How can the risk of contracting Covid-19 be minimized in enclosed spaces? This question has been investigated by the Technical University of Central Hesse. Under the leadership of Professors Dr. Henning Schneider and Dr. Keywan Sohrabi from the Giessen Faculty of Health, a research group has investigated which masks are most likely to prevent the spread of the coronavirus in offices, for example.
A cotton mask prevents the spread beyond one and a half meters, reduces the speed of spread and causes the particles to sink quickly. It provides effective protection if the usual distancing rules are observed. FFP masks, which also protect the wearer and have a higher density, also have a good effect. However, the high pressure on the mask during sneezing causes some of the aerosols to escape upwards.
Face shields are an alternative to masks. According to the study, they deflect the aerosol mainly downwards and sideways to the rear. At a distance of more than one and a half meters, they offer good protection.
The combination of face visor and cotton mask performs best. However, the two project managers concede that this is the most strenuous option for the wearer and cannot be expected of anyone over a longer period of time.
Distribution of the aerosol cloud with mask
Distribution of the aerosol cloud without mask with table fan operation
The most unfavorable scenario proved to be the use of a table fan, which is popular in the warm season. Without the protection of a mask and with the window closed, the aerosol cloud spreads throughout the room in just a few seconds.
Source: Technische Hochschule Mittelhessen (THM)
