Coronavirus loses 90% of its ability to infect within 20 minutes of becoming airborne, a recent study has found. 

The research, carried out by the University of Bristol’s Aerosol Research Centre, also showed that most of this loss in infectivity occurred within the first five minutes of the virus being exhaled into the air.

“People have been focused on poorly ventilated spaces and thinking about airborne transmission over metres or across a room. I’m not saying that doesn’t happen, but I think still the greatest risk of exposure is when you’re close to someone,” Prof Jonathan Reid, director of the centre and the study’s lead author, told The Guardian. 

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The study, which simulates how the virus behaves after exhaling, reaffirms the containment measures focused on curbing short-range transmission. Masks and physical distancing, therefore, remain extremely important. 

“When you move further away, not only is the aerosol diluted down, there’s also less infectious virus because the virus has lost infectivity (as a result of time),” Reid said. 

Researchers also found that the viral particles rapidly lose water and dry out as they leave the moist and carbon dioxide-rich lungs. The pH of the particles increases, eventually causing their ability to infect to fall.  

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The speed at which this procedure takes place, however, depends on the humidity in the air. In areas with humidity levels below 50%, the virus had lost almost half of its infectivity within five seconds. At 90% humidity, the infectivity declined at a reduced pace for the first 20 minutes to nearly 10%, according to The Guardian.

“It means that if I’m meeting friends for lunch in a pub today, the primary [risk] is likely to be me transmitting it to my friends, or my friends transmitting it to me, rather than it being transmitted from someone on the other side of the room,” said Reid. 

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Importantly, the study found that the temperature of the air had no impact on viral infectivity.

The research findings, which are yet to be peer-reviewed, come at an extremely crucial time as the world battles the recent COVID-19 surges caused by the omicron variant.