Black carbon, particle number concentration and nitrogen oxide emission factors of random in-use vehicles measured with the on-road chasing method

Abstract

Abstract. The chasing method was used in an on-road measurement campaign, and emission factors (EF) of black carbon (BC), particle number (PN) and nitrogen oxides (NOx) were determined for 139 individual vehicles of different types encountered on the roads. The aggregated results provide EFs for BC, NOx and PN for three vehicle categories: goods vehicles, gasoline and diesel passenger cars. This is the first on-road measurement study where BC EFs of numerous individual diesel cars were determined in real-world driving conditions. We found good agreement between EFs of goods vehicles determined in this campaign and the results of previous studies that used either chasing or remote-sensing measurement techniques. The composition of the sampled car fleet determined from the national vehicle registry information is reflective of Eurostat statistical data on the Slovenian and European vehicle fleet. The median BC EF of diesel and gasoline cars that were in use for less than 5 years decreased by 60 and 47 % from those in use for 5–10 years, respectively; the median NOx and PN EFs of goods vehicles that were in use for less than 5 years decreased from those in use for 5–10 years by 52 and 67 %, respectively. Surprisingly, we found an increase of BC EFs in the newer goods vehicle fleet compared to the 5–10-year old one. The influence of engine maximum power of the measured EFs showed an increase in NOx EF from least to more powerful vehicles with diesel engines. Finally, a disproportionate contribution of high emitters to the total emissions of the measured fleet was found; the top 25 % of emitting diesel cars contributed 63, 47 and 61 % of BC, NOx and PN emissions respectively. With the combination of relatively simple on-road measurements and sophisticated post processing, individual vehicle EF can be determined and useful information about the fleet emissions can be obtained by exactly representing vehicles which contribute disproportionally to vehicle fleet emissions; and monitor how the numerous emission reduction approaches are reflected in on-road driving conditions.

Chemical and physical characterization of traffic particles in four different highway environments in the Helsinki metropolitan area

“…For the CO 2 production rate, we adopted a value provided by the VTT Technical Research Centre of Finland, CMF CO 2 / CMF fuel = 3141 g (kg fuel) −1 , the same as used by Yli-Tuomi et al (2004). Similar values were reported in other papers like Ježek et al (2015). In order to characterize the fleet more representatively, 2 min averages were used in the emission factor calculations.…”

“…Furthermore, the authors report that for the diesel passenger cars the relative amount of NO 2 increased as the NO 2 / NO x ratio was 10-15 % for Euro III and older type vehicles whereas it was 25-30 % for Euro IV-V type vehicles. Ježek et al (2015) observed reductions in the EF NO x for passenger cars and diesel heavy goods vehicles but no reduction for diesel passenger cars compared to those ten or more years old.…”

Technical note: Use of an atmospheric simulation chamber to investigate the effect of different engine conditions on unregulated VOC-IVOC diesel exhaust emissions

“…Gentner et al, 2013;Liu et al, 2015;Ježek et al, 2015;Zavala et al, 2006;Jiang et al, 2005;Kristensson et al, 2004;Fraser et al, 1998;Miguel et al, 1998;Staehelin et al, 1998). These measurements provide a compositional overview of the exhaust emissions from the on-road vehicular fleet, consisting of a vast range of vehicle types (e.g.…”

Russia's black carbon emissions: focus on diesel sources

“…In Beijing, Wang et al (2011) found that approximately 5 % of the trucks are responsible for 50 % of the BC emissions. In Slovenia, a study of 139 individual vehicles of different types showed that 25 % of the highest-emitting diesel vehicles produce 63 % of the BC emissions (Ježek et al, 2015). Preble et al (2015) found that 20 % of trucks emit 80 % of the BC emissions from the Port of Oakland truck fleet (Preble et al, 2015).…”

“…Using fuel-based emission factors from the EEA emission guidebook and NIIAT emission factors, BC emissions from on-road transport were estimated to be about 20.0 Gg (Evans et al, 2015). Similarly, Kholod and Evans (2016) use the Global Change Assessment Model (GCAM) to build a forecast for BC emissions from on-road transport in Russia. Total BC emissions from on-road transport were estimated to be about 20.0 Gg in 2015.…”