Size resolved traffic emission factors of submicrometer particles

Janhäll, Sara; Jönsson, Anders; Molnár, Péter; Svensson, Erik; Hallquist, Mattias

doi:10.1016/j.atmosenv.2004.04.018

Cited by 72 publications

(53 citation statements)

References 22 publications

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“…In the winter time the concentration peaking was a bit stronger during the morning rush hours than during evening rush hours. Williams et al (2000), Molnár et al (2002), Wehner et al (2002), Charron and Harrison (2003), and Janhäll et al (2004) observed stronger concentration peaks during the morning rush hour. Wehner et al associated the higher morning concentrations with the higher truck traffic rate.…”

Section: Correlation Of Particle Emissions and Traffic Ratementioning

confidence: 99%

“…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).…”

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confidence: 99%

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

et al. 2006

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Abstract. Number concentrations and size distributions of traffic related aerosol particles were measured at a roadside in Helsinki during two winter campaigns (10-26 February 2003, 28 January-12 February 2004 and two summer campaigns (12-27 August 2003, 6-20 August 2004. The measurements were performed simultaneously at distances of 9 m and 65 m from the highway. Total number concentrations were measured by a condensation particle counter (CPC) and particle size distributions by a scanning mobility particle sizer (SMPS) and an electrical low pressure impactor (ELPI). This study concentrates on data that were measured when the wind direction was from the road to the measurement site. The total concentrations in the wintertime were 2-3 times higher than in the summertime and the concentrations were dominated by nucleation mode particles. The particles smaller than 63 nm (aerodynamic diameter) constituted ∼90% of all particles in the wintertime and ∼80% of particles in the summer time. The particle total concentration increased with increasing traffic rate. The effect of traffic rate on particles smaller than 63 nm was stronger than on the larger particles. The particle distributions at the roadside consisted of two distinguishable modes. The geometric mean diameter (GMD) of nucleation mode (Mode 1) was 20.3 nm in summer and 18.9 nm in winter. The GMD of the larger mode consisting mostly of traffic related soot particles (Mode 2) was 72.0 nm in summer and 75.1 nm in winter. The GMD values of the modes did not depend on the traffic rate. The average particle density for each mode was determined by a parallel density fitting method based on the size distribution measurement made by ELPI and SMPS. The average density value for Mode 1 particles Correspondence to: A. Virtanen (annele.virtanen@tut.fi) was 1.0±0.13 g/cm 3 and 1.0±0.07 g/cm 3 both in summer and winter respectively, while the average density value for Mode 2 was 1.5±0.1 g/cm 3 and 1.8±0.3 g/cm 3 for summer and winter, respectively.

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Section: Correlation Of Particle Emissions and Traffic Ratementioning

confidence: 99%

mentioning

confidence: 99%

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

et al. 2006

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“…Vogt et al, 2003;Zhang et al, 2004;Ntziachristos et al, 2007;Vu et al, 2015b) and the growth of nucleation particles from diesel vehicles (Mayer and Ristovski, 2007;Wehner et al, 2009). For example, Charron and Harrison (2003) reported that particles in the range of 30-60 nm show a stronger association with light-duty traf- fic at a traffic hotspot in central London (Marylebone Rd); Janhäll et al (2004) reported an average particle size distribution peaking at 15-30 nm during morning peak high traffic intensity in the city of Göteborg (Sweden), which has a car fleet comparable to the UK; Ntziachristos et al (2007) found a sharp mode at 20-30 nm in sampling from engine exhausts. In addition, PMF factors with similar modal structures were found in other studies and were attributed to road traffic emissions: among others, Harrison et al (2011) linked a factor peaking at 20 nm to primary road traffic emissions near a major UK highway; Masiol et al (2016) measured PNSD in an international airport in northern Italy during summer and interpreted a factor with a clear mode at 35-40 nm as road traffic from the nearby city; Beddows et al (2015) and Vu et al (2016) found traffic factors with modal diameter at around 30 nm in an urban background site in London (North Kensington); Sowlat et al (2016) reported a factor peaking at 20-40 nm in number concentration and at around 30-40 nm in volume concentration in Los Angeles (US) and interpreted it as traffic tailpipe emissions.…”

Section: Warm Seasonmentioning

confidence: 99%

Sources of sub-micrometre particles near a major international airport

Masiol

Harrison

et al. 2017

Atmos. Chem. Phys.

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Abstract. The international airport of Heathrow is a major source of nitrogen oxides, but its contribution to the levels of sub-micrometre particles is unknown and is the objective of this study. Two sampling campaigns were carried out during warm and cold seasons at a site close to the airfield (1.2 km). Size spectra were largely dominated by ultrafine particles: nucleation particles (< 30 nm) were found to be ∼ 10 times higher than those commonly measured in urban background environments of London. Five clusters and six factors were identified by applying k means cluster analysis and positive matrix factorisation (PMF), respectively, to particle number size distributions; their interpretation was based on their modal structures, wind directionality, diurnal patterns, road and airport traffic volumes, and on the relationship with weather and other air pollutants. Airport emissions, fresh and aged road traffic, urban accumulation mode, and two secondary sources were then identified and apportioned. The fingerprint of Heathrow has a characteristic modal structure peaking at < 20 nm and accounts for 30-35 % of total particles in both the seasons. Other main contributors are fresh (24-36 %) and aged (16-21 %) road traffic emissions and urban accumulation from London (around 10 %). Secondary sources accounted for less than 6 % in number concentrations but for more than 50 % in volume concentration. The analysis of a strong regional nucleation event showed that both the cluster categorisation and PMF contributions were affected during the first 6 h of the event. In 2016, the UK government provisionally approved the construction of a third runway; therefore the direct and indirect impact of Heathrow on local air quality is expected to increase unless mitigation strategies are applied successfully.

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“…NOx and CO (e.g., Janhäll et al, 2004;Sardar et al, 2005;Westerdahl et al, 2005;Hagler et al, 2010), although in varying degrees depending on lower UFP cut-off diameter, distance to traffic, traffic composition and season. Morawska et al (2008) conclude that while in general there is a reasonably good correlation between UFP and traffic emitted gaseous pollutants, the existence and the degree of correlation varies.…”

Section: Log-linear Regression Analysismentioning

confidence: 99%