The majority of countries around the world now require their citizens to wear a face-mask when they leave home. And while we now have a more straightforward path out of lock-down, it’s likely masks will be around for a while.
Meanwhile, people in other cities with outbreaks have been encouraged to wear masks, and some people are simply choosing to wear one as a precaution. But some people in their community, instead of opting for a traditional mask, are instead wearing a face shield. This might offer some degree of protection — but it’s probably not as good as a mask in preventing the spread of the Corona Virus.
What really is a Face-Shield?
A face shield is a film made from plastic or other transparent material designed to be worn like a visor. It’s attached using a band that goes around the top of your head.
Think of a visor a welder wears to protect themselves from sparks and injury. Health-care workers use face shields to block bodily fluids from coming into contact with their faces and potentially causing infection.
Many people likely choose face shields during COVID-19 because they’re experiencing discomfort wearing a mask — whether glasses fogging up, irritation around the ears, or just that extra layer.
The term “face covering,” as per the some of the government’s guidelines, is notably vague. It can include a face mask, a face shield, or a scarf or bandana.
Are Face Shields really effective?
A letter, published recently in the journal Physics of Fluids, reported on a laboratory experiment where scientists put face shields to the test.
They simulated coughing by connecting the head of a mannequin to a fog machine and then using a pump to expel the vapor through the dummy’s mouth.
They found that while face shields stopped the droplets being propelled forwards, aerosolized droplets — those much smaller in size — lingered at the bottom of the shield and floated around at the sides. They eventually spread approximately 90 centimeters from the mannequins.
This exciting laboratory experiment, but not conclusive evidence, face shields that offer less protection than masks in the community.
A lack of research on the effectiveness of face shields means it’s impossible to make any firm recommendations for or against their use.
What’s in it for us?
There’s a lot we still don’t know about this virus and how it spreads.
At present, we believe the virus is spread generally through close contact with an infectious person, communication with the droplets emitted when they sneeze or cough, or contact with surfaces these droplets have contaminated.
To establish an infection, the virus enters your body through portals of entry: the mouth, nose, and eyes.
Wearing a mask is intended to protect others if you have the infection, by blocking the droplets from your mouth and nose. We call this source control. To a degree — though we have less evidence on this front — it’s also likely to protect you, the wearer, by providing a physical barrier to your entry portals.
A face shield may offer an advantage in that it provides a physical barrier over all your portals of entry — your eyes and mouth and nose. Shields may also reduce the frequency of the wearer touching their face, and have the added benefit of allowing the person’s face to be seen (if they’re not wearing a mask as well).
However, as they’re not tight-fitting, aerosols may still enter and exit around the outside of a face shield, where it’s not fitted in the same way a mask is. And we’re continuing to accumulate evidence about the possible role of aerosolised transmission in the spread of COVID-19, which the World Health Organisation is closely monitoring.
Proper use plays a very important role
Whatever face covering you choose, you must use it properly, and it must fit correctly.
Having masks slung under the chin, hanging off one ear, or your nose poking out over the mask’s top will make them markedly less effective. And of course, frequently touching and re-adjusting the mask means we’re possibly contaminating our hands too.
If you don’t intend to wear a mask properly or unable to, then a face shield is a better option. You can also wear a mask and a face shield together, which will give you a better protection.
Like masks, there are a variety of face shields available, varying in quality and size. If you wear a face shield, the department of health advises it should cover “the wearer’s forehead to below the chin area and wrapping around the sides of the wearer’s face.“
It would be best if you did not share a face shield. If they’re labeled disposable, don’t reuse them. And if they are reusable, you need to clean them regularly following the manufacturer’s instructions.
Masks worn correctly are the best option. When wearing a mask is not possible, then a face shield is better than nothing. Neither will work well if not appropriately used, and importantly, they don’t replace physical distancing and hand hygiene.