Lower humidity in winter could boost Covid-19 spread

The Japanese supercomputer Fugaku, which has been used to model the impact of humidity on virus transmission, has shown that virus particles can spread further in dryer conditions. This suggests that the upcoming winter months could have a higher risk of contagion for Covid-19.

The findings suggest that humidifiers could be used to help limit the spread of infections indoors when ventilation isn’t possible.

In June, Fugaku gained the titled of the world’s fastest supercomputer and has been used extensively during the Covid-19 crisis to identify existing drugs that may be effective at dealing with the virus. Previous studies conducted using Fugaku also demonstrated that plastic face shields are almost totally ineffective at trapping respiratory aerosols, casting doubt on how useful they are as a tool for minimising Covid-19 transmission.

In the new study from research institute Riken and Kobe University, the supercomputer was used to model the emission and flow of virus-like particles from infected people in a variety of indoor environments. It was found that when air humidity dipped below 30 per cent, more than double the amount of aerosolised particles could be detected compared to levels of 60 per cent or higher.

In the model, almost 100 per cent of airborne droplets of less than 5 micrometres in size escaped through plastic visors of the kind often worn by service industry workers.

It has also shown that proper ventilation in Japanese commuter trains can significantly lessen the spread of Covid-19 when coupled with reduced passenger numbers.

After its launch earlier this year, Satoshi Matsuoka, director of the Riken Centre For Computing Sciences, said: “One of the most important missions of Fugaku as Japan’s flagship supercomputer is to protect the well-being of citizens using its massive computing power.”

“To combat the global pandemic of the Covid-19 virus, we will rapidly provide access to the capabilities of Fugaku, leapfrogging its preparation, to accelerate the scientific process of diagnosis, treatment, as well as general prevention of infection spread, to contribute to the early termination of the pandemic”.

The US Centers for Disease Control and Prevention (CDC) revised its guidance this month to warn the pathogen can linger in the air for hours. It has also been demonstrated that Covid-19 can survive on mobile phone displays and banknotes for up to four weeks

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