Transformation of size distributions of emitted particles in streets

Vignati, E.; Berkowicz, Ruwim; Palmgren, Finn; Lyck, E.; Hummelshøj, P.

doi:10.1016/s0048-9697(99)00188-6

Cited by 50 publications

(31 citation statements)

References 8 publications

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“…Researchers who have conducted experimental and theoretical studies on the transportation and transformation of vehicle particle emissions in the atmosphere often have concluded that the rapid dilution of the exhaust plume made coagulation insignificant. 20,42 However, in this study, the observed size distribution changes indicate that coagulation is not negligible.…”

Section: Traffic Effectscontrasting

confidence: 62%

Concentration and Size Distribution of Ultrafine Particles Near a Major Highway

Zhu

Hinds

Kim

et al. 2002

Journal of the Air & Waste Management Association

898

656

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Motor vehicle emissions usually constitute the most significant source of ultrafine particles (diameter <0.1 µm) in an urban environment, yet little is known about the concentration and size distribution of ultrafine particles in the vicinity of major highways. In the present study, particle number concentration and size distribution in the size range from 6 to 220 nm were measured by a condensation particle counter (CPC) and a scanning mobility particle sizer (SMPS), respectively. Measurements were taken 30, 60, 90, 150, and 300 m downwind, and 300 m upwind, from Interstate 405 at the Los Angeles National Cemetery. At each sampling location, concentrations of CO, black carbon (BC), and particle mass were also measured by a Dasibi CO monitor, an aethalometer, and a DataRam, respectively. The range of average concentration of CO, BC, total particle number, and mass concentration at 30 m was 1.7-2.2 ppm, 3.4-10.0 µg/m 3 , 1.3-2.0 × 10 5 /cm 3 , and 30.2-64.6 µg/m 3 , respectively. For the conditions of these measurements, relative concentrations of CO, BC, and particle number tracked each other well as distance from the freeway increased.Particle number concentration (6-220 nm) decreased exponentially with downwind distance from the freeway. Data showed that both atmospheric dispersion and coagulation contributed to the rapid decrease in particle number concentration and change in particle size distribution with increasing distance from the freeway. Average traffic flow during the sampling periods was 13,900 vehicles/hr. Ninetythree percent of vehicles were gasoline-powered cars or light trucks. The measured number concentration tracked traffic flow well. Thirty meters downwind from the freeway, three distinct ultrafine modes were observed with geometric mean diameters of 13, 27, and 65 nm. The smallest mode, with a peak concentration of 1.6 × 10 5 /cm 3

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Section: Traffic Effectscontrasting

confidence: 62%

Concentration and Size Distribution of Ultrafine Particles Near a Major Highway

Zhu

Hinds

Kim

et al. 2002

Journal of the Air & Waste Management Association

898

656

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“…BS is believed to be a measurement of particles in the submicrometre range (Horvath, 1995), which to some extent will be directly emitted ultrafine particles from diesel vehicles. The spatial variation found for BS is probably due to a rapid dilution of the BS sources, such as diesel exhaust, rather than condensation to larger particles (Vignati et al, 1999).…”

Section: Discussionmentioning

confidence: 92%

Personal exposure to PM2.5, black smoke and NO2 in Copenhagen: relationship to bedroom and outdoor concentrations covering seasonal variation

Sørensen

Loft

Andersen³

et al. 2005

J Expo Sci Environ Epidemiol

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Epidemiological studies have found negative associations between human health and particulate matter in urban air. In most studies outdoor monitoring of urban background has been used to assess exposure. In a field study, personal exposure as well as bedroom, front door and background concentrations of PM 2.5 , black smoke (BS), and nitrogen dioxide (NO 2 ) were measured during 2-day periods in 30 subjects (20-33 years old) living and studying in central parts of Copenhagen. The measurements were repeated in the four seasons. Information on indoor exposure sources such as environmental tobacco smoke (ETS) and burning of candles was collected by questionnaires. The personal exposure, the bedroom concentration and the front door concentration was set as outcome variable in separate models and analysed by mixed effect model regression methodology, regarding subject levels as a random factor. Seasons were defined as a dichotomised grouping of outdoor temperature (above and below 81C). For NO 2 there was a significant association between personal exposure and both the bedroom, the front door and the background concentrations, whereas for PM 2.5 and BS only the bedroom and the front door concentrations, and not the background concentration, were significantly associated to the personal exposure. The bedroom concentration was the strongest predictor of all three pollution measurements. The association between the bedroom and front door concentrations was significant for all three measurements, and the association between the front door and the background concentrations was significant for PM 2.5 and NO 2 , but not for BS, indicating greater spatial variation for BS than for PM 2.5 and NO 2 . For NO 2 , the relationship between the personal exposure and the front door concentration was dependent upon the ''season'', with a stronger association in the warm season compared with the cold season, and for PM 2.5 and BS the same tendency was seen. Time exposed to burning of candles was a significant predictor of personal PM 2.5 , BS and NO 2 exposure, and time exposed to ETS only associated with personal PM 2.5 exposure. These findings imply that the personal exposure to PM 2.5 , BS and NO 2 depends on many factors besides the outdoor levels, and that information on, for example, time of season or outdoor temperature and residence exposure, could improve the accuracy of the personal exposure estimation. Keywords: urban air, particulate matter, PM 2.5 , black smoke, nitrogen dioxide, personal exposure, seasonal variation. Journal of Exposure Analysis and Environmental Epidemiology IntroductionNumerous studies have shown that exposure to high outdoor particle levels causes increased morbidity and mortality of respiratory diseases and cardiovascular diseases (Brunekreef and Holgate, 2002;Pope et al., 2002). Exposure to particles has been assessed by outdoor monitoring of urban background levels in most of these studies. It has been shown that people spend most of their time indoor and that indoors sources to air pollutants are n...

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“…Moreover, the total net effect on the particle number concentration may not be affected notably (Kumar et al, 2008b(Kumar et al, , 2009a due to the competition between the removal processes. Vignati et al (1999) found that due to rapid dilution only very small particles (2 nm) have a coagulation time scale which is comparable with typical residence times of pollutants in a street. Zhu et al (2002) reported that atmospheric dilution and coagulation near a highway played important roles in the rapid decrease of particles number concentrations and transformation of the size distribution.…”

Section: Importance Of Deposition and Coagulationmentioning

confidence: 83%

Modelling the Mixing of Size Resolved Traffic Induced and Background Ultrafine Particles from an Urban Street Canyon to Adjacent Backyards

Nikolova

Janssen

Vos

et al. 2014

Aerosol Air Qual. Res.

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By means of numerical simulations the aims of this study are as follows: (1) to investigate the dispersion and mixing of ultrafine particles (UFP) with pre-existing size resolved UFP in a street canyon and its vicinity with the ENVI-met 3D microscale model; (2) to show the effects of boundary conditions, like wind direction and traffic emissions, on the UFP concentration in the near vicinity; and (3) to evaluate the importance of deposition and coagulation at the street scale. The decrease in UFP concentration in nucleation mode particles (diameter < 30 nm) and Aitken mode particles (diameter between 30-100 nm) downwind of the street canyon is caused by the large differences in the size distributions of the emissions and the background. Based on the wind direction and traffic emissions, the UFP concentration over the rooftop increases by 23% for the South-West wind up to 165% for the Northern wind. The background distribution for the South-West wind direction remains mono-modal, with a peak in the Aitken mode as a result of the relatively low contribution of advected particles from the street canyon. For the Northern wind the background size distribution transforms to a bi-modal distribution, with peaks in the nucleation and the Aitken modes as a result of the high UFP concentration advected from the boulevard. The overall effect of deposition and coagulation on the UFP is negligible for the cases considered in this study. Overall, deposition is more efficient and faster than coagulation in removing particles, and especially those in the nucleation mode.

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Transformation of size distributions of emitted particles in streets

Cited by 50 publications

References 8 publications

Concentration and Size Distribution of Ultrafine Particles Near a Major Highway

Concentration and Size Distribution of Ultrafine Particles Near a Major Highway

Personal exposure to PM2.5, black smoke and NO2 in Copenhagen: relationship to bedroom and outdoor concentrations covering seasonal variation

Modelling the Mixing of Size Resolved Traffic Induced and Background Ultrafine Particles from an Urban Street Canyon to Adjacent Backyards

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