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Further Review: Chiefs Coach Andy Reid and the Incredibly Foggy (and So Wrong) Face Shield

September 22, 2020

No NFL head coach is trying harder than the Kansas City Chiefs’ Andy Reid to comply with league rules about covering faces during games this COVID-19 season, even as several other coaches have been fined $100,000 each for violations.

Reid, almost comically, adopted a face shield that fogged up during the Chiefs’ first game. He has solved the fogging-up problem, but there’s a bigger problem: A face shield is a poor substitute for a conventional cloth mask.

Already, the Centers for Disease Control and Prevention has recommended avoiding both face shields and masks with exhalation valves. Positioned away from the face, with gaps along the edges, face shields cannot contain droplets if the user coughs or sneezes. Likewise, the face shield cannot prevent airborne particles from being inhaled by the wearer.

Earlier this month, researchers at Florida Atlantic University’s College of Engineering and Computer Science used qualitative visualizations that showed how poorly face shields perform in stopping the spread of aerosol-size droplets.

The study, published in the journal Physics of Fluids, created a synthetic fog with distilled water and glycerin, illuminated by a laser light sheet. This fog was expelled from a mannequin’s mouth, simulating a cough or sneeze. The researchers found that the face shields only blocked the cough-jet’s initial forward trajectory, allowing droplets to escape beyond the edges. (Similar tests with a N95-rated mask with a valve showed droplets escaped unfiltered through the valve.)

Some advice for Andy Reid and all the other face-shield lovers around the country: Wearing a face shield over a mask is OK, because it protects your eyes and prevents you from touching your face. But a face shield alone doesn’t offer enough protection. Always use a conventional cloth mask, as recommended by the CDC.

“Wearing a mask and physical distancing has played a very significant role in mitigating and decreasing the surge of this infection,” says Dr. Faiqa Cheema, a Hartford HealthCare infectious disease specialist.