Which one ensures better protection: face shield or face mask?

Courtesy: Getty Images

By now most of the people wear face masks when they go outside to protect themselves and others from getting infected by COVID-19. But face masks in this hot and rainy weather can be irritating for the skin. And foggy glasses, make it difficult for people to see. Also, breathing gets quite difficult with cheap masks. People also face difficulties in communication with mouth covered, muffling voices and hiding facial expressions.

Figure: Face shields have been a key part of personal protection equipment for frontline health workers. Courtesy: Getty Images

On the other hand, research on face shield is limited but promising. In a 2014 Journal of Occupational and Environmental Hygiene study, researchers at the National Institute for Occupational Safety and Health placed a face shield on a breathing robot and had another robot 18 inches away ‘cough out’ flu virus. The shield prevented the breathing robot from inhaling 96 percent of the virus within five minutes.

In additional tests, the shield’s effectiveness varied based on the size of droplets expelled, most frequently used in health care settings. On the other side, Health officials in Switzerland recently warned that shields alone may not offer as much protection as masks alone; in a recent outbreak at a hotel, some employees and a guest who wore plastic visor-style shields tested positive for COVID-19, while those who wore masks did not.

Amesh Adalja, M.D., a pandemic preparedness expert at the Johns Hopkins Centre for Health Security, says, “There’s a lot of at least biological possibility to suspect that [shields] are better than homemade face masks, and maybe even better than other types of masks as well because they not only prevent you from spreading it … [and] because it also covers your eyes, it provides more protection to the mucus membranes of your face where you might be getting infected.”

On another side says Adalja, “With a mask, you may find yourself constantly adjusting it and therefore touching your face and possibly transferring the virus from your hands, but wearing a shield does not put you in a position where you are touching your face so much, because it is not as cumbersome to wear.”

Finally, Adalja adds, “If you walk down the sidewalk, you can find lots of masks that are just discarded there, which are an infection control risk for other people. Whereas a face shield is something that people can just clean themselves and reuse.”

Masks are now ubiquitous, but face shields are taking on their role as the coronavirus pandemic continues to grow. Qatar Airways is requiring passengers and crew to wear both face masks and face shields on flights.

The Centres for Disease Control and Prevention continues to recommend wearing “cloth face coverings in public settings where other social distancing measures are difficult to maintain.

Finally, who are concerned about the potential role of aerosols, or who might be at high-risk for the coronavirus, they take the solution as like to wear shields and masks at the same time, suggests William Lindsley, Ph.D., a bio-engineer with the National Institute for Occupational Safety and Health.

When robots wore both shields and masks in his study, the shields blocked 97 percent of the virus from landing on the masks, keeping them much cleaner.  The face shield protects the wearer, but face masks protect everyone else around them.

Of course, no matter what someone wears on the face, the most important thing to remember is to wash hands and practice physical distancing whenever possible.