Does a plastic face shield protect you and others as well as a mask?
Updated: Sep 2, 2020
Science is clear on the efficacy of face masks — it's proven to slow the spread of COVID-19. But what of face shields?
You’ve probably seen someone wearing one in your neighborhood. It’s basically an "individually sized salad bar sneeze guard attached to a headband."
The some advantages of a transparent plastic face shield over a face mask are apparent: easier breathing, clearer speech, and less chance of blinding fog on your glasses. Not to mention people wearing a full-face visor instead of a mask tend not to touch their mouth, nose and eyes as much. And, if you work in hospitality, it is helpful for customers to be able to see your beautiful smile.
Doctors, nurses, dental workers and other front-line health workers wear shields, but mostly as an added layer of protection in conjunction with masks. They're essential for intubation, which often causes to patients to expectorate violently. The shields also extend the longevity of the masks by blocking droplet contamination.
If someone coughs in your face, a mask won’t protect your eyes, but a shield will. And unlike face coverings designed for single use, such as surgical masks and N95 masks, plastic shields can be washed down and reused indefinitely.
However, the Centers for Disease Control and Prevention is clear on its guidance: Face shields are not recommended for “normal everyday activities or as a substitute for cloth face coverings.”
For one thing, it’s unknown how well shields, which have openings at the sides and bottom, protect others from droplets expelled by the wearer. Furthermore, the level of protection a shield affords to the person wearing it has not been thoroughly studied.
Let's dive a little deeper into the advantage and disadvantages of a face shield for prevention of COVID-19 spread, shall we?
Some benefits wearing a face shield...
They protect your eyes, in addition to the nose and mouth.
A face mask covers the lower part of the face but leaves the eyes exposed.
With a face shield, “you get the additional coverage of your eyes, another mucous membrane that may act as a portal of entry for the virus,” Erin Sorrell, an assistant research professor in Georgetown University’s department of microbiology and immunology, told HuffPost. “However, research needs to be done to quantify the risk for ocular route of exposure.”
They allow you to see people’s mouths and other facial expressions.
We all depend on non-verbal communication — like facial expressions — when interacting with others. But the ability to read lips is particularly important for those who are hard of hearing.
They’re easier to clean and safely reuse.
Disposable face coverings, like surgical masks, should be discarded after use (although, many have resorted to spraying the mask down with hand sanitizer spray and letting it air dry). Cloth facial coverings can be reworn but need to be washed (ideally in a washing machine) and dried after each use, which takes time. Whereas a face shield can be quickly and easily wiped down with disinfectant or soap and water.
They may be more comfortable to wear, making you less likely to touch your face.
“People who wear these homemade cloth masks are invariably touching their face constantly to adjust it, and we know that touching your face is one routine mechanism for infecting you,” Amesh Adalja, a senior scholar at the Johns Hopkins University Center for Health Security, told NBC News. “When you’re wearing a face shield, you’re less likely to touch your face.”
Face shields may also be a more comfortable option for people who wear glasses or who have trouble breathing while wearing a mask, Sorrell added. Plus, pulling your mask up and down without washing your hands first can lead to contamination.
“A properly worn face shield is much more effective than a face mask that is removed when speaking or worn under your nose or around your neck,” Sorrell said. “If you aren’t going to wear and use a face mask properly, you are not going to be protected or protect others.”
..But they have other limitations and disadvantages, too.
Masks provide a closer seal to the wearer's face
Unlike masks, which “provide a closer seal to the wearer’s face,” Sorrell said, face shields are open on the sides and bottom of the face, which may allow particles to seep in or out.
“If you’re facing sideways or I’m behind you, maybe you’re sitting at a desk and I’m standing, there’s other scenarios you can imagine where droplets can come around a face shield,” William Lindsley, a NIOSH bioengineer who conducted the influenza study, told The New York Times.
While a face shield may do a good job at blocking larger viral particles, Lindsley said that cloth facial coverings or medical masks offer more protection from tinier ones.
“A face shield is good against the really big stuff [particles] that you can kind of see,” he told NBC News. “But as the stuff gets smaller and smaller, it’s just easy for that to go around the face shield and be inhaled.” Since studies suggest that COVID-19 is spread through airborne transmission via aerosols (or, those tiny particles mentioned), without more research one cannot say that a face shield, alone, can protect against the spread of COVID-19 as well as a face mask or covering.
Thus! Until we have more research, a face mask is your best bet.
“We don’t have enough large-scale data to show the true effectiveness of face shields against COVID-19 compared to face masks,” Sorrell said. For now, if you’re going to wear a face shield, you should do so in addition to — not in lieu of — a face mask.
However, “the average person who wears a face mask correctly and maintains social distancing does not need the added layer of a face shield,” Sorrell noted.
And, of course, any protective gear should be used in conjunction with other safety measures, such as physical distancing and frequent hand washing, not in place of them.
Though if you are going to opt for the face shield in leu of a face mask or covering, please note that a proper face shield should extend down below the chin, around the sides of the head to the ears and have no gap between the headpiece and the forehead.