COVID Is 90% Less Infectious After 20 Minutes In Air, Claims First Of Its Kind Study
A new study has once again reiterated the importance of wearing face masks and maintaining social distancing to fight the spread of COVID-19.
The study published by the University of Bristol¡¯s Aerosol Research Centre has said that COVID-19 becomes 90% less contagious within 20 minutes of going airborne and loses most of its potential to infect during the first five minutes.
According to The Guardian, this was the world¡¯s first simulation-based study of how the virus survives in exhaled air.
What the study says
¡°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 University of Bristol¡¯s Aerosol Research Centre and the study¡¯s lead author told The Guardian.
¡°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.
Until now, our assumptions about how long the virus survives in tiny airborne droplets have been based on studies that involved spraying virus into sealed vessels called Goldberg drums, which rotate to keep the droplets airborne. Using this method, US researchers found that infectious virus could still be detected after three hours. Yet such experiments do not accurately replicate what happens when we cough or breathe.
Instead, researchers from the University of Bristol developed apparatus that allowed them to generate any number of tiny, virus-containing particles and gently levitate them between two electric rings for anywhere between five seconds to 20 minutes, while tightly controlling the temperature, humidity and UV light intensity of their surroundings. ¡°This is the first time anyone has been able to actually simulate what happens to the aerosol during the exhalation process,¡± Reid said.
The?study, which has not yet been peer-reviewed, suggested that as the viral particles leave the relatively moist and carbon dioxide-rich conditions of the lungs, they rapidly lose water and dry out, while the transition to lower levels of carbon dioxide is associated with a rapid increase in pH. Both of these factors disrupt the virus¡¯s ability to infect human cells, but the speed at which the particles dry out varies according to the relative humidity of the surrounding air.
The findings support what epidemiologists have been observing on the ground, said Dr Julian Tang, a clinical virologist at the University of Leicester, adding that ¡°masks are very effective ¡ as well as social distancing. Improved ventilation will also help ¨C particularly if this is close to the source.¡±
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