A technical contradiction arises when within a system one parameter improves thus automatically causing another one to worsen. In a situation like this, instead of a usual acceptance of compromise which leads to optimization of a solution for a newly founded problem, in inventology we implement the process of idealisation. The experimental part of this study comprises comparative examination of NaCl aerosol leakage, as a simulator of biological agents, into the epidemiological anti-microbe masks EM1 and EM2, with the aim of determining physiological suitability of EM1 and EM2 and the resistance that arises when inhaling NaCl aerosol was measured at the flows of 95dm 3 /min. It was experimentally proved that impregnation of silver nanoparticles onto the inner filtrating layer of EM2 contributes to the increase of its efficiency, and mathematical modelling helped calculate the realistic increase of this means.

The flow of air and aerosol particles through the filtering half masks material depends on the structure porosity. It is very difficult to determine the behaviour of the filtering material during the process of extraction and retention of aerosols. The samples of five filtering half mask models were used in this investigation. Dynamics of the aerosol filtration through the filtering materials was tested using a method for testing the leakage of aerosol particles through the filtering material and a method for testing the inhalation resistance of filtering material, both specified in the SRPS EN 149:2013. Recording of the structural changes in the samples of the tested materials was carried out by the technique of scanning electron microscopy. The experiments showed a deviation of the results in relation to the theory of filtration the finely dispersed submicron sized particles. It was concluded that the aerosol leakage through the filtering half masks and their resistance to aerosol flow change depend on the aerosol flow rates and the on filtration process duration, as a direct consequence of the newly-made changes in the structure of the filtering material and due to reversibility effect between the filtration process and the changes in the filtering material.

The results of comparative experimental testing of different filtering masks are presented in this study. Some of the most important functional properties have been tested on available models of Italian, French, British, Canadian, Swiss, American, and three models of Serbian military protective masks (M3 of the latest generation, as well as M2, and M2FV models of the previous generation). The mask models have been tested on protection factor, dynamic resistance of the exhaust valve and its static permeability, the overall inhalation resistance of protective masks, field of view and optical properties, by standardized testing methods. Based on the experimental results obtained, it can be concluded that the Serbian mask M3 is approximately at the same quality level as tested foreign masks, and above Serbian protective masks of the previous generation marked as M2F and M2FV.

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