Real-World Emission Factors of Fine and Ultrafine Aerosol Particles for Different Traffic Situations in Switzerland

Abstract

Extended field measurements of particle number (size distribution of particle diameters, D, in the range between 18 nm and 10 microm), surface area concentrations, and PM1 and PM10 mass concentrations were performed in Switzerland to determine traffic emissions using a comprehensive set of instruments. Measurements took place at roads with representative traffic regimes: at the kerbside of a motorway (120 km h(-1)), a highway (80-100 km h(-1)), and in an urban area with stop-and-go traffic (0-50 km h(-1)) regulated by light signals. Mean diurnal variations showed that the highest pollutant concentrations were during the morning rush hours, especially of the number density in the nanoparticle size range (D <50 nm). From the differences between up- and downwind concentrations (or differences between kerbside and background concentrations for the urban site), "real-life" emission factors were derived using NOx concentrations to calculate dilution factors. Particle number and volume emission factors of different size ranges (18-50 nm, 18-100 nm, and 18-300 nm) were derived for the total vehicle fleet and separated into a light-duty (LDV) and a heavy-duty vehicle (HDV) contribution. The total particle number emissions per vehicle were found to be about 11.7-13.5 x 10(14) particles km(-1) for constant speed (80-120 km h(-1) and 3.9 x 10(14) particles km(-1) for urban driving conditions. LDVs showed higher emission factors at constant high speed than under urban disturbed traffic flow. In contrast, HDVs emitted more air pollutants during deceleration and acceleration processes in stop-and-go traffic than with constant speed of about 80 km h(-1). On average, one HDV emits a 10-30 times higher amount of particulate air pollutants (in terms of both number and volume) than one LDV.

Size Resolved Particle Number Emission Factors of Motorway Traffic Differentiated between Heavy and Light Duty Vehicles

“…Using particle size classes from 30-10,000 nm and 3-3000 nm Corsmeier et al (2005) and Ban-Weiss et al (2010) found comparable results with around 85% and 88% lower EF for LDV compared to the HDV. In other studies much higher differences between LDV and HDV emission factors were detected, ranging from a factor 10 by Imhof et al (2005) up to a factor 149 by Birmili et al (2009).…”

“…If the emission factor for a similar size range as in this study is calculated, based on e.g., data provided by Imhof et al (2005) for the size range 18-300 nm, their emission factor was only a factor two higher. In contrast, Corsmeier et al (2005) detected lower emission factor for both HDV and LDV by using instruments which started at particle sizes > 30 nm.…”

“…Most studies which calculated number emission factors were conducted in tunnel systems and the tunnel ventilation was used to calculate dilution conditions (Kirchstetter et al, 1999;Gidhagen et al, 2003;Kristensson et al, 2004;Geller et al, 2005;Ban-Weiss et al, 2010). Furthermore, different model systems were applied for the calculation of the dilution of the exhaust emissions (Jamriska and Morawska 2001;Corsmeier et al, 2005;Birmili et al, 2009;Wehner et al, 2009) or the NO x tracer method was used for the calculation of the dilution, like by Imhof et al (2005) and Wang et al (2010).…”

Winter and summer time size distributions and densities of traffic-related aerosol particles at a busy highway in Helsinki

“…According to Imhof et al (2005a); Janhäll et al (2004); Ketzel et al (2004) and Wåhlin et al (2001) the size distributions measured at the roadside were dominated by nucleation mode particles with a relatively constant peak size of 20 nm. In laboratory and chase measurements the nucleation mode existence and peak diameter show great variation (Kittelson et al, 2004;Vaaraslahti et al, 2004;Rönkkö et al, 2006).…”

Zone of influence for particle number concentrations at signalised traffic intersections

“…This can be explained by ~40% higher driving speed at T4w-nb than those at TI4w-wb while average driving speed at both three-way TIs was almost equal (Table 7). Particle number emission increases with the increase in driving speed due to higher engine load (Imhof et al, 2005;Kumar et al, 2011;Wang et al, 2010 of ZoI depends predominantly on idling time while average PNCs depends on driving speed of the road vehicles. Table 6.…”