It’s getting increasingly difficult to keep track of all the COVID-19 gear devouring ad space.
After public health officials made up their minds about the utility of masks (please wear them everywhere), the jury was out on the kind of masks that offered the best protection (N-95 and double-layer cotton). Then we all mulled over gloves, sneeze guards, and finally face shields.
Previously, Dr.Anthony Fauci, who has served as the director of the National Institute of Allergy and Infectious Diseases for more than three decades, floated the idea of heavily impacted populations adopting face shields during high-risk scenarios. Though, the immunologist has maintained faith in face masks and social distancing for the entire duration of the pandemic.
A new experiment, indexed in the journal Physics of Fluids determined face shields, and masks with valves offer very little protection with respect to COVID-19.
“Face masks have become increasingly accepted as one of the most effective means for combating the spread of the disease when used in combination with social-distancing and frequent hand-washing,” the authors wrote in the paper’s abstract. “However, there is an increasing trend of people substituting regular cloth or surgical masks with clear plastic face
shields and with masks equipped with exhalation valves. One of the factors driving this increased adoption is improved comfort compared to regular masks.”
To test the efficiency of mask valves and face shields, the researcher’s set up a hollow manikin head, and a cough/sneeze system that is activated via
a pressure impulse applied using a manual pump.
The air capacity of the pump was 500 ml, which mimics the lower end of the total volume expelled during a cough.
Next, they manufactured droplets out of distilled water and glycerin. These were projected through the mouth opening of the manikin and visualized with the help of laser sheets
With these conditions in place, neither face shields nor masks valves proved to be effective at stopping viral droplets.
“The visor initially deflects the expelled droplets downward. However, the aerosolized droplets do not fall to the ground but stay suspended beneath the bottom opening of the shield [Fig. 2(c) (Multimedia view)].
These droplets rise upward after a few seconds since they are warmer than the ambient air owing to the vaporized glycerin–water mixture, and also because they might undergo further evaporation once released into the environment.
Comparability is the most occasioned element in favor of face shields, though Kaitlyn McInnis of Ladders actually preferred a traditional cotton masks after wearing a face shield every day for seven consecutive days.
“Honestly, after wearing a face shield for a week I will admit that I prefer my face mask. I’ve actually come to like my bright pink mask quite a bit—with the right sunglasses I actually feel quite stylish,” McInnis wrote, adding unless you’re traveling on a particularly hot day, face masks are the way to go.
“As students return to schools and universities, some have wondered if it is better to use face shields, as they are more comfortable and easier to wear for longer periods of time,” study lead author Siddhartha Verma, an assistant professor at Florida Atlantic University’s College of Engineering and Computer Science, explained in a statement.
“But what if these shields are not as effective? You would be essentially putting everyone in a tight space with droplets accumulating over time, which could potentially lead to infections.”