Bhubaneswar: A face shield is a clear plastic barrier that can protect your eyes and discourage you from accidentally touching your face. It can be used in addition to a face mask, say experts citing the lack of research on its effectiveness.
The major concern with a face shield is that it doesn’t tightly cover the face. The research isn’t clear if virus droplets can travel through the gaps at the sides.
A study by the Israel Institute for Biological Research used a “cough source” just one foot above or below the mask of a mannequin, but 60 cm away horizontally. The mannequin’s face was spattered with droplets that spilled in from the sides of the visor. This way, the visor was found to be only 45 percent effective at blocking the droplets. For droplets sprayed directly onto the face, the shield was found to be up to ten times more than a mask.
Similarly, a test carried out by the US National Institute for Occupational Safety and Health in Morgantown with aerosols, found that while a face shield blocks 96 percent of large cough droplets, it only can block 68 percent of smaller cough aerosols.
According to the US Centre for Disease Control and Prevention (CDC), the best face shields are those that wrap around the sides and bottom of the face.
The CDC doesn’t recommend wearing a face shield without a mask. It also recommends cleaning a reusable face shield after each use. It points out that one should clean their hands before taking it off, just like in the case of a mask. Most experts recommend wearing it in addition to a mask.
So, can it be used instead of a mask? No. With a mask? Yes!
