a try and you've been thinking of getting a hand-held steamer to get wrinkles out of your clothes or a steam mop for your floors, there's no harm in trying this. Just know that it may not be 100 percent effective. "Bleach and EPA-approved disinfectants are still your best bet," says Dr. Schaffner.

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