New research suggests that talking to a friend while infected with coronavirus could be as risky as coughing near to them.
The study, published as a research article in The Royal Society journal, was conducted to explore the risks posed by large droplets and aerosols emitted by those infected with the virus.
How does coronavirus spread?
Coronavirus can spread in multiple ways, including through droplets emitted when a person speaks, coughs, sneezes or even breathes, explaining why experts believe it to spread more easily indoors in badly ventilated settings.
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For the study, experts developed models to explore transmission via large droplets and aerosols, with results suggesting it takes mere seconds for expelled particles to travel beyond the recommended "safe distance" of two metres between people.
Writing in the journal, Professor Pedro Magalhães de Oliveira (co-author of the study) and colleagues explained how their models took into account factors including the time taken for droplets to settle, the makeup of droplets and the size of droplets.
They also explored infection risk, taking into account viral loads of those infected and the estimated viral load required to cause transmission.
What the team concluded was that it was equally as unsafe to stand, maskless, two metres apart from a person coughing as it was to stand without a mask two metres from someone talking.
They also found that, an hour after an infected person has spoken for 30 seconds, the total aerosol droplets left in the air contain more viral mass than one cough.
In poorly ventilated spaces, this could be enough to cause transmission of the virus.
How likely am I to catch coronavirus?
The chance of catching coronavirus, however, depends on a number of factors - including how much aerosol is breathed in, dependent on mask wearing, whether people are indoors and the level of ventilation.
From their findings, the team created an online calculator which allows you to explore your risk of catching coronavirus from airborne particles depending on factors like the size of a room, number of people in it and the ventilation.
The team warned that the tool was not meant to be an absolute guide to risks of infection, but a theoretical estimate of a person's risk in different scenarios.
The best way to reduce risks, said Prof Oliveira, is distancing, masks, and good ventilation.
“You need masks, you need distancing and you need good ventilation so these particles don’t build up in an indoor space and they are safely removed," he commented.