Face shields are simple, transparent screens that cover the face and help prevent infectious droplets from entering the eyes, nose and mouth. They are usually worn in conjunction with masks or respirators, blocking splashes and sprays from reaching the face and making it preventing workers from touching their faces.
"Face shields are generally not used alone, but in conjunction with other protective equipment and are therefore classified as adjunctive personal protective equipment," states a 2016 review of face shields by the US National Center for Biotechnology.
"Little research" into face shields
However, the NCBI review added that guidelines for their use and standards for their manufacture vary widely. "Although there are millions of potential users of face shields, guidelines for their use vary between governmental agencies and professional societies and little research is available regarding their efficacy," it said.
But Mike Edmond, a healthcare epidemiologist and physician based in Iowa City, believes that face shields "offer a better solution" than masks.
"The advantages of face shields are their durability allowing them to be worn an indefinite number of times, the ability to easily clean them after use, their comfort, and they prevent the wearer from touching their face," Edmond wrote on his blog.
"We have a product that is reusable, cleanable, covers more of your face, decreases the risk of autoinoculation, and keeps us from burning through our mask supply," he wrote in another post.
"Importantly, they cover all the portals of entry for this virus: the eyes, the nose, and the mouth. Moreover, the supply chain is significantly more diversified than that of face masks, so availability is much greater."