On-line measurement of size distribution and effective density of submicron aerosol particles

Ristimäki, Jyrki; Virtanen, Annele; Marjamäki, Marko; Rostedt, Antti; Keskinen, Jorma

doi:10.1016/s0021-8502(02)00106-4

Cited by 104 publications

(90 citation statements)

References 26 publications

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“…Particle density was estimated using the parallel measurement method described by Ristimäki et al (2002) and Virtanen et al (2004a). The method is based on simultaneous ("parallel") distribution measurement with ELPI and SMPS and further on the relationship between particle aerodynamic size, mobility size and effective density.…”

Section: Methods For Estimating Particle Densitymentioning

confidence: 99%

“…To limit the degrees of freedom in the density search procedure, a constant density is assumed within each mode. The main difference to the single mode case (Ristimäki et al, 2002) is that instead of one effective density, the effective density for each sub-mode is searched. This means that the search algorithm has to operate in multi-dimensional space and the result may be more sensitive to the start point than with the single mode case.…”

Section: Methods For Estimating Particle Densitymentioning

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: Methods For Estimating Particle Densitymentioning

confidence: 99%

Section: Methods For Estimating Particle Densitymentioning

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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“…113 Ristimäki et al, 114 Virtanen et al, 100 and Van Gulijk et al 101 describe how effective density can be determined using a DMA or SMPS and the ELPI and various data interpretation schemes. Virtanen et al 101 suggested that a 15% uncertainty is associated with these measurements.…”

Section: Elpi and Smpsmentioning

confidence: 99%

Alternatives to the Gravimetric Method for Quantification of Diesel Particulate Matter near the Lower Level of Detection

Swanson

Kittelson

Pui

et al. 2010

Journal of the Air & Waste Management Association

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This paper is part of the Journal of the Air & Waste Management Association's 2010 special issue on combustion aerosol measurements. The issue is a combination of papers that synthesize and evaluate ideas and perspectives that were presented by experts at a series of workshops sponsored by the Coordinating Research Council that aimed to evaluate the current and future status of diesel particulate matter (DPM) measurement. Measurement of DPM is a complex issue with many stakeholders, including air quality management and enforcement agencies, engine manufacturers, health experts, and climatologists. Adoption of the U.S. Environmental Protection Agency 2007 heavy-duty engine DPM standards posed a unique challenge to engine manufacturers. The new standards reduced DPM emissions to the point that improvements to the gravimetric method were required to increase the accuracy and the sensitivity of the measurement. Despite these improvements, the method still has shortcomings. The objectives of this paper are to review the physical and chemical properties of DPM that make gravimetric measurement difficult at very low concentrations and to review alternative metrics and methods that are potentially more accurate, sensitive, and specific. Particle volatility, size, surface area, and number metrics are considered, as well as methods to quantify them. Although the authors believe that an alternative method is required to meet the needs of engine manufacturers, the methods reviewed in the paper are applicable to other areas where the gravimetric method detection limit is approached and greater accuracy and sensitivity are required. The paper concludes by suggesting a method to measure active surface area, combined with a method to separate semi-volatile and solid fractions to further increase the specificity of the measurement, has potential for reducing the lower detection limit of DPM and enabling engine manufacturers to reduce DPM emissions in the future.

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“…Bulk particle density can be estimated from the PM chemical composition. Alternatively, effective particle density can be calculated when the following combinations are known: mobility size-aerodynamic size; mobility size-particle mass; or, aerodynamic size-particle mass (Ristimaki et al, 2002;McMurry et al, 2002). Particle water may account for some unresolved PM mass (Chow, 1995;Rees et al, 2004).…”

Section: Measurements Of Particle Density and Watermentioning

confidence: 99%

Air Quality Measurements from the Southern Particulate Matter Supersite in Taiwan

Lin

Lai

et al. 2008

Aerosol Air Qual. Res.

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This study introduces the Southern Particulate Matter Supersite in Taiwan, which began operating on April 1, 2005. The supersite has one core station and three satellite stations for monitoring the properties of particulate matter (PM) and emission sources in southern Taiwan. High-time resolution(1-30 minutes) data for physical and chemical properties of ambient PM are acquired continuously.Measurement data are as follows: (1) PM 2.5 (PM with aerodynamic diameters < 2.5 μm) and PM 10 (PM with aerodynamic diameters < 10 μm) mass concentrations; (2) PM 2.5 compositions of sulfate, nitrate and carbon; (3) particle light scattering and absorption; (4) particle number concentrations in various size fractions between 10 nm and 20 μm; (5) related precursor gases such as NO y , H 2 O 2 , and NH 3 ; and, (6) meteorological variables. Most measurements are unique to the study area and can be used to elucidate the causes of PM pollution and evaluate PM exposure and adverse health effects. In addition to describing the sampling location, measurements and data archiving, future challenges for the supersite are discussed as well.

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On-line measurement of size distribution and effective density of submicron aerosol particles

Cited by 104 publications

References 26 publications

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

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

Alternatives to the Gravimetric Method for Quantification of Diesel Particulate Matter near the Lower Level of Detection

Air Quality Measurements from the Southern Particulate Matter Supersite in Taiwan

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