Daily Variation in Chemical Characteristics of Urban Ultrafine Aerosols and Inference of Their Sources

Ning, Zhi; Geller, Michael D.; Moore, Katharine F.; Sheesley, Rebecca J.; Schauer, James J.; Sioutas, Constantinos

doi:10.1021/es070653g

Cited by 109 publications

(92 citation statements)

References 45 publications

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“…This site is regarded as a typical urban background site in Los Angeles. In the cooler months of late spring and late fall, a characteristic early morning peak, associated with mostly light-duty gasoline vehicle morning commute, is observed from 05:00-10:00 h. Advancing into summer months, this peak is not as robust and eventually flattens, as higher temperatures during the early mornings increase mixing heights, thus enhancing dispersion, and also lead to possible volatilization of semivolatile organics bound to PM from traffic emissions (Biswas et al, 2007;Ning et al, 2007). However, another peak emerges, which has its crest in early afternoon, and in summer months is associated with the highest diurnal values for PNC.…”

Section: Diurnal and Seasonal Variationsmentioning

confidence: 99%

“…Once formed, particles are transformed in the atmosphere, by coagulation and condensation of semivolatile vapors on their surface as they are advected downwind. This long-range transport as well as photochemical particle formation in the atmosphere can lead to increased particle number observations downwind of urban areas (Kim et al, 2002;Fine et al, 2004b;Verma et al, 2009;Ning et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

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Inter-community variability in total particle number concentrations in the eastern Los Angeles air basin

et al. 2010

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Abstract. Ultrafine Particles (UFP) can display sharp gradients in their number concentrations in urban environment due to their transient nature and rapid atmospheric processing. The ability of using air pollution data generated at a central monitoring station to assess exposure relies on our understanding of the spatial variability of a specific pollutant associated with a region. High spatial variation in the concentrations of air pollutants has been reported at scales of 10s of km for areas affected by primary emissions. Spatial variability in particle number concentrations (PNC) and size distributions needs to be investigated, as the representativeness of a monitoring station in a region is premised on the assumption of homogeneity in both of these metrics. This study was conducted at six sites, one in downtown Los Angeles and five located about 40-115 km downwind in the receptor areas of Los Angeles air basin. PNC and size distribution were measured using Condensation Particle Counters (CPC) and Scanning Mobility Particle Sizer (SMPS). The seasonal and diurnal variations of PNC implied that PNC might vary significantly with meteorological conditions, even though the general patterns at the sites may remain generally similar across the year due to consistency of sources around them. Regionally transported particulate matter (PM) from upwind urban areas of Los Angeles lowered spatial variation by acting as a "homogenizing" factor during favorable meteorological conditions. Spatial variability also increased during hours of the day during which the effects of local sources predominate. The spatial variability associated with PNC (quantified using Coefficients of Divergence, CODs), averaged about 0.3, which was generally lower than that based on specific size ranges. Results showed an inverse relationship of COD with particles size, with fairly uniform values in the particle rangeCorrespondence to: C. Sioutas (sioutas@usc.edu) which is associated with regional transport. Our results suggest that spatial variability, even in the receptor regions of Los Angeles Basin, should be assessed for both PNC and size distributions, and should be interpreted in context of seasonal and diurnal influences, and suitably factored if values for exposure are ascertained using a central monitoring station.

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Section: Diurnal and Seasonal Variationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Inter-community variability in total particle number concentrations in the eastern Los Angeles air basin

et al. 2010

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“…Ning et al 78 studied the diurnal variations of UFPM concentrations and chemical composition at an urban site (downtown Los Angeles, CA) using a MOUDI to collect two 3-hr samples daily (6:00 to 9:00 a.m. and 1:00 to 4:00 p.m.). The UFPM mass concentrations ranged from approximately 3 to 7 g/m…”

Section: ϫ3mentioning

confidence: 99%

Current Understanding of Ultrafine Particulate Matter Emitted from Mobile Sources

Seigneur

2009

Journal of the Air & Waste Management Association

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The physics and chemistry of ultrafine particulate matter (UFPM) associated with mobile source emissions is reviewed. UFPM includes those particles that are less than 0.1 m in diameter. Measurements of UFPM emitted from mobile sources have been conducted in the laboratory, on roadways, and downwind of roadways. In addition, UFPM formation and evolution have been modeled and the modeling results have been compared with available measurements. The results of those measurement programs and modeling studies are synthesized into a coherent description of the formation of UFPM in mobile source emissions and its subsequent evolution in the ambient atmosphere. Recommendations are provided to address the gaps in our current understanding of the processes leading to the formation of UFPM, its chemical composition, and its evolution in the atmosphere.

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“…The PENS-PM 0.1 of 18.1 μg/m 3 was highest during welding, followed by that of 15.3 μg/m 3 during milling and lowest of 10.5 μg/m 3 during polishing. These PM 0.1 levels are considered quite high, given the very small sizes and hence mass of nanoparticles and in comparison to PM 0.1 levels of less than 5 μg/m 3 measured in urban and roadside air (e.g., Geller et al, 2002;Ning et al, 2007).…”

Section: Personal Exposure Levels Of Pm 4 and Pm 01mentioning

confidence: 89%

Field Application of a Newly Developed Personal Nanoparticle Sampler to Selected Metalworking Operations

Young

Lin

et al. 2013

Aerosol Air Qual. Res.

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A personal nanoparticle sampler (PENS) that simultaneously collects respirable particles (< 4 μm) and nanoparticles (< 0.1 μm) has recently been developed and calibrated in the laboratory. This study aims to evaluate the performance of the PENS in the workplace, and to determine the exposure characteristics during selected metalworking operations. Metal polishing/buffing, spot welding, and milling operations were selected to represent sources of solid metal particles, fume aggregates and metalworking fluid mists, respectively. In each operation, personal samples of a side-by-side PENS and SKC respirable dust aluminum cyclone were taken concurrently with ambient particle number size distribution measurements. The PENS-measured respirable particle mass concentrations (PM 4 ) showed remarkable accuracy with respect to the reference SKC cyclone, regardless of particle type. The PENS-derived nanoparticle effective densities agreed reasonably well with the bulk densities expected for the substrate and materials in use. During the metalworking operations, the nanoparticle mass concentrations (PM 0.1 ) were poorly associated with the PM 4 but strongly correlated with the ambient nanoparticle number concentrations (PN 0.1 ), due to the persistent, elevated levels of nanoparticles formed during the operations. Overall, these results suggest that the PENS is applicable for use in the workplace to assess respirable and nanoparticle personal exposure, and that metal polishing/buffing, welding and milling generate a considerable amount of nanoparticles.

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Daily Variation in Chemical Characteristics of Urban Ultrafine Aerosols and Inference of Their Sources

Cited by 109 publications

References 45 publications

Inter-community variability in total particle number concentrations in the eastern Los Angeles air basin

Inter-community variability in total particle number concentrations in the eastern Los Angeles air basin

Current Understanding of Ultrafine Particulate Matter Emitted from Mobile Sources

Field Application of a Newly Developed Personal Nanoparticle Sampler to Selected Metalworking Operations

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