In their calculations of the risk of contamination, the team took into account a number of factors that were not previously included in similar studies. For example, scientists have studied how incorrect contact of masks reduces protection and how this can be prevented.
“FFP2 or N95 mask materials as well as some surgical masks filter the air very effectively,” Bagheri said. “Then the risk of contamination is dominated by air entering and escaping from the edges of the mask.” This happens when the edge of the mask is not close to the face.
In extensive experiments, Bagheri, Bodenschatz and their team measured the size and number of particles that would flow along the edges of the mask if they were not positioned correctly.
“The mask adapts very well to the shape of the face if you fold the metal strip into a round ‘W’ before wearing it,” said Bodenschatz. “Then the infectious aerosol particles will no longer be able to get past the mask and your glasses will no longer evaporate.”
The team also took into account the fact that the droplets that people spread when they breathe or talk become drier in the air and therefore lighter. This means that they stay in the air longer, but also have a greater concentration of virus than droplets of equal size immediately after they are released. When inhaled, the particles absorb water and change their size, facilitating settling in the respiratory tract.
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