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2006 Progress Report: Contribution of Primary and Secondary PM Sources to Exposure & Evaluation of Their Relative Toxicity
EPA Grant Number: R832413C001Subproject: this is subproject number 001 , established and managed by the Center Director under grant R832413
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: Southern California Particle Center
Center Director: Froines, John R.
Title: Contribution of Primary and Secondary PM Sources to Exposure & Evaluation of Their Relative Toxicity
Investigators: Sioutas, Constantinos , Schauer, James J.
Institution: University of Southern California , University of California - Los Angeles , University of Wisconsin
Current Institution: University of Southern California , University of Wisconsin
EPA Project Officer: Katz, Stacey
Project Period: October 1, 2005 through September 30, 2010
Project Period Covered by this Report: October 1, 2005 through September 30, 2006
Project Amount: Refer to main center abstract for funding details.
RFA: Particulate Matter Research Centers (2004)
Research Category: Particulate Matter
Description:
Objective:The primary objective of Project 1 is to examine the relationships between PM sources, exposure, and toxicity within the constraints of the urban atmosphere. This project is an integral part of Projects 2, 3 and 4, by serving as the field operations to collect PM samples for toxicity testing and for providing elevated levels of ambient PM for animal exposure models described in these projects.
Progress Summary:Over the course of the first 6 months of this effort, and in concert with our proposed scope of work, we carried out field sampling campaigns at the I-710 (February–April 2006) and at the facilities of USC (June 2006–present).
The I-710 freeway is a 26 m wide eight-lane highway connecting the Long Beach and San Pedro port complexes to the shipping yards in East Los Angeles. I-710 has the highest ratio (up to 25%) of heavy-duty diesel vehicles in the Los Angeles highway network (http://traffic-counts.dot.ca.gov 
). Total traffic counts on this freeway are very high: between 150,000–200,000 vehicles per day pass the sampling location. The sampling site was located in a paved property run by the Imperial Flood Control Yard in South Gate, CA. At the I-710 we pursued the following concurrent activities:
- Hi-volume filter collections of coarse, fine + ultrafine, and ultrafine PM
- PAH and tracer concentrations and emission factors from the 710
- In vitro collection of coarse, fine + ultrafine, and ultrafine PM to be used by Projects 2 and 3 of this Center
- Tandem DMA particle diameter/volatility measurements
- Particle surface area measurements with TSI, Inc., active PM surface monitor
- Ultrafine mass chemical composition measurement.
Activities (1-5) have been successfully completed and 3 manuscripts have been submitted for publication, described below. Chemical analysis of the collected PM samples is being conducted and results will become available by the end of August 2006. In vitro PM samples have been delivered to the investigators of Projects 2 and 3 at UCLA.
As noted above, particle concentration measurements at I-710 were accompanied by measurements of black carbon, elemental and organic carbon and gaseous species (CO, CO2). Using the incremental increase of CO2 over the background as an indication of the dilution ratio, it is possible to compare particle concentrations measured by the freeway to concentrations measured in roadway tunnels and in the laboratory. A principal component analysis showed that the volume of the accumulation mode (40-640 nm) is positively correlated with the black carbon concentration, which provides evidence of the diesel truck impact on that PM size range, while the volume of nucleation mode (16-40 nm) mostly depends on ambient conditions and increases in the evening as the temperature and the ambient mixing layer decrease. In addition, multivariate regressions showed that light and heavy organic carbon concentrations are positively correlated with the particle volume in the nucleation and accumulation modes respectively. The results of this study may be used to predict the effect of vehicle technology and ambient condition variations on particle size distribution and concentration next to major freeways.
During the same sampling campaign at the I-710, we investigated the volatility of ambient particles of 20, 40, 80 and 120 nm in diameter using a Tandem Differential Mobility Analyzer (TDMA) at two locations: close to the freeway (10 m) and approximately 150 m downwind. The smallest particles (20 nm) are mostly volatile at both locations. Larger particles (e.g., ≥ 40 nm) showed evidence of external mixing, with the nonvolatile fraction increasing with particle size. Particle volatility increased with decreasing ambient temperature. The HDDVs contribute to relatively larger nonvolatile particle number and volume fractions and greater external mixing than earlier observations at a pure light-duty gasoline vehicle freeway (Kuhn, et al. Atmospheric Environment 2005;39:7154). Finally, the fraction of externally mixed soot particles decreased as the downwind distance increased from the I-710, due to atmospheric processes such as vapor adsorption, condensation and coagulation.
