How long the coronavirus, behind the current pandemic, survives in exhaled air has been unknown so far.
However, a recent study now shows that it loses 90 per cent of its ability to infect human cells within 20 minutes of becoming airborne.
What is even better news is that much of the virus’ infectivity loss already occurs within a mere few minutes.
Results from a study at the University of Bristol’s Aerosol Research Centre underlined the precautions people need to take in order to avoid getting infected, primarily wearing masks and maintaining social distancing.
What is key to determining infection seems to be how close you get to someone who is already infected.
“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,” The Guardian quotes Prof Jonathan Reid, who headed the study as saying.
“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],” he added.
The study has not yet been peer-reviewed and was carried out before the Omicron variant started to spread, and may therefore not apply to the newer variant, however.
A previous study carried out in the United States showed that infectious virus particles were still found after three hours in a study where the virus was sprayed into rotating sealed vessels that kept the virus airborne.
But these conditions are dissimilar to what occurs when people talk and breathe.
The study conducted by the University of Bristol is closer to what happens when individuals exhale, Prof Reid explained.
The scientists who conducted the study experimented with different temperatures and levels of humidity similar to in outside air, and then placed droplets containing the virus on human cells in Petri dishes to see whether the virus would grow.
In 40 per cent humidity air, which is common in office or restaurant settings, within 5 seconds of release, half of the virus became unable to infect the human cells.
As time went on, the virus continued to lose its infectivity and within 10 minutes the “majority” of the virus was inactivated.
After 20 minutes, around 90 per cent of the virus particles were inactive.
In situations where humidity levels were higher, however, such as those similar to a shower or steam room, the virus stayed stable for a longer time.
The Guardian added that the study would be extended to include the Omicron variant in the weeks to come.
Prof Reid added, “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.” /TISG