## 3 Results and Discussion
### Field Survey Results and Analysis
#### 3.2.1 Physical test results and analysis
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Site** & \begin{tabular}{c} **Test** \\ **Point** \\ **Number** \\ \end{tabular} & \begin{tabular}{c} **Temperature** \\ **(°C)** \\ \end{tabular} & \begin{tabular}{c} **Humidity** \\ **(\%)** \\ \end{tabular} & \begin{tabular}{c} **Illuminance** \\ **(\%)** \\ \end{tabular} & \begin{tabular}{c} **Air** \\ **Velocity** \\ **(m/s)** \\ \end{tabular} & \begin{tabular}{c} **PM2.5** \\ **(m/s)** \\ \end{tabular} & \begin{tabular}{c} **PM10** \\ **(m/s)** \\ \end{tabular} & \
\begin{tabular}{c} **HCHO** \\ \end{tabular} &
\begin{tabular}{c} **CO\({}_{2}\)** \\ \end{tabular} \\ \hline W2 & Tp3 & 30.6 & 62.1 & 2.5 & 0.117 & 54.8 & 76.3 & 0.055 & 981.9 \\ \hline W3 & Tp7 & 30.4 & 65.2 & 24.4 & 0.144 & 73.5 & 102.8 & 0.126 & 1308.2 \\ \hline W5 & Tp14 & 28.9 & 52.9 & 147.9 & 0600 & 32.2 & 45.0 & 0.047 & 928.9 \\ \hline \hline \end{tabular} Note: The data in the grey background indicate that it is beyond comfortable zone.  
\end{table} 
Table 6: Average values for the physical test results from the tube entrance (connection to a building). Figure 7: Box diagram of the physical test results from the tube entrance (connection to building). kinds of wind that had large temperature and direction differences. They expressed great discomfort and likely were experiencing threats to their health. The physical environment test at the station hall focused on Beijing subway line #1, and included three test points. As can be seen from Figure 9, the environment temperature in the station hall was significantly higher than the comfort zone and 5 to 6 \({}^{\circ}\)C higher than the outdoor temperature at that time. The humidity in the station hall was also relatively high, but the light environment basically met the national standard. Due to a large number of people flowing through the middle of the station hall and the relatively longer tube lengths (130 m, 190 m, and 160 m), the CO\({}_{2}\) concentrations at the three points were correspondingly higher. The peak concentration of CO\({}_{2}\) at the tp6 measuring point reached 1833 ppm. Tp12 was located at a point with a smaller people flow rate, so its CO\({}_{2}\) concentration stayed within the standard range. However, due to the impact of the subway piston wind, there was a high level of PM pollution in the subway tunnel that was brought into the entrance hall, with a peak concentration of 160 g/m\({}^{3}\). Compared with the outdoor concentration 74.6 g/m\({}^{3}\), this was two times the outdoor concentration at that time. Thus, it can be seen that a large number of people were gathered at the station and hall levels, resulting in a higher concentration of CO\({}_{2}\). The station hall layer was directly connected to the train platform and had a higher PM concentration due to the influence of the piston wind from the subway. In summary, influenced by the space size and flow rate, the physical environment of the hall at all stations was the worst, which is reflected in the high temperature and humidity, and poor air quality. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \multirow{2}{*}{**Site No.**} & **Test Point** & **Temperature (\({}^{\circ}\)C)** & **Humidity (\%)** & **Illuminance (Lux)** & **Air Velocity (m/s)** & **PM2.5** & **PM10** & **HCHO** & **CO\({}_{2}\)** \\ \hline W1 & Tp2 & 30.8 & 50.0 & 154 & 0.365 & 53.5 & 75.9 & 0.019 & 688.4 \\ \hline W2 & Tp5 & 28.6 & 66.0 & 32.5 & 0.859 & 52.7 & 73.6 & 0.019 & 840.5 \\ \hline W4 & Tp10 & 31.3 & 68.3 & 107.3 & 1.73 & 107.6 & 151.1 & 0.021 & 920.8 \\ \hline W5 & Tp13 & 31.1 & 70.0 & 91.2 & 0.683 & 149.2 & 201.7 & 0.026 & 802.4 \\ \hline \end{tabular} Note: The data in the grey background indicate that it is beyond comfortable zone.  
\end{table} 
Table 7: Average values for the physical test results from the tube entrance (connection to subway). Figure 8: Box diagram of the physical test results at the tube entrance (connection to subway).