Particle surface area has been considered a particle characteristic relevant to health effects. In order to provide input to health effects studies, two similar Nanoparticle Surface Area Monitors (NSAMs, TSI, Inc.) were deployed in different urban sites within Los Angeles to monitor concentration levels and diurnal profiles of the surface area of ambient particles. The NSAM’s principle of operation is based on the unipolar diffusion charging of atmospheric particles. Results show that the surface area concentration decreases from ~150 μm2/cm3 next to the freeway to ~100 μm2/cm3 at 100 m downwind of the freeway and then to 50-70 μm2/cm3 at urban background sites. Next to the freeway, up to 51% of the total surface area corresponded to particles < 40 nm. This decreased to 30% at urban background sites. The NSAM signal was found to adequately correlate with a reconstructed surface concentration based on the particle number size distribution measured with collocated Scanning Mobility Particle Sizers (SMPSs, TSI, Inc.). In addition, the mean surface-weighted particle diameter calculated by combination of the NSAM and the total particle number concentration measured by a Condensation Particle Counter (CPC, TSI, Inc.) was found to satisfactorily agree with the arithmetic mean SMPS diameter. This study corroborates earlier findings on the application of diffusion chargers for ambient particle monitoring by demonstrating that they can be effectively used to monitor surface area concentration, or combined with a CPC to derive a mean surface-weighted particle diameter in very short time periods.
Future Activities:In the next phase of this project, we will complete all chemical analysis of the collected size fractionated PM in the I-710 and at USC. In collaboration with Dr. Schauer and his group, we intend to submit at least 2 manuscripts for publication in the peer reviewed literature. In the first paper, we will describe the size fractionated chemical speciation of PM collected in the vicinity of the I-710 freeway. The second paper will describe the source signature of a high-diesel traffic freeway for three sizes of PM emissions, with respect to individual organic compounds and elemental composition. The coarse mode will represent a heavy-duty road dust sample. These measurements will also be compared to our previous work in the Caldecott tunnel (Phuleria HC, Geller MD, Fine PM, Sioutas C*. Size-resolved emissions of organic tracers from light and heavy-duty vehicles measured in a California roadway tunnel. Environmental Science & Technology 2006;40:4109-4118). Further sampling campaigns will follow the plan developed in our technical proposal for the grant.
Journal Articles on this Report: 3 Displayed | Download in RIS Format
| Other subproject views: | All 36 publications | 35 publications in selected types | All 34 journal articles |
| Other center views: | All 94 publications | 48 publications in selected types | All 47 journal articles |
| Type | Citation | ||
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Biswas S, Ntziachristos L, Moore KF, Sioutas C. Particle volatility in the vicinity of a freeway with heavy-duty diesel traffic. Atmospheric Environment 2007;41(16):3479-3493. |
R832413 (2008) R832413C001 (2006) R832413C001 (2007) R832413C001 (2008) |
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Ntziachristos L, Polidori A, Phuleria H, Geller MD, Sioutas C. Application of a diffusion charger for the measurement of particle surface concentration in different environments. Aerosol Science and Technology 2007;41(6):571-580. |
R832413 (2008) R832413C001 (2006) R832413C001 (2007) R832413C001 (2008) |
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Ntziachristos L, Ning Z, Geller MD, Sioutas C. Particle concentration and characteristics near a major freeway with heavy-duty diesel traffic. Environmental Science & Technology 2007;41(7):2223-2230. |
R832413 (2008) R832413C001 (2006) R832413C001 (2007) R832413C001 (2008) |
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PM, sources, toxicity, apportionment, ultrafine, semi-volatile,
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Air, Scientific Discipline, Health, RFA, Risk Assessments, Health Risk Assessment, Biochemistry, particulate matter, Ecology and Ecosystems, cardiovascular disease, cardiovascular vulnerability, chemical characteristics, human health risk, oxidative stress, human health effects, particulates, PM 2.5, toxicology, air pollution, airway disease, atmospheric particulate matter, vascular dysfunction, airborne particulate matter
Relevant Websites:
Progress and Final Reports:
Original Abstract
2007 Progress Report
2008 Progress Report
Main Center Abstract and Reports:
R832413 Southern California Particle Center
Subprojects under this Center:
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R832413C001 Contribution of Primary and Secondary PM Sources to Exposure & Evaluation of Their Relative Toxicity
R832413C002 Project 2: The Role of Oxidative Stress in PM-induced Adverse Health Effects
R832413C003 The Chemical Properties of PM and their Toxicological Implications
R832413C004 Oxidative Stress Responses to PM Exposure in Elderly Individuals With Coronary Heart Disease
R832413C005 Ultrafine Particles on and Near Freeways