#$%^&*AU2020100228A420200326.pdf#####Abstract Filter masks have been known for many years, which are intended to protect users (in private, industry, commerce and rescue workers etc.) from dangerous substances (gases and particles of solid and liquid substances). In general, respiratory protection filters are divided into two main categories, namely particle filters and gas filters. In addition, so-called combination filters, which are supposed to offer protection against gases and particles, are available on the market. The service life of particle filters, which are categorized in three, different classes - namely P1, P2 and P3 -, depends on the pollution of the filter material and duration of wear. Depending on the intended use and type of pollutant etc., different mask types with various filter models are offered to filter harmful and / or hazardous substances from the breathing air, namely respiratory masks with particle filters or particle-filtering half or full masks. Particle-filtering half masks are a mask and filter in one and therefore, no filter can be replaced after use and the entire mask has to be disposed after usage. Particle-filtering half-masks mostly consist entirely of a filter material - such as non-woven fabric - and are held on the user's head with elastic rubber bands and a shapeable nose piece to enable adaptation to the face. These particle-filtering half masks are available with and without an exhalation valve - however, with the latter, the breathing resistance is considerably lower and the air humidity is drained through the valve, which increases comfort. This variant is widely used in the medical field to protect against infections. All of the listed respirators and filters in protection classes P1 and P 2 have in common, that they do not offer effective protection against microorganisms (bacteria, fungi and their spores, viruses, etc.) - only, protection class FFP 3 is able to remove such
