How Long Does My Disinfectant Wipe Work?

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Q: I like to use wipes to disinfect surfaces in my home — especially surfaces that are frequently touched. But how much surface area can one wipe be used on before it loses its ability to kill the coronavirus?

A: The first step is to check the label on the wipes you're using. For instance, the label on a container of Clorox wipes instructs: "Use enough wipes for treated surface to remain visibly wet for 4 minutes. To kill viruses, let stand 15 seconds."

That time and that visible wetness is important, says Erica Hartman, an expert in environmental microbiology at the Northwestern University McCormick School of Engineering.

Regardless of the particular ingredients in the wipes you're using, "they're all chemicals that have to react," she says. "And those chemical reactions aren't instantaneous — they take a certain amount of time. So what you're doing when you're keeping the surface wet is you're basically allowing time, allowing the chemical reactions to take place."

So if that Clorox wipe isn't making the surface visibly wet for 4 minutes, you're trying to cover too much ground with one wipe.

There's no exact figure for how much surface area a wipe can handle. But a 2018 study that found one wipe is generally more effective over 1 to 2 square feet than 8 square feet.

And you don't need a pre-made wipe to clean surfaces: You can also use a liquid product on a cloth or paper towel. The Centers for Disease Control and Prevention advises using products that that contain bleach (sodium hypochlorite) or alcohol (at least 70%), and following the manufacturer's directions. You can make your own cleaning solution by mixing 4 teaspoons bleach per quart of water, according to the CDC.

The U.S. Environmental Protection Agency has posted a list of approved products to disinfect against the coronavirus.

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