# Static Factors in Sitting Comfort: Seat Foam Properties, Temperature, and Contact Pressure
## 3 Experimental Campaign
### Experiment 2: The Influence of Seat-Passenger Interface Pressure and Temperature
#### 3.3.1 Influence of Anthropometric Characteristics  
The three subjects performed the experiments at the current AP train seats (comfort and standard) to evaluate the influence of users' anthropometric characteristics on perceived comfort. Pressure results regarding the comfort seat can be found in Table 7.  
By observing the results, both maximum and mean pressures demonstrated values above the maximum, 32 mmHg. Some authors defined this threshold as the trigger for developing discomfort and increasing the risk of health consequences, particularly for longer sitting exposures [2; 16; 28; 30; 31]. Those pressures and contact areas revealed an increasing tendency related to the subject's weight. Moreover, pressure peaks were obtained at the ischial tuberosities regions (R1 and L1); S2 (57 mmHg) and S3 (65 mmHg) are even above the pressure threshold (43.50 mmHg) stated for that specific region [15; 29]. Additionally, [PERSON] et al. [15] and [PERSON] et al. [29] suggested that the mean pressure should never exceed 37.75 mmHg elsewhere in the sitting region, which is true for the present case. S1 and S3, the lightest and heaviest pressure profiles, are illustrated in Figure 9.  
As observed, the two subjects demonstrated different pressure profiles, being the S3 larger (X direction) and the S1 with a higher length (Y direction). Comparing both contact areas, as expected, the heaviest subject produced a higher contact area than the lightest individual. Table 8 presents the pressure distributions regarding the standard seat. As for the comfort seat, all subjects presented maximum pressures above 32 mmHg for the standard seat as well. Nevertheless, those pressure peak values are slightly inferior to those of the comfort seat. The same decreasing tendency was observed for the mean pressure. This fact can be justified by the highest contact areas promoted by the standard seat. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Sub.**} & \multicolumn{3}{c}{\(P_{max}\) (mmHg)} & \multicolumn{3}{c}{\(P_{avg}\) (mmHg)} & \multirow{2}{*}{**Contact Area**} \\ \cline{2-2} \cline{4-7}  & **R1** & **R2** & **L1** & **L2** & **R1** & **R2** & **L1** & **L2** \\ \hline S1 & 37 & 26 & 29 & 20 & 29 & 20 & 23 & 15 & 1076 \\ \hline S2 & 57 & 18 & 50 & 17 & 46 & 16 & 44 & 14 & 1060 \\ \hline S3 & 41 & 29 & 65 & 27 & 35 & 22 & 58 & 22 & 1339 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Maximum and mean pressure and contact area regarding the current comfort AP seat. Figure 9: Current AP comfort seat pressure profiles, (**a**) S1 subject, (**b**) S3 subject. Regarding the interface temperature, results present the maximum, minimum, and average temperatures, and the difference between maximum and minimum temperatures for the sitting area and for a profile line. Figure 10 shows a 3D thermal image in the course of the experiment. Otherwise, Figure 10 presents the region of interest and a profile line of the seat. The profile line clearly distinguishes between the seat's initial temperature and its increase due to the subject's presence. Regarding the sitting area, similar temperatures were obtained for the difference between maximum and minimum values. This result may indicate that the user's anthropometric characteristics do not influence the temperature increase. The sitting line revealed that subject S1 induced higher temperature differences when compared to the seat's initial temperature. Moreover, the same subject also induced the highest maximum and average temperatures in the sitting area. This is the only female subject, which may justify the results. Therefore, although the passengers' anthropometric features (weight and height) do not impact the temperature, it may be observed that gender is a possible cause of influence. Nevertheless, it should be highlighted that due to the reduced number