Researchers at the University of Bristol Aerosol Research Center have studied how the virus spreads through airborne droplets, The Guardian reports. It showed that the greatest risk of infection occurs when we are near a sick person. 20 minutes after being in the air, the coronavirus loses 90% of its ability to infect, and it is most "exhaled" in the first five minutes. This means that physical distancing and wearing masks remain the most effective means of preventing infection. Ventilation is also helpful, but to a lesser extent.
“It was believed that it was important to have good ventilation, as airborne transmission can occur throughout the room. It may be real, but the greatest risk of infection occurs when you are around someone, said Jonathan Reed, director of the University of Bristol Aerosol Research Center and lead author of the study. - When you move away, the droplets of the virus become less infectious. If I meet with friends for lunch, the main risk is likely to be that I pass the virus on to them or them to me and not to someone in the far corner. This underlines the importance of wearing a mask in situations where people are physically unable to distance themselves".
During the study, scientists developed a device that allowed them to generate virus-containing particles and move them a distance. In fact, they created a model of what happens to the aerosol during exhalation. It turned out that when viral particles leave the relatively moist and carbon-dioxide-rich conditions of the lungs, they quickly lose water and dry out. When the air humidity was less than 50%, as in most rooms, the virus became half as infectious in the first five seconds, and after five minutes it lost another 19% of its ability to infect. At 90% humidity - this happens in the bathroom - the infectivity decreased more slowly: 52% of the particles remained infectious after five minutes, and after 20 minutes they were 10%. At the same time, the air temperature did not affect the infectivity, which contradicts the widespread opinion that the virus is less transmitted at high temperatures.