Filters are made of polypropylene fibres, which is one of the most common plastics, used in the food industry. The fibres are very fine and entwined so that even very small particles trap the pores between them. In particular, for the material being sold, the particle capture efficiency of virus size is at least 81%. It does not protect 100%, which is not even possible in a cloth facial mask. Its main weakness is the imperfect sealing on the face. An effective, ie denser filter, for example two layers of what you buy, has a capture efficiency close to 100%, but it would not be possible to breathe properly through it and the air would be sucked in mainly by leaks. So a fabric facial mask filter must be a compromise between good breathability and good efficiency. In any case, it reduces the risk of transmission of the infection, because it protects in both directions – the wearer and his surroundings. And when you encounter an infection, at the very least, it will reduce the amount of viruses you inhale. This can be crucial for the further course of the disease, whether it is mild or complicated.

The filter is used once and after removal we recommend sterilizing the whole facial mask with the filter in boiling water, as they may be contaminated. The filter must then be removed from the mask and discarded. It is then necessary to insert a new filter into the cloth mask. There is no point in trying to sterilize and reuse the filters. Sterilization reduces the efficiency of the filter and the energy intensity of sterilization would be higher than the production of one filter, which consists of about one gram of polypropylene.