科普 | 为什么虽然有免洗消毒液，但是我们还是要勤洗手？
Why sanitizer works, but hand washing works better
An expert guide to the great hand sanitizer debate.
By Sara Kiley Watson
March 5, 2020
Washing your hands with soap is your best defense from viruses and bacteria, but hand sanitizer is a close second.Image by Martin Slavoljubovski from Pixabay
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If you haven’t gotten the memo to wash your hands regularly, especially now with COVID-19 floating around, it’s time to break out the soap and get scrubbing. But something that’s not as clear is whether you should stock up on hand sanitizer, or even make your own if the Amazon prices are giving you heartburn.
So, what do the experts recommend? Wash your hands whenever possible, and if you can’t get to a sink, sanitizer is good, too (both the kind from the store and the kind you can make). Here’s the breakdown of why soap comes first, and why sanitizer has its pros and cons.
What is sanitizer, and how does it work?
Hand sanitizer is essentially isopropyl alcohol, plus gel, plus fun-smelling essential oils if you’re so inclined. At first, hospitals and other healthcare centers used the solution as a quick fix for doctors who didn’t necessarily have a second to go to the restroom to disinfect between patients.
The way sanitizer works is primarily through the power of alcohol. Alcohol can “murder” many types of bacteria and viruses by destroying their outermost layer, rendering them unable to take over a host. This isn’t effective with viruses with a hard outer shell, like norovirus. Still, in a pinch, it’ll keep you protected from a lot of the invisible gunk you might pick up on mass transportation or a public restroom.
Soap works a little differently. Instead of killing viruses and bacteria, its purpose is to lift away dirt, oil, and other dangerous agents that get on your hands. Sanitizer doesn’t remove anything: It only disinfects bacteria and viruses and can leave pesticides or spores on your hands.
Washing away the coronavirus might not sound as violent as stopping it dead in its tracks, but it’s proven to be more effective, especially for pathogens wrapped up in mucus.
“There isn’t anything where the alcohol is really better than effective hand washing,” says Preeti Malani, a medical professor focused on infectious disease at the University of Michigan.
Is it possible to over wash my hands or use too much sanitizer?
Not really, says Sanjay Maggirwar, the chair of George Washington University’s department of microbiology, immunology, and tropical medicine—though constantly lathering your hands or dousing them with Purell will probably dry them out. So be ready to be extra efficient when it comes to moisturizing. “Other than that, there’s not much harm in it,” Maggirwar says.
To properly use sanitizer, plop around three millimeters (about the size of a sequin) of product onto your palm and rub for at least 10 to 15 seconds until your hands are dry. You can do this whenever you feel it’s necessary ... just be conscious of the drying power of alcohol.
The one thing that can be a little tricky is that sanitizers or soaps with ingredients like triclosan might up the risk of antibiotic resistance; these additives haven’t proven to do much to benefit your hand washing and sanitizing regimen. But Maggirwar hasn’t seen bacteria and viruses grow resistant to alcohol or regular old soap. If you’re looking at the label on your bottle and it says “antimicrobial,” you also don’t need to flip out. Use what you can to stay clean and healthy.
So, should I make my own hand sanitizer?
This is up to you. If you’re using isopropyl alcohol and a gel like aloe vera, it’s easy to make and won’t be all that different from what you can buy in the store.
“Shake it up good, and that stuff is gonna look and smell and feel just like Purell,” says Jack Caravano, a clinical professor of environmental public health at NYU. But be careful using more nontraditional recipes, like this one that calls for vodka. You want your hand sanitizer to be at least 60 percent alcohol, so you’ll need an intense liquor around 150 proof or higher, Caravano says.
If you’d rather not concoct your own coronavirus killer, that’s okay, too. “It doesn’t seem like a good use of vodka to me,” Malani says. Just be sure to keep washing your hands as regularly as you can, especially after touching shared surfaces. Also remember to regularly disinfect surfaces at your home or office that are at risk of being sneezed on. It might be smart to wipe down your cell phone, too, if you happen to use that a lot on the run.
Then, instead of using it for your hands, you can shake your alcohol up for a drink and make waiting out this outbreak a bit more fun.