Research Article
Vehicle Emission Factors for Particulate and Gaseous Pollutants in an Urban Tunnel in Xi’an, China
Figure 4
Weekday-weekend pattern of pollutant emissions. The comparison of weekday and weekend traffic volume (a), PM2.5 (b), CO (c), NOX (d), HC (e), and VOCs (f) during the four sampling periods.
| (a) |
| (b) |
| (c) |
| (d) |
| (e) |
| (f) |