Effects of the COVID-19 pandemic on public bus occupancy and real-world tailpipe emissions of gaseous pollutants per passenger kilometer traveled

Table 1 Test vehicle characteristics and the sample size

Parameters	Bus	Car
Make	King Long	Toyota
Model year	2013	2008
Engine displacement volume (cm³)	6692	1497
Tailpipe emission control	DPF ^a, SCR ^b	TWC ^c
Emission certification	Phase-5 ^d	Phase-4 ^e
Accumulated mileage (km)	750,550	228,200
Fuel	Diesel	Gasoline
Number of on-road emission tests	4	4
Total distance driven for on-road emission tests (km)	92.3	91.5
Number of valid data points ^f	25,320	15,835

^a Diesel particulate filter
^b Selective catalytic reduction
^c Three-way catalytic converter
^d Implemented in 2012 in Taiwan, the emission limits are 1.5, 0.46, 2.0, and 0.02 g kWh^− 1 for CO, THC, NO_x, and PM, respectively
^e Implemented in 2008 in Taiwan, the emission limits are 2.11, 0.045, and 0.07 g km^− 1 for CO, THC, and NO_x, respectively
^f The data recording frequency of the components of the onboard emission measurement system was 1 Hz

ISSN: 2468-2039