## 3 Results  
The median air temperature of the OR using the RDAC system (20.40 \({}^{\circ}\)C) was significantly higher than that of the OR using the conventional HVAC system (19.68 \({}^{\circ}\)C, \(p\) \(<\) 0.01) and the one using the LDAC system (19.44 \({}^{\circ}\)C, \(p\) \(<\) 0.01) (Table 1). The median indoor RH of the OR using the RDAC system (60.49%) and that of the OR using the LDAC system (60.84%) were significantly lower than that of the OR using the conventional HVAC system (66.73%, \(p\) \(<\) 0.01). The CO\({}_{2}\) concentration of the OR using the LDAC system (421.20 ppm) was significantly higher than that of the OR using the conventional HVAC system (357.51 ppm, \(p\) \(<\) 0.01) and the one using the RDAC system (408.88 ppm, \(p\) = 0.026). The PM\({}_{\geq 0.5}\) concentration of the OR using the conventional HVAC system (101.53 particles/L, \(p\) \(<\) 0.01) and that of the OR using the LDAC system (88.08 particles/L, \(p\) \(<\) 0.01) were significantly higher than that of the OR using the RDAC system (21.33 particles/L). Similar results were found for PM\({}_{10}\), PM\({}_{2.5}\), and PM\({}_{1}\) in the three ORs. The median concentrations of airborne bacteria were 46.34-56.42 colony forming units (CFU)/m\({}^{3}\) in the operating areas and 59.80-112.87 CFU/m\({}^{3}\) in the surrounding areas of the three ORs using the different dehumidification air conditioning systems. No difference in airborne bacterial concentration was observed in the operating or surrounding areas of the three ORs. \begin{table}
\begin{tabular}{l c c c c c c c c c} \hline \hline
**Parameters** & **AC Systems** & \multicolumn{2}{c}{**HVAC System**} & \multicolumn{2}{c}{**LDAC System**} & \multicolumn{2}{c}{**RDAC System**} & \multicolumn{1}{c}{**\(p\) Value**} \\ \cline{2-9}  & Mean & Median & 25–75 percentiles & Mean & Median & 25–75 percentiles & Mean & Median & 25–75 percentiles & \\ \cline{2-9} Temperature, \({}^{\circ}\)C & 19.73 & 19.68 & (19.40–20.01) & 19.44 & 19.44 & (18.74–19.79) \({}^{\dagger}\) & 20.51 & 20.40 & (19.93–20.83) \({}^{\dagger}\) & -0.001 \\ RH, \% & 65.14 & 66.73 & (62.99–67.85) & 59.78 & 60.84 & (59.44–62.68) \({}^{\dagger}\) & 55.90 & 60.49 & (47.96–63.31) \({}^{\dagger}\) & -0.001 \\ CO\({}_{2}\) ppm & 344.90 & 357.51 & (302.29–383.34) & 427.49 & 421.20 & (405.08–440.73) \({}^{\dagger}\) & 412.32 & 408.88 & (401.16–420.46) \({}^{\dagger}\) & -0.001 \\ PM\({}_{30.8}\)particles/L & 161.22 & 101.53 & (31.60–173.89) & 146.00 & 88.08 & (12.71–172.95) & 107.09 & 1.33 & (11.21–48.60) \({}^{\dagger}\) & -0.001 \\ PM\({}_{30.9}\)(m\({}^{3}\)) & 1.31 & 0.58 & (0.28–1.76) & 0.98 & 0.68 & (0.10–1.00) & 0.53 & 0.14 & (0.06–0.33) \({}^{\dagger}\) & -0.001 \\ PM\({}_{35.8}\) ug/m\({}^{3}\) & 0.46 & 0.31 & (0.12–0.56) & 0.35 & 0.33 & (0.07–0.50) & 0.40 & 0.07 & (0.04–0.15) \({}^{\dagger}\) & -0.001 \\ PM\({}_{31}\) ug/m\({}^{3}\) & 0.21 & 0.12 & (0.01–0.20) & 0.15 & 0.13 & (0.01–0.24) & 0.33 & 0.01 & (0–0.02) \({}^{\dagger}\) & -0.001 \\ Airborne bacteria, CFU/m\({}^{3}\) & & & & & & & & & \\ Operating area & 109.71 & 50.75 & (24.98–69.38) & 133.17 & 56.42 & (35.44–110.86) & 50.01 & 38.26 & (32.54–79.90) & 0.671 \\ Surrounding area & 154.13 & 112.87 & (43.73–219.75) & 152.50 & 83.51 & (49.29–121.84) & 104.67 & 59.80 & (45.45–167.43) & 0.887 \\ \hline \hline \multicolumn{9}{l}{\({}^{\dagger}\): compared to HVAC system, \(p<0.01\): 1; compared to LDAC system, \(p<0.05\). HVAC system: heating, ventilating, and air conditioning system: LDAC system: liquid desicant air conditioning system; PDAC system: rotary desicant air conditioning system.} \\ \end{tabular}
\end{table} 
Table 1: Indoor thermal-hygrometric conditions and air quality of the operating rooms with different dehumidification air conditioning systems.