An international team of scientists has shown that popular measures against the spread of the SARS-CoV-2 coronavirus – social distancing and wearing masks – are not effective enough to contain the pandemic, although they do reduce the risk of infection. The researchers presented their findings in an article published in the International Journal of Multiphase Flow.
Experts have developed an improved model for the spread of aerosols in the form of droplets with infection in the air. The current models, based on measurements from the 1930s to 1940s, are outdated and do not account for microscopic particles. They assume that heavy droplets settle quickly, while small ones move almost horizontally, but evaporate quickly. However, even when the droplet evaporates, an aerosol particle that can contain the virus remains.
It turned out that a particle with a diameter of 10 micrometers takes 15 minutes to fall to the ground. As a result, even those people who follow the rules of social distancing can come into contact with the virus, for example, in an elevator, which was previously infected. Rooms with high humidity and poor ventilation are especially dangerous in this sense.
However, scientists emphasize that wearing masks and social distancing should not be seen as useless measures. Masks prevent large droplets from spreading, which may contain large doses of the virus, and social distancing reduces the chance of infection. However, neither one nor the other provides guaranteed security.
