As we prepare for the return to school, I wanted to highlight some significant differences between face masks and face shields.
From personal experience, I can honestly say I prefer a face shield to a face mask for functionality. The breathability feels unrestricted and my glasses don't fog up. People can hear my words more clearly, read my lips and see my facial expressions better with a face shield. As a result, communication feels relatively normal. The one functional drawback is that I forget I'm wearing it and have smashed food and beverage into the shield. You can witness this phenomenon "in the wild" here.
So why can't I fully recommend you should only wear a face shield or only a face mask? Well, the most important aspect of choice when it comes to protection is safety. There is ample evidence to suggest that face masks do a better job than face shields of containing aerosol droplets exiting the mouth and nose. There is also evidence that face shields protect our eyes better. Doctors are not yet sure how vulnerable our eyes are to a COVID-19 infection, but there is evidence to suggest we are vulnerable.
In our school community we have high-risk members and, for me, the classic phrase applies: "Better safe than sorry." My recommendation is to use both, as the situation dictates. When I am indoors with others, I plan to wear both. When I am teaching in class and have plenty of distance (at least 6 feet) between my students and me, I will wear just the face shield. And when I circulate through the classroom to help students individually, I will wear both again.
Another article that highlights the aerosol effect of breathing, speaking, singing, coughing and sneezing and why facemasks do a much better job of containing aerosol droplets than face shields can be found on the BBC website here.