Federal Minister of Justice Marco Buschmann questioned last Saturday (June 18) whether wearing masks indoors would provide sufficient protection against infection with the Sars-CoV-2 coronavirus, so that a legal requirement to wear them is justified. Literally he said in an interview with the newspaper Rheinische Post: “If the state wants to prescribe masks, for example indoors, it must be evidence-based and proportionate. We will discuss whether this is the case when all reports are available.” Since then, the minister has been sharply criticized from various sides. Because at least there is no lack of evidence, i.e. proof that masks protect their wearers from infections.
One of the most thorough and most cited studies on the subject to date comes from the Max Planck Institute for Dynamics and Self-Organization in Göttingen. The research facility has specialized in the modeling and simulation of complex physical systems. These include cloud formation in the atmosphere or the interaction of nerve impulses in the brain, but also various aspects of the dynamics of the spread of pathogens such as the corona virus.
The team led by researchers Gholamhossein Bagheri and Eberhard Bodenschatz wanted to know to what extent masks can filter out viruses from the exhaled air of infected people, i.e. prevent these people from unintentionally becoming a danger to others. To do this, the scientists used physical experiments to simulate how particles (aerosols) the size of Sars-CoV-2 behave in the room air when they are exhaled by infected people without a mask. The researchers then examined how well different types of masks (simple surgical masks or denser FFP2 masks) can filter these aerosols out of the breathing air. The researchers also observed how the protective effect of the masks changes if they are worn incorrectly and, for example, breathing air can continue to flow out unfiltered through gaps in the nose or on the sides.
The main result: “The membranes of FFP2 or KN95 masks, but also of some medical masks, filter extremely effectively,” says first author Bagheri. With poorly fitting masks, the protection is lower because virus particles can continue to escape through the gaps. But there is still a positive effect compared to the option of not wearing a mask at all. A comparison of different mask types with each other showed: FFP2 masks offer 75 times better protection than a surgical mask if both fit correctly.