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

Table 4

A comparison of the EFs (g·veh⁻¹·km⁻¹) among this study and other studies.

Tunnel	City/Country	Test year	Average vehicle speed (km·h^−1)	Vehicle type	PM2.5	CO	NOX	HC	VOCs	References
Clem Jones Tunnel	Brisbane, Australia	2014	80	Light-duty	0.015 ± 0.002	1.370 ± 0.079	0.519 ± 0.036			[35]
Zhujiang Tunnel	Guangzhou, China	2014	20–47	Total fleet		3.096 ± 0.680	1.286 ± 0.204	0.448 ± 0.038		[32]
Yingpan Road Tunnel	Changsha, China	2013	30	97.3% gasoline		0.745 ± 0.561∼6.050 ± 5.940	0.121 ± 0.022∼0.818 ± 0.755			[33]
Van Nuys Tunnel	Nuys, California	2010	42.4	97% gasoline		21.300 ± 3.700	3.000 ± 0.600	2.300 ± 0.300		[39]
Loma Larga Tunnel	Monterrey, Mexico	2009	42–76	97% gasoline	Uphill: 0.013 ± 0.006	11.800 ± 3.880	0.130 ± 0.100	1.540 ± 0.080		[29]
Xianyue Mountain Tunnel	Xiamen, China	2005	47.45	Car		14.200	2.210	0.670		[37]
				Taxi		19.700	4.150	0.960
Shing Mun Tunnel	Hong Kong, China	2004	65	50% gasoline	0.131 ± 0.037	1.845 ± 0.434	0.878 ± 0.308	0.115 ± 0.030	0.115	[31, 40]
Taipei Tunnel	Taipei, Taiwan	2002		Total fleet		3.640 ± 0.260	0.900 ± 0.180	0.440 ± 0.060	0.240	[36]
Zhujiang Tunnel	Guangzhou, China	1999	49	Total fleet		15.400 ± 6.630	1.380 ± 0.480	1.860 ± 1.760	0.520 ± 0.070	[34, 38]
				Car		12.510	0.420	4.700
				Taxi		16.640	2.000	0.540
North Ring Road Tunnel	Xi’an, China	1996	42.2	66.7% gasoline		33.279 ± 12.158	4.061 ± 1.981	3.577 ± 1.820		[27]
Caldecott Tunnel	San Francisco, USA	1997		Light-duty	0.006					[41]
				Heavy-duty	0.430 ± 0.079
Wenchang Gate-Peace Gate Tunnel (this study)	Xi’an, China	2015	33.18	Total fleet	0.006 ± 0.005	1.097 ± 0.398	0.159 ± 0.092	0.179 ± 0.089	0.317 ± 0.172
				Car	0.004	1.085	0.078	0.123	0.060
				Taxi	0.038	1.167	0.582	0.442	1.650