2008 Progress Report: Contribution of Primary and Secondary PM Sources to Exposure & Evaluation of Their Relative Toxicity

EPA Grant Number: R832413C001
Subproject: 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.
Current Investigators: Sioutas, Constantinos , Fine, Philip M. , Geller, Michael , Hinds, William C. , Schauer, James J. , Shafer, Martin M. , Zhu, Yifang
Institution: University of Southern California , University of Wisconsin
Current Institution: University of Southern California , University of California - Los Angeles , University of Wisconsin
EPA Project Officer: Chung, Serena
Project Period: October 1, 2005 through September 30, 2010 (Extended to September 30, 2012)
Project Period Covered by this Report: October 1, 2007 through September 30,2008
RFA: Particulate Matter Research Centers (2004) RFA Text |  Recipients Lists
Research Category: Health Effects , Air

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. Our major themes are:

  1. Physical and chemical properties of PM emitted from different PM sources.
  2. Determine the characteristics of the volatile and non-volatile particle components of these sources. Also provide in vitro samples to Projects 2- 4
  3. Measure exposure gradients and intra-community variability of PM from complex, unstudied sources such as airports and port activities.
  4. To assess the contributions of these outdoor sources to indoor exposure in support of Project 4.

Approach:

State-of-the-art portable particle concentrator technologies, deployed and refined over the previous five years of the Center, allow for concentration and collection of ambient PM at multiple sites throughout the Los Angeles Basin. These sites will be purposely chosen to reflect areas impacted by the different major outdoor and indoor sources in Southern California. As will be discussed later, most of the study locations will also be sampling sites that have served the USC Childrens Health Study (CHS), providing continued linkage to that study. Advanced chemical analysis and source apportionment techniques will provide a quantitative characterization of the PM as well as the source contributions at each sampling site. In addition, state-of-the-art technologies will provide a method to measure the toxicity of PM components, including chemistry and volatility. The central hypothesis of Project 1 is that particle characteristics, which can be related to sources in terms of size and composition, determine the toxicology of PM, and variations in exposure to these characteristics according to source, season, and location influence the eventual human health response. The project consists of the following specific aims:

  1. To determine the physical and chemical properties of atmospherically processed PM emissions from real-world sources, including secondary formation, to evaluate how exposure to PM and the toxicity of PM from these sources vary with respect to location, season, and particle size, and in conjunction with Projects 2, 3 and 4 to assess their relative toxicity.
  2. To assess the contributions of these outdoor sources to indoor exposure and toxicity.
  3. To determine the physical, chemical and toxicological characteristics of the volatile and non-volatile particle components that originate from mobile sources.
  4. To measure the exposure gradients and intra-community variability of PM in complex urban areas, affected by a multitude of sources, including unstudied sources such as airports and port activities.

Progress Summary:

Over the course of the 20 months covered in this report, we carried out field sampling campaigns at the I-710, at the facilities of USC, LAX, and we completed our sampling campaign in Long Beach, CA. These studies were linked with Projects 2-4 and are described below:

Studies at the I-710

The I-710 freeway is a 26 m wide eight-lane highway connecting the ports complex of Long Beach and San Pedro to the shipping yards in East Los Angeles. For this reason, as much as 25% diesel traffic has been reported on this freeway. The I-710 study focused on particle characteristics next to the I-710 freeway and pursued the following concurrent activities:

  1. Detail chemical analysis of coarse, fine + ultrafine, and ultrafine PM including major ions, EC, OC, trace metals and organic compounds
  2. PAH and tracer concentrations and emission factors from the 710 and comparison to previous measurements in the Caldecott Tunnel
  3. In Vitro collection of coarse, fine + ultrafine, and ultrafine PM to be used by Projects 2 and 3 of this center
  4. Tandem DMA particle diameter/volatility measurements
  5. Particle surface area measurements with TSI active PM surface monitor
  6. Ultrafine mass chemical composition measurement

Activities a-f have been successfully completed and 8 manuscripts have been published, accepted or submitted for publication and provide details of these observations and analyses. In vitro PM samples have also been delivered to the investigators of Projects 2 and 3 at UCLA.

Summer Campaign at USC

This study was conducted at the University of Southern California’s Particle Instrumentation Unit (PIU) located on the University Park campus near downtown Los Angeles, California. The study was conducted over 4 consecutive 5-day weeks from June 28 through July 27, 2006. The PIU is located within ~ 150 m of a routinely congested freeway (Interstate 110) and near construction and parking facilities. Here we focus on changes occurring at a traditional “source” site. Several different aerosol measurement techniques were used to characterize the physical and chemical properties of the aerosol.

