With the coronavirus in the United States still spreading at an alarming rate, it seems that the country as a whole, at long last, is finally realizing how important it is to adhere to CDC safety guidelines. These days, many stores across the country won’t even let you inside if you’re not wearing a face covering some sort. Even holdouts like Winn-Dixie have bowed to public pressure and now require shoppers to wear protective coverings before entering. While most people generally tend to opt for a surgical mask or another type of cloth covering over their face, every once in a while, you run into somebody wearing a face shield. And while a face shield might seem like an adequate substitute for a face mask, the CDC makes a point of noting that they are not recommended and are not nearly as effective as you think. As the CDC makes clear, there’s no evidence to suggest that face shields provide an equivalent safety benefit to masks and other face coverings:
It is not known if face shields offer any advantage as source control to protect others from the spray of respiratory particles. CDC does not recommend using face shields for regular activities or as a substitute for cloth face coverings. Some people may choose to use a face shield when sustained close contact with other people is expected. If face shields are used without a mask, they should wrap around the sides of the wearer’s face and extend to below the chin.
Further, a 2014 study titled “Efficacy of face shields against cough aerosol droplets from a cough simulator” found that face shields, while beneficial in the immediate aftermath of a cough, are not as effective against smaller aerosol particles which can sometimes remain in the air for more extended periods of time:
Our results show that healthcare workers can inhale infectious airborne particles while treating a coughing patient. Face shields can substantially reduce the short-term exposure of healthcare workers to large contagious aerosol particles. Still, smaller particles can remain airborne longer and flow around the face shield more easily to be inhaled. Thus, face shields provide a useful adjunct to respiratory protection for workers caring for patients with respiratory infections. However, they cannot be used as a substitute for respiratory protection when it is needed.
Put, the only time someone should wear a face shield is in addition to wearing a cloth face covering. Admittedly, this news will likely be discouraging for folks who prefer the comfort that face shields provide relative to masks. Still, the grim reality is that the number of new coronavirus cases is still on the rise, and strictly adhering to CDC guidelines is more crucial than ever.