Research has shown that much of Covid-19’s ability to infect people is lost within 20 minutes of the virus being aired.
The world’s first simulations of how the coronavirus survives in exhaled breath have shown that most of the loss occurs within the first five minutes after droplets are sent into the air.
Researchers at the University of Bristol have developed devices that allow them to create tiny particles containing the virus and levitate them gently between two electrical rings for between five seconds and 20 minutes.
During this process, the temperature, humidity and UV light intensity around the particles are strictly controlled, The Guardian reports.
Three variants, including Alpha, were tested by the team. Experiments with the Omicron variant should begin shortly.
The study, which has not yet been peer-reviewed, showed that virus particles quickly lose water and dry out outside of the lungs, where conditions are high in carbon dioxide.
This disrupts the ability of Covid to infect human cells.
How quickly particles dry out depends on the relative humidity of the ambient air. At concentrations below 50 percent, the virus lost about half of its infectivity within five seconds, and another 19 percent was lost in the next five minutes.
The decrease was more gradual at 90 percent humidity, where 52 percent of the particles remained infectious after five minutes, and dropped to about 10% after 20 minutes, after which there was no difference.
Prof. Jonathan Reid, Director of the Aerosol Research Center at the University of Bristol and lead author of the study, said, “This is the first time anyone has actually been able to simulate what happens to the aerosol during the exhalation process.”
He added, “People have been focusing on poorly ventilated rooms and thinking about air transfers over meters or across a room. I’m not saying that won’t happen, but I think the greatest risk of exposure is still when you’re around ”for someone.
“If you move further away, not only is the aerosol diluted, there are also fewer infectious viruses because the virus has lost its infectivity [as a result of time]. “
However, the temperature of the air made no difference to the infectiousness of Covid.
Prof. Reid said: “It means that if I meet friends for lunch in a pub today, elementary school” [risk] it is likely that I will forward it to my friends or my friends to myself instead of broadcasting it from someone across the room. “
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