Face Shields Can't Protect You From Sneeze Vortex Rings, Says Study
Face masks have been a source of debate since the start of the pandemic with some saying it restricts their freedom, while some stating they don't work at all in the first place. Those who are against them have opted for different measures ranging from wearing mesh masks to using face shields only.
Plastic face shields have proved to be especially popular among those since they give more breathing room and allow others to see the wearer's mouth, which can be beneficial in cases where lip-reading is needed.
However, scientists have conducted an experiment and used computers to model the movement of air from a sneeze to see whether plastic face shields work or not, and the findings are rather worrying.
Visualizing a human sneeze
In order to get to the bottom of things, researchers used computer models and visualized the ejection of a human sneeze that is away 3 feet (1 meter) away and the droplets' spread around a face shield, Science Daily reports.
The simulations revealed that "vortex rings" created by the sneeze; which are "donut-shaped vortex" that is made by an immediate ejection of fluid from a circular orifice, per the study author Fujio Akagi; transport infectious particles to the face shield's top and bottom edges immediately.
Don't skip the face mask
This renders the face shields useless and shows that they offer no protection against COVID-19 without the addition of a face mask. If an infected person sneezes without a mask on, researchers say that the person wearing the face shield can also become infected if the timing of the wave of particles matches the time they were breathing in.
Researchers have also published a video that shows how the airflow from a sneeze can make its way up to the inside of a face shield, further emphasizing the importance of a face mask.
This finding is in line with the previous research which also showed wearing face shields alone isn't enough.
The study was published in the journal Physics of Fluids.