Vehicle Emission Factors for Particulate and Gaseous Pollutants in an Urban Tunnel in Xi’an, China

Table 3

Average EFs (g·veh⁻¹·km⁻¹) during different sampling periods.

Species	Morning	Afternoon	Evening	Night	Range
PM2.5	0.006 ± 0.004	0.005 ± 0.003	0.06 ± 0.004	0.011 ± 0.010	0.001∼0.018
CO	1.042 ± 0.152	1.041 ± 0.472	1.260 ± 0.678	1.243 ± 0.197	0.586∼2.271
NOX	0.122 ± 0.078	0.137 ± 0.067	0.143 ± 0.070	0.236 ± 0.115	0.052∼0.438
HC	0.153 ± 0.066	0.135 ± 0.030	0.213 ± 0.145	0.224 ± 0.101	0.073∼0.379
VOCs	0.265 ± 0.077	0.199 ± 0.050	0.365 ± 0.092	0.607 ± 0.184	0.125∼0.868