Scientists have found that the key factor for the transmission of the SARS-CoV-2 coronavirus is the rate of evaporation of moisture in the air. This was announced in a press release on EurekAlert !.
The researchers studied the effect of humidity, ambient temperature and wind speed on the spread of the smallest droplets of saliva that contain virus particles. The results of theoretical modeling and hydrodynamic experiments have shown that high temperatures and low relative humidity lead to a high evaporation rate of droplets contaminated with saliva, which significantly reduces the viability of the virus.
However, the distance that droplet clouds travel, as well as their concentration, remain significant even at high temperatures if the relative humidity is also high. Wind speed is another main condition affecting possible changes in the social distancing rule.
These results help explain why the pandemic intensified during July in various densely populated cities around the world that experienced both high temperatures and high relative humidity. They also warn of the possibility of a second wave of the pandemic in the coming fall and winter seasons, when low temperatures and high wind speeds will increase survival and transmission of the airborne virus.