# Bacteria Filtration Efficiency for Different Types of Protective Face Masks
## 3 Results and Discussion
haemolyticus_, which were found at higher amounts at locations A and C (19% and 20% on average for each bacteria) compared with that of locations B and D (6% and 3%). Furthermore, _Bacillus_ spp., _Microoccus_ spp., and _S. aureus_ were isolated at each location but at a smaller number of colonies (less than 10% of the total number of identified bacterial colonies). Among isolated bacteria, _S. lentius_ was found only at two examined locations A and C, while _C.ynebacterium_ spp. and _S. epidermidis_ were isolated at locations C and D. Although it seems that the location could be the reason for the presence or absence of some bacterial species, we believe that probably the lack of using preventive measures for improving the air quality was the main reason for the variable occurrence of different bacterial strains. _S. chromogenes_ was not isolated only at location C. From the data shown in Tables 2 and 3, it can be seen that the single-layer cloth mask showed a very poor filtering efficiency of _M. luteus_ especially at locations A (6%) and D (20%) as compared to the control group, while significantly higher efficiency (_p_ < 0.01) was observed at locations B (70%) and C (50%). _A. luoffi_ was retained in the single-layer cloth mask by 46% on average, _Bacillus_ spp. by 44%, and _S. haemolyticus_ by 30%. Interestingly, the single-layer cloth mask was effective in filtering _Microoccus_ spp. at locations A and B (100%), while at locations C and D, the efficiency was poor at only 21%. A similar situation was observed for _S. aureus_ at location B with 100% filtering efficiency, while at the other locations, the efficiency was 52%. In general, the surgical masks were found to be effective in retaining most bacteria  
\begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline \multirow{2}{*}{**Bacteria/ Treatment**} & \multicolumn{6}{c}{**Location C**} & \multicolumn{6}{c}{**Location D**} \\ \cline{2-9}  & **Control** & **Cloth Mask** & **Surgical Mask** & **FFP2 Mask** & **Control** & **Cloth Mask** & **Surgical Mask** & **FFP2 Mask** \\ \hline _Acinetobacter luoffi_ & 52.33 & 22.33 \({}^{\text{A}}\) & 2.33 \({}^{\text{A}}\) & 0.00 \({}^{\text{A},\text{b}}\) & 44.67 & 28.00 \({}^{\text{A}}\) & 11.00 \({}^{\text{A},\text{a}}\) & 2.66 \({}^{\text{A},\text{ab}}\) \\  & (\(\pm\)3.51) & (\(\pm\)1.53) & (\(\pm\)0.58) & (\(\pm\)0.00) & (\(\pm\)3.06) & (\(\pm\)2.65) & (\(\pm\)1.00) & (\(\pm\)1.15) \\ _Bacillus_ spp. & 8.67 & 6.33 \({}^{\text{A}}\) & 0.00 \({}^{\text{A},\text{a}}\) & 0.00 \({}^{\text{A},\text{a}}\) & 7.00 & 3.33 \({}^{\text{A}}\) & 2.33 \({}^{\text{A}}\) & 0.00 \({}^{\text{A},\text{ab}}\) \\  & (\(\pm\)0.58) & (\(\pm\)0.58) & (\(\pm\)0.00) & (\(\pm\)0.00) & (\(\pm\)0.00) & (\(\pm\)0.58) & (\(\pm\)0.58) & (\(\pm\)0.00) \\  & 10.33 & 5.00 \({}^{\text{A}}\) & 0.00 \({}^{\text{A},\text{a}}\) & 0.00 \({}^{\text{A},\text{a}}\) & 8.33 & 7.67 & 3.33 \({}^{\text{A}}\) & 0.00 \({}^{\text{A},\text{ab}}\) \\  & (\(\pm\)1.53) & (\(\pm\)1.00) & (\(\pm\)0.00) & (\(\pm\)0.00) & (\(\pm\)1.53) & (\(\pm\)0.58) & (\(\pm\)0.58) & (\(\pm\)0.00) \\ _Microococcus_ & 101.67 & 51.00 \({}^{\text{A}}\) & 2.00 \({}^{\text{A},\text{a}}\) & 2.00 \({}^{\text{A},\text{a}}\) & 453.00 & 361.00 \({}^{\text{A}}\) & 104.00 \({}^{\text{A},\text{a}}\) & 6.33 \({}^{\text{A},\text{ab}}\) \\ _Inteus_ & (\(\pm\)6.51) & (\(\pm\)3.00) & (\(\pm\)0.00) & (\(\pm\)0.00) & (\(\pm\)2.40) & (\(\pm\)2.193) & (\(\pm\)16.70) & (\(\pm\)0.58) \\ _Microococcus_ spp. & 9.33 & 7.00 & 1.33 \({}^{\text{A}}\) & 0.00 \({}^{\text{A},\text{ab}}\) & 6.33 & 5.33 & 2.00 \({}^{\text{A},\text{a}}\) & 2.00 \({}^{\text{A},\text{a}}\) \\  & (\(\pm\)1.15) & (\(\pm\)1.00) & (\(\pm\)0.58) & (\(\pm\)0.00) & (\(\pm\)0.58) & (\(\pm\)0.58) & (\(\pm\)0.00) &(over 90%) except for _S. chromogenes_ and _S. haemolyticus_ at location B, for which the efficacy was only 50 and 78%, respectively. Furthermore, at location D, the filtration efficiency of the surgical mask was lower and ranged from 60 to 67% for _Corynebacterium_ spp., _Bacillus_ spp., and _S. haemolyticus_.