## 3 Results
### Influence of Cabin Seat Inclination on the Transport of Pollutants  
This section examines the impact of seat inclination on the change in the cabin airflow and the transport of pollutants. Figure 8a shows the modeled airflow distribution in a section across the seats of the fourth row, in which seats 4A to 4C were inclined, i.e., in Case 2. As can be seen by comparing Figure 8a with Figure 5a, the inclination of seats 4A to 4C had only a small impact on airflow. However, the uprising flow in front of seats 4A to 4C was weakened somehow, because the trunks of passengers were moved back with the inclined seats and thus there was a larger separating distance between the human bodies and the section. The uprising plume flow decreased with the separating distance from the human bodies. Consequently, the pollutant released at 4B would be better confined in the half cabin with seats A to C. Figure 8b presents the average pollutant concentrations in respiratory zones of the 21 passengers in seats D to E and the comparison between Cases 1 and 2. It is thus not surprising that the concentration in Case 2 was slightly lower than that in Case 1. Figure 8: Airflow and normalized pollutant concentrations with seats 4A to 4C inclined in Case 2:(a) airflow field in a section across the fourth row, (b) average pollutant concentration in respiratory zone of the 21 passengers seated in D to E for the pollutant released from 4B, (c) average pollutant concentrations in respiratory zone of the passengers in each row for the pollutant released from 4B, (d) airflow in the longitudinal section from 3B to 5B. Figure 8c presents the modeled average pollutant concentrations in passengers' respiratory zones of each row between Cases 1 and 2. The seat inclination resulted in an increase of 87% in pollutant concentration in rows 5 to 7, but a decrease of 54% in concentration in rows 1 to 3. This was because there was a smaller separating distance between seats 4A to 4C and seats 5A to 5C. The effect of the seat inclination was somewhat similar to that of positioning the pollutant source to a closer distance with rows 5 to 7, while a longer distance was presented with rows 1 to 3. Figure 9a,b present the modeled flows in two cross-sections when all of the seats A to C were inclined, i.e., in Case 3. The figure shows that some of the flow from the left half cabin crossed the aisle, and went to the right side. This shows that the asymmetric seat layout had clearly led to the asymmetric flow pattern. Consequently, the cross-pollutant transport across the aisle would be enhanced. Figure 9c presents the modeled average pollutant concentration in the respiratory zone of the half cabin opposite to the pollutant source. For the pollutant released from 4B, there was nearly no difference in the pollutant concentrations in the respiratory zone of the 21 seats of D to E. This was because the airflow from the left air supply had suppressed the airflow from the right air supply in the section across the head of 4B, as shown in Figure 9a. This made the pollutant from the right side of the cabin difficult to transmit to the left side of the cabin. However, for the pollutants released from 4E, the seat inclination in Case 3 has resulted in the concentration in the respiratory zone of the 21 seats of A to C increasing by approximately 81%. The major reason was that the flow above seats of 4D to 4E went across the aisle as shown in Figure 9b. Figure 9: Airflow and normalized pollutant concentrations with all of the seats A to C inclined in  
Case 3: (**a**) airflow field in the cross-section across the head of 4B, (**b**) airflow field in the cross-section across the head of 4E, (**c**) average pollutant concentration in respiratory zone of the 21 passengers seated in opposite to the half cabin with pollutant source. Figure 10a shows the modeled airflow distribution in a section across the fourth row with all of the inclined seats, i.e., in Case 4. Since the seat layout was symmetric, the solved airflow was also nearly symmetric.