Have I Been Cleaning All Wrong?

Many household disinfectants promise to kill 99.9 percent of germs, but some of us might be cleaning too swiftly to let them do their job.

Ever since the coronavirus became a threat, many of us are doing a lot more cleaning at home, spraying and wiping pretty much everything in sight, especially high-touch surfaces like door knobs and faucet handles.

But many of us are used to giving a surface a quick spray, followed by a wipe or two, which may not allow enough time for the product to work. And once you start reading labels on cleaning products closely, it gets really confusing. Several readers pointed out that disinfectant wipes and spray cleaners have different instructions on their labels for how long a cleaner should stay on a surface to effectively kill germs, ranging from 30 seconds to four minutes or even as long as 10 minutes. What’s more, some labels recommend cleaning before using a disinfectant.

So what’s the right way to clean? We talked to infectious disease scientists and microbiologists who study and test cleaning products to answer your questions about cleaning in the time of coronavirus. The bottom line: Whether you’re worried about coronavirus or other germs that lurk in our homes, many of us are cleaning too fast for the disinfectant to do its job.

Here’s what the experts said.

How long does a disinfectant need to stay on a surface in order to kill germs?

You probably need to let your disinfectant stay on the surface you’re cleaning for far longer than you think.

“The longer you can let it be in contact, the better,” said Dr. Andrew Janowski, instructor of pediatric infectious diseases at Washington University School of Medicine St. Louis Children’s Hospital. “What I’ve been doing at home: I wait roughly a minute if I’m applying a spray product and then wiping.”

To find out how long the recommended time is for a specific product, check the label. The guidance could range from 30 seconds to several minutes of contact time before you wipe. Note that some products may claim to sanitize, which means they reduce the level of certain bacteria, but not viruses. A disinfectant claim means the product destroys or inactivates both the bacteria and viruses noted on the label.