That confirms “that the virus is mainly transmissible over short distances,” and goes against the idea that humidifiers would help fight corona infections, write Jonathan Reid and colleagues at the Aerosols Research Institute at the University of Bristol in their still raw report. research report. “Dry air can help reduce exposure.”
Moreover, the invention detracts from the importance of ventilation. “Many people are focused on poorly ventilated areas and think that the virus travels meters through the air,” Reid said. in the British press. “I’m not saying this doesn’t happen at all, but I think the biggest risk of exposure is when you’re close to someone. If you stand further away, not only are the aerosols diluted, but there is also less infectious virus, because the virus loses its infectivity over time.’
Apres ski bars
It is clear that the virus can sometimes spread through the air over great distances. Already in the first outbreaks in après-ski bars, meeting rooms and choir rehearsals, the virus appeared to accumulate and also infect people from a distance. This is why almost all health authorities now advise taking ventilation into account.
But exactly how often and under what circumstances the virus can start to cloud around is still a mystery. Physicists point to the behavior of exhaled and coughed-out droplets, which dry up slightly in dry rooms, become lighter and thus float longer. But virologists prefer to point out tests in which they tried to harvest an effective infectious virus close to the mouth of corona patients: that is very difficult.
This is probably because many virus particles do not survive the transition from the moist, CO2-rich lungs to the outside air, Reid now says. The British investigated this with a new device: a kind of cookie jar, in which tiny droplets (aerosols) are kept floating in an electric field, while the researchers adjust the conditions.
classroom
After about five minutes, the virus has largely lost its ability to infect culture cells, it shows. In the dry conditions of an office or classroom, the virus loses 90 percent of its infectiousness within 20 minutes. And, remarkably, the temperature does not matter, which goes against the idea that the coronavirus survives better in coolness.
On the other hand, be careful in damp areas, such as bathrooms, steam saunas or sweaty, poorly ventilated clubs. The virus seems to survive better there after exhalation. Physicists point out that droplets become heavy more quickly at high humidity and fall to the ground.
‘An interesting article’, responds virologist Sander Autumn (Erasmus MC) when asked. Although it is certainly not the last word as far as he is concerned: ‘For example, I wonder what the influence of the electric field with which the particles are kept in the air is on the stability of the virus.’ Moreover, the laboratory research remains, he recalls: for example, Reid did not work with drops of throat mucus but with water.
In The Guardian warns virologist Stephen Griffin meanwhile, the new find should not be seen as a plea against ventilation. ‘Aerosols will quickly fill up interior spaces in the absence of good ventilation. And the infected individual will continue to replenish the virus level.”