A new study conducted by researchers at Florida Atlantic University sheds light on the ineffectiveness of face shields and valved face masks.
Researchers filmed a video to highlight the use of a water and glycerin mixture to depict a cough or sneeze from the mouth or nose of a mannequin.
The simulation was done under two circumstances: one with the mannequin wearing a face shield and another with mannequin wearing a face mask with an exhalation valve.
Siddhartha Verma, Ph.D., a professor at Florida Atlantic University and one of the researchers who contributed to the study, discussed the findings of the study as he explained why face shields and valved masks might not be effective enough to stop smaller droplets.
While the video did confirm masks are effective for larger droplets, it showed smaller droplets were noted to have escaped from the visor.
“The larger droplets, they will get stopped, but the smaller droplets, they follow the air streams very well, so they can basically flow around the visor very easily,” Verma said on ABC New’s “Good Morning America.”
He later added, “When we inhale, the valve basically closes so all of the air gets filtered through the mask material. But during exhalation, the valve opens and nothing needs to go through the mask material. There is free flow of air which is not good if you’re trying to restrict the flow of droplets.”
See Verma’s remarks below:
A new visual experiment from Florida Atlantic University researchers shows why you shouldn't rely on face shields and face masks with valves. @ReeveWill reports. https://t.co/DT0fj3HCZd pic.twitter.com/x8gSK97NI4
— Good Morning America (@GMA) September 2, 2020
The Florida research study follows the Centers for Disease Control and Prevention (CDC)’s warning against substituting face shields for masks.
On its website, the CDC said, “At this time, it is not known if face shields provide any benefit as a source control to protect others from the spray of respiratory particles.”
The agency added that face shields are primarily used for “eye protection for the person wearing it.”
Additionally, the CDC cautioned, “There is currently not enough evidence to support the effectiveness of face shields for source control. Therefore, CDC does not currently recommend use of face shields as a substitute for masks.”
“That was the main motivation for the study,” Verma said. “For people to see for themselves what really happens to these tiny droplets when you use a face shield.”
As the study aims to raise awareness about the use of face shields, the United States has reported more than 6.2 million confirmed COVID-19 cases and 189,228 deaths.