Monthly averages of the data suggest the strong influence of commute traffic emissions on morning observations of ultrafine particle concentrations. By contrast, in the afternoon our measurements provide evidence of secondary photochemical reactions becoming the predominant formation mechanism of ultrafine aerosols. Measurements of the volatility of the ultrafine aerosol are consistent with this interpretation as overall volatility increases in the afternoon and there is less evidence of external mixing. (Moore et al 2007)

During the same campaign, we focused on daily variation of ultrafine (< 180 nm in diameter) particle chemical characteristics. Ultrafine particles (UFP) were collected weekly for two 3-hr periods each day. The relative abundances of alkanes, PAH, and hopanes in the morning denote a strong influence of commute traffic emissions on ultrafine particle concentrations. By contrast, afternoon concentrations of oxygenated organic acids and sulfate rose, while other species were diluted by increased mixing height or lost due to increasing temperature. These are clear indicators that secondary photochemical reactions are a major formation mechanism of ultrafine aerosols in the afternoon. The concentrations of organic species originating from vehicular emissions measured in this study compare favorably to those from freeway-adjacent measurements by using CO2 concentrations to adjust for dilution, demonstrating the effectiveness of this tool for relating sites affected by vehicular emissions. (Ning et al 2007)

Intra-community Variability Studies

One of the major themes of Project 1 is the measurements of exposure gradients and intra-community variability of PM from complex, unstudied sources such as airports and port activities. We conducted a pilot study in the area of Long Beach, CA to investigate the intra-community spatial variation of PM impacted by numerous local and regional sources. This study shows that, although PM mass in different size fractions is spatially homogeneous within a community, the spatial distribution of some elemental components can be heterogeneous. Epidemiological studies using only PM mass concentrations from central sites may not accurately assess exposure to toxicologically-relevant PM components. (Krudysz et al 2008a, 2008b).

Indoor – Outdoor Exposure Characterization Studies (with Project 4)

In collaboration with investigators in Project 4, we measured hourly indoor and outdoor fine particulate matter (PM2.5), organic and elemental carbon (OC and EC, respectively), and particle number (PN), ozone (O3), carbon monoxide (CO), and nitrogen oxide (NOx) concentrations at two different retirement communities in the Los Angeles, CA, each during winter and summertime periods. This monitoring was part of a larger effort, the Cardiovascular Health and Air Pollution Study (CHAPS), which is also supported by the activities of Project 4. Overall, the magnitude of indoor and outdoor measurements was similar, probably because of the major influence of outdoor sources on indoor particle and gas levels. On average, 36% - 44% of measured indoor OC was composed of outdoor-generated primary OC. contributions of outdoor-generated SOA and primary OC to indoor OC and to demonstrate their importance in indoor environments. The outcomes presented here will be used by CHAPS investigators to determine the relationship between cardiovascular outcomes and hourly retirement community exposures by each resident to PM2.5 of indoor and outdoor origin. (Polidori et al 2007)

Los Angeles – Long Beach Port Studies

During our winter campaign (Arhami et al 2008), PM samples were collected concurrently at six sites for a 7-weeks period between February and May 2007. Four sites were set-up within the communities of Wilmington and Long Beach; one site was located at a background location near the harbors of the Los Angeles port; the sixth site, near downtown Los Angeles, was chosen to represent a typical urban area. Coarse (PM2.5-10), accumulation (PM0.25-2.5), and quasi-ultrafine (PM0.25) mode particles were collected at each site. Vehicular emissions from the nearby traffic were the most prominent anthropogenic sources of both quasi-ultrafine and accumulation mode PM in all port sites (except at the background site located upwind, where ship emissions were the dominant PM source). Overall, traffic sources were major contributors to the PM and organic matter mass, and prevailed over ship emissions and oil combustion even in the studied harbor community. (Arhami et al 2008)

In collaboration with investigators from projects 2-3, we have also examined the ability of PM in that area to induce oxidative stress (Hu et al 2008). The formation of reactive oxygen species (ROS) in cells exposed to particulate matter (PM) results in oxidative stress, which is an important mechanism associated with many adverse health effects caused by PM exposure. The results confirmed our earlier observations that OC (mostly from motor-vehicle emissions) is the most important component influencing the DTT consumption by PM samples. The variability of macrophage ROS was better explained by variations in OC concentrations and water-soluble vanadium (probably from ship emissions – bunker oil combustion). (Hu et al 2008)

In order to better understand and quantify intra-community variability in UFP concentrations in the complex area of the LA- Long Beach port, a dense network of 14 monitoring sites was set-up in Los Angeles in two clusters – San Pedro/Wilmington and West Long Beach – in communities surrounding the Ports of Los Angeles and Long Beach. The intra-urban variability observed in this study is comparable to and exceeds the inter-urban variability observed in a previous study in Los Angeles. UFP concentrations can vary considerably on short spatial scales in source-rich environments, which can strongly influence the accuracy of exposure assessments (Moore et al 2008). In addition to the particle number concentration measurements described above, we conducted concurrent particle size distribution measurements in an effort to identify UFP sources and types in the LA – Long Beach port area, while providing data to investigate local scale effects of both photochemical and physical processes on UFP. Spatial heterogeneity exists between “background” and “source” sites especially for particles < 40 nm, while spatial homogeneity is observed between geographically close sites. In addition, variations in r-values as a function of particle size are not necessarily consistent with corresponding CODs values, indicating that using results from correlation analysis alone may not accurately assess spatial variability. This study is described in detail by Krudysz et al (2008b).

Los Angeles Airport (LAX) Pilot Study

During this period, we also completed the data analysis and publication of our first pilot studies at LAX (see Westerdahl et al 2008). Air monitoring was performed in the vicinity of the Los Angeles International Airport (LAX) during the spring of 2006. The particle numbers at the upwind site were dominated by particles of approximately 90 nm diameter while downwind sites were dominated by particles peaking at approximately 10-to-15 nm. Additional data obtained from a study of UFP levels conducted subsequently by a co-author indicates that aircraft-generated UFP persist up to 900 meters from an LAX runway (Biswas et al 2007). Considered together, these observations suggest that airport operations are associated with elