Face shields are commonly seen inside the hospitals, but as the pandemic drags on, the public is now advised to wear one to prevent the spread of coronavirus. It has become an essential requirement as businesses start to reopen, such as shops and beauty salons.
But do they actually work?
A simulation conducted by the world's fastest supercomputer in Japan cast doubt on the effectiveness of plastic face shields.
Read: Are Face Masks Effective Against COVID-19? The Pros and the Cons
Face Shields Ineffective at Trapping Aerosols
The world's fastest supercomputer, Fugaku, was used to test the effectiveness of face shields in preventing coronavirus from spreading. They found out that nearly 100% of airborne droplets of less than five micrometers in size escaped through the plastic face shields of the kind that people in service industries commonly use.
To put it in perspective, one micrometer is the one-millionth of a meter.
Additionally, a government-backed research institute in the western city of Kobe, Riken, said that about 50% of the larger droplets measuring 50 micrometers find themselves mixed into the air.
Recently, senior scientists in the UK have criticized their government for stressing the importance of handwashing but placing insufficient emphasis on aerosol transmission and ventilation, unlike the Japanese authorities who have included it in their outline public health guidelines throughout the pandemic.
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Face Shields Not an Alternative To Face Masks
The simulation is a combination of airflow and the reproduction of thousands of particles of various sizes from 1 micrometer to several hundred micrometers, said Makoto Tsubokura, who is a team leader Riken's center.
He warns the public that face shields are no alternative to wearing masks based on the results of their simulation. He added that the effectiveness of face shields in preventing droplets from an infected person to transferring to a healthy individual is limited compared to wearing masks.
Tsubokura said that this is especially true to droplets that are 20 micrometers, especially all smaller aerosol droplets that can escape through the gap between the face and the face shield. At the same time, face shields somehow work for larger droplets measuring 50 micrometers.
He suggested that those people who are advised not to wear masks, such as those with underlying respiratory problems and children, could wear face shields instead when outdoors and indoor settings with proper ventilation.
Moreover, Fugaku, the supercomputer, recently found that non-woven fabric face masks can effectively block the spread of COVID-19 through airborne droplets than cotton or polyester made masks.
Fugaku also ran simulations n how respiratory droplets spread when inside offices and trains. Although the supercomputer will not be operational until next year, experts are hoping to use it to identify treatments for COVID-19 from over 2,000 available drugs, including those that have yet to reach the clinical trial stage.
Read More: Japanese Researchers Developed Computer Model Proving Face Masks Save Lives by Up to 70%
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