# Bacteria Filtration Efficiency for Different Types of Protective Face Masks
## 3 Results and Discussion
FPP2 masks showed a significant filtration efficiency, >96%, of all analyzed bacteria. However, they were somewhat ineffective in filtering _Microoccus_ spp. and _S. chromogenes_ but only at location D, where an efficiency of 68% was found. Furthermore, the filtering efficiency of the masks used was also analyzed depending on the location (A, B, C and D), and the results are shown in Figure 3a-c. From Figure 3, it can be seen that the highest oscillations in the filtration efficiency for bacteria depending on the location were exhibited by the single-layer cloth mask (Figure 3a). Slightly lower differences in air filtration by the single-layer cloth mask were achieved for bacterium _A. luoffi_, while the worst efficiency was achieved at location A (31%, and the highest at location B (60%). Meanwhile, the single-layer cloth mask filtering efficiency was very similar at locations B and C (60 and 57%) and locations A and D (31 and 37%), where the mentioned locations did not show statistically significant differences. A similar situation was found in the filtration of _Bacillus_ spp. and _M. luteus_ bacteria, for which the lowest filtration efficiency was found at location A (28 and 6%) and the highest at location D (70% for both bacteria). The filtration efficiency of _M. luteus_ and _Bacillus_ spp, was significantly different between all locations except between locations A and C. _S. haemolyticus_ was filtered with a single-layer cloth mask at an efficiency of 7 (location A) to 58% (location C), representing significant differences between locations. A very similar filtering efficiency was observed for _Corynebacterium_ spp., ranging from 8 (location D) to 52% (location C), but it should be noted that this bacterium was not isolated at locations A and B. _S. chromogenes_ was filtered most efficiently at location A (79%) and least efficiently at location B (29%), with the only evident difference being observed between locations A and B (\(p<0.01\)). Figure 3: \(Cont\). Higher bacterial filtration oscillations were observed in the remaining analyzed bacteria. Thus, _Microococcus_ spp. was filtered with an efficiency of 16 (location D) to 100%  
Figure 3: Differences in bacterial filtration efficiency between locations: kindergarten group A (location A), kindergarten group B (location B), primary school group A (location C), and primary school group B (location D) with the applied (**a**) cloth, (**b**) surgical, and (**c**) filtering facepiece type 2 (FFP2) masks expressed in percentage (%) as compared to the control group. The data are presented as mean values of three determinations with standard deviations. Mean values marked with lowercase letter a represent significant differences between location A and the other locations (locations B, C, and D), lowercase letter b represents significant differences between location B and locations C and D, while lowercase letter c represents significant differences between location C and location D (\(p<0.01\); nonparametric Kruskal–Wallis [multiple comparisons] test). (locations A and B), _S. aureus_ from 47 (location C) to 100% (location B), _S. lentus_ from 15 (location A) to 100% (B), and _S. epidermidis_ from 50 (location C) to 100% (location D). The results of bacterial filtration efficiency of the surgical mask are shown in Figure 3b. Much lower oscillations in filtration efficiency were observed with the surgical mask than with the single-layer cloth mask. The highest range in filtration efficiency was observed for _S. haemolyticus_ from 65 (location C) to 90% (location A) with statistically significant differences between the different locations (_p_ < 0.01). A similar situation was observed with _M. Luteus_ (77% at location D and 98% at location C) and _A. lwoffii_ (75% at location D and 97% at location A). The following are the bacteria for which the surgical mask achieved a filtration efficiency of 100% for at least one of the locations: _Bacillus_ spp. from 67 (location D) to 100% (locations B and C), _Corynebacterium_ spp.