Evolution of particle number distribution near roadways. Part II: the ‘Road-to-Ambient’ process

Zhang, K.Max; Wexler, Anthony S.; Zhu, Yi; Hinds, William C.; Sioutas, Constantinos

doi:10.1016/j.atmosenv.2004.06.044

Cited by 247 publications

(181 citation statements)

References 11 publications

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“…At 60 and 90 m distance from I-405, Zhu et al (2002b) found a dominant mode at about 40 nm. This, as well as the 50 nm mode in this study might be explained by condensational growth (Zhang et al 2004a). With the wind direction predominantly parallel to the freeway, such growth could occur while the aging particles remain close to the freeway.…”

Section: Size Distribution Of Ambient Aerosolmentioning

confidence: 91%

Physical and Chemical Characteristics and Volatility of PM in the Proximity of a Light-Duty Vehicle Freeway

Kühn¹,

Biswas

Fine

et al. 2005

Aerosol Science and Technology

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Section: Size Distribution Of Ambient Aerosolmentioning

confidence: 91%

Physical and Chemical Characteristics and Volatility of PM in the Proximity of a Light-Duty Vehicle Freeway

Kühn¹,

Biswas

Fine

et al. 2005

Aerosol Science and Technology

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“…We show here that traffic-emitted NCA increases the aerosol particle number concentrations in environments near traffic. Previous research has shown that particle concentrations decrease when moving away from the roadway; this effect is generally attributed to coagulation and dilution (2,26,34), although evaporation has been suggested as well (35). The scavenging time scale of diluted NCA is of the order of 20 min to reach the levels observed for urban background aerosol; thus, NCA can be transported for several kilometers before removal by loss processes, meaning that in urban areas, the traffic-originated NCA is likely ubiquitous and contributes significantly to the background levels.…”

Section: Tunnel Motorwaymentioning

confidence: 99%

Traffic is a major source of atmospheric nanocluster aerosol

Rönkkö

Kuuluvainen

Karjalainen

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

203

132

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In densely populated areas, traffic is a significant source of atmospheric aerosol particles. Owing to their small size and complicated chemical and physical characteristics, atmospheric particles resulting from traffic emissions pose a significant risk to human health and also contribute to anthropogenic forcing of climate. Previous research has established that vehicles directly emit primary aerosol particles and also contribute to secondary aerosol particle formation by emitting aerosol precursors. Here, we extend the urban atmospheric aerosol characterization to cover nanocluster aerosol (NCA) particles and show that a major fraction of particles emitted by road transportation are in a previously unmeasured size range of 1.3-3.0 nm. For instance, in a semiurban roadside environment, the NCA represented 20-54% of the total particle concentration in ambient air. The observed NCA concentrations varied significantly depending on the traffic rate and wind direction. The emission factors of NCA for traffic were 2.4·10 15 (kg fuel ) −1 in a roadside environment, 2.6·10 15 (kg fuel ) −1 in a street canyon, and 2.9·10 15 (kg fuel ) −1 in an on-road study throughout Europe. Interestingly, these emissions were not associated with all vehicles. In engine laboratory experiments, the emission factor of exhaust NCA varied from a relatively low value of 1.6·10 12 (kg fuel ) −1 to a high value of 4.3·10 15 (kg fuel ) −1 . These NCA emissions directly affect particle concentrations and human exposure to nanosized aerosol in urban areas, and potentially may act as nanosized condensation nuclei for the condensation of atmospheric low-volatile organic compounds.nanocluster aerosol | atmospheric aerosol | combustion-derived nanoparticles | air pollution | traffic emission D etailed characterization of aerosol sources is required to understand climate impacts and health effects of atmospheric aerosols, as well as to develop technologies and policies capable of mitigating air pollution in urbanized areas. In densely populated areas, one of the most significant source of particles is traffic (1, 2). Owing to their small size and complicated chemical and physical characteristics (3-6), atmospheric particles resulting from traffic emissions pose a significant risk to human health (7-12), and also contribute to anthropogenic forcing of climate (13,14). Previous research on vehicular emissions has demonstrated the presence of soot and ash (3, 15) and solid sub-10-nm core particles (4-6) in primary emissions from vehicles and engines and their variation, depending on vehicle technologies (4, 6), the properties of fuels and lubricant oils (15, 16), and driving conditions (15-17). In addition to particles, exhaust typically contains species that reside in the gaseous phase in the undiluted high-temperature exhaust (5, 18, 19) but condense or even nucleate to the particle phase immediately after the exhaust is released to the atmosphere. Here, we term such aerosols delayed primary aerosols, because particle precursors exist already in the u...

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“…Concentrations of primary pollutants (e.g., particulate matter (PM), nitrogen oxides (NO x ), carbon monoxide (CO), mobile source air toxics (MSATs)) in vehicle tailpipes, just before they are emitted into the atmosphere, are often two to four orders of magnitude higher than concentrations measured in ambient air (Zhang et al, 2004). Motor vehicles also emit and re-suspend PM constituents from brake, tire, and pavement wear during operation on the road.…”

Section: Introductionmentioning

confidence: 99%

Influence of solid noise barriers on near-road and on-road air quality

Baldauf

Isakov

Deshmukh

et al. 2016

Atmospheric Environment

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h i g h l i g h t sMobile monitoring measured near-road air quality impacts of a solid, noise barrier. Downwind concentration reductions of up to 50% occurred behind the barrier. Downwind reductions were highest within the first 50 m from the road. Reductions extended as far as 300 m from the road. On-road levels did not increase in front of barrier, contrary to model predictions. a r t i c l e i n f o Public health concerns regarding adverse health effects for populations spending significant amounts of time near high traffic roadways has increased substantially in recent years. Roadside features, including solid noise barriers, have been investigated as potential methods that can be implemented in a relatively short time period to reduce air pollution exposures from nearby traffic. A field study was conducted to determine the influence of noise barriers on both on-road and downwind pollutant concentrations near a large highway in Phoenix, Arizona, USA. Concentrations of nitrogen dioxide, carbon monoxide, ultrafine particles, and black carbon were measured using a mobile platform and fixed sites along two limitedaccess stretches of highway that contained a section of noise barrier and a section with no noise barrier at-grade with the surrounding terrain. Results of the study showed that pollutant concentrations behind the roadside barriers were significantly lower relative to those measured in the absence of barriers. The reductions ranged from 50% within 50 m from the barrier to about 30% as far as 300 m from the barrier. Reductions in pollutant concentrations generally began within the first 50 m of the barrier edge; however, concentrations were highly variable due to vehicle activity behind the barrier and along nearby urban arterial roadways. The concentrations on the highway, upwind of the barrier, varied depending on wind direction. Overall, the on-road concentrations in front of the noise barrier were similar to those measured in the absence of the barrier, contradicting previous modeling results that suggested roadside barriers increase pollutant levels on the road. Thus, this study suggests that noise barriers do reduce potential pollutant exposures for populations downwind of the road, and do not likely increase exposures to traffic-related pollutants for vehicle passengers on the highway.Published by Elsevier Ltd.

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Evolution of particle number distribution near roadways. Part II: the ‘Road-to-Ambient’ process

Cited by 247 publications

References 11 publications

Physical and Chemical Characteristics and Volatility of PM in the Proximity of a Light-Duty Vehicle Freeway

Physical and Chemical Characteristics and Volatility of PM in the Proximity of a Light-Duty Vehicle Freeway

Traffic is a major source of atmospheric nanocluster aerosol

Influence of solid noise barriers on near-road and on-road air quality

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