## 3 Results  
Table 1 shows the results of microbiological contamination of 10 different offices located in buildings with centralized systems for ventilation. The mean values were higher for mesophilic bacteria during the air conditioning phase compared to heating (\(p=0.034\)) and during simple ventilation compared to heating (\(p=0.023\)). The contamination of psychrophilic bacteria was greater during simple ventilation compared to air conditioning (\(p=0.016\)) and to heating (\(p=0.032\)). The mean values of CFU/m\({}^{3}\) for the fungi were not significantly different during the different periods of air treatment. Although the average contamination was low, there were high maximum values of CFU/m\({}^{3}\) for mesophilic bacteria in the periods of air conditioning and simple ventilation and for psychrophilic bacteria during simple ventilation. The calculation of GIMC/m\({}^{3}\) confirmed the presence of higher values of contamination during conditioning (\(p=0.01\)) and simple ventilation (\(p=0.01\)) compared to heating. The average value of IMC during heating amounted to 7.30 and was higher than the values of the other modes of operation, corresponding to 0.80 during the simple ventilation (\(p=0.04\)) and 1.60 during air conditioning (Table 2). The data regarding the microbiological contamination found in 10 different gyms with centralized ventilation systems are summarized in Table 3. The results show highest mean values for mycetic contamination during the air conditioning phase compared to simple ventilation (\(p=0.04\)) and heating (\(p=0.01\)). As regards bacteria, the average contamination values for psychrophilic bacteria were \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Functioning Modes**} & \multirow{2}{*}{**N**} & **Mesophilic Bacteria** & **Psychrophilic Bacteria** & **Fungal Count** \\  & & **CFU/m\({}^{3}\)** & & **CFU/m\({}^{3}\)** & **CFU/m\({}^{3}\)** \\ \hline \multirow{3}{*}{Heating Simple ventilation Air Conditioning} & M \(\pm\) SD & Min-max & M \(\pm\) SD & Min-max & M \(\pm\) SD & Min-max \\  & 10 & 191.20 \(\pm\) 144.53 & 8-450 & 176.70 \(\pm\) 117.21 & 7.965 & 136.00 \(\pm\) 32.80 & 22-654 \\  & 10 & 667.60 \(\pm\) 1062.60 & 6-2500 & 761.90 \(\pm\) 1519.7 & 10-5000 & 131.50 \(\pm\) 72.30 & 5-190 \\  & 10 & 1089.70 \(\pm\) 2392.20 & 19-7800 & 495.60 \(\pm\) 307.20 & 76-860 & 119.60 \(\pm\) 48.84 & 28-199 \\ \hline \hline \end{tabular} The number of samples (N), mean (M), standard deviation (SD), and range of values are indicated for each sampling period. CFU: colony-forming units.  
\end{table} 
Table 1: Total microbial concentrations measured in the offices during heating, air conditioning, and simple ventilation. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Functioning Modes**} & \multirow{2}{*}{**N**} & **GIMC/m\({}^{3}\)** & **IMC** \\ \hline \multirow{3}{*}{Heating Simple ventilation Air Conditioning} & M \(\pm\) SD & Min-max & M \(\pm\) SD & Min-max \\  & 10 & 503.90 \(\pm\) 282.22 & 124–1111 & 7.30 \(\pm\) 20.03 & 0.20–64.30 \\  & 10 & 1561.00 \(\pm\) 3154.80 & 21–10.450 & 0.80 \(\pm\) 0.40 & 0.10–1.30 \\  & 10 & 1704.90 \(\pm\) 2537.57 & 229–8720 & 1.60 \(\pm\) 2.67 & 0.02–9.10 \\ \hline \hline \end{tabular} The number of samples (N), mean (M), standard deviation (SD), the range of values are indicated for each sampling period.  
\end{table} 
Table 2: Global index of microbial contamination per cubic meter (GIMC/m\({}^{3}\)) and index of mesophilic bacterial contamination (IMC) measured in offices during heating, air conditioning and simple ventilation. superior to those for mesophilic bacteria in the three air treatment modalities and were significantly different during conditioning (\(p=0.02\)). There was a notable increase in fungal count when the central heating was switched off. In fact, the highest maximum values of CFU/m\({}^{3}\) were found for fungi during simple ventilation and conditioning, in contrast to what observed for bacteria (\(p=0.016\)).