Ever since the COVID-19 pandemic took hold of the world, venturing outdoors without protective face covering is considered a cardinal sin. After face masks, plastic face shields have become the second line of defense for many. However, a Japanese simulation model has found that face shields may be completely ineffective in trapping respiratory aerosols, thereby, questioning their effectiveness as a measure to contain transmission.
According to a model projected by Fugaku, the world's fastest supercomputer, nearly 100 percent of airborne droplets of sizes lower than 5 micrometers managed to escape through face shields of the variety used by people employed in the service industry. A micrometer is one-millionth of a meter.
Ineffectiveness of Face Shields
According to Riken, a government-aided research facility located in the city of Kobe in Japan, nearly half of the bigger droplets measuring around 50 micrometers also escaped into the air despite an individual wearing the plastic visors, reported The Guardian.
Makoto Tsubokura, team leader, Centre for computational science, Riken, explained that the simulation model integrated airflow with the replication of droplets of tens of thousands of sizes—from below 1 micrometer to hundreds of micrometers. He also dissuaded the use of face shields as a replacement for masks.
"Judging from the results of the simulation, unfortunately the effectiveness of face guards in preventing droplets from spreading from an infected person's mouth is limited compared with masks," said Tsubokura. He added that the scenario held true specifically for droplets smaller than 20 micrometers.
Tsubokura also said that tinier aerosol particles were found to get through the gap between the shield and the face. "At the same time, it somehow works for the droplets larger than 50 micrometers," he added.
Set to Become Common Place
With countries gradually recommencing commercial activities to revitalize their struggling economies, face masks and shields are expected to become a normal sight. This holds true especially in the case of industries where person-to-person interactions are significantly higher, such as restaurants and grooming establishments.
Some individuals may not be able to wear face masks. These include children and people who have been advised against the use of masks due to existing respiratory complications. For such cases, Tsubokura suggested that they could use face shields instead. However, this must be done only outdoor. And if worn indoors, it must be in well-ventilated settings.
Fugaku's Role in COVID-19 Research
Fugaku's contribution to COVID-19 research is becoming increasingly valuable. For example, the supercomputer which can carry out over 415 quadrillion computations a second, found the masks manufactured with non-woven fabrics are far more effective in preventing the spread of the disease through droplets when compared to materials such as polyester of cotton.
The supercomputer had also conducted simulations on the spread of respiratory droplets in closed spaces such as train carriages without windows and portioned office spaces. While the 130bn yen (£970m) supercomputer is expected to become fully operational only in 2021, hopes pinned on the machine for COVID-19 solutions are high.
Scientists hope that Fugaku will aid in the identification of ideal treatment options for the disease from approximately 2,000 existing drugs, many of which have not entered the clinical trial stage yet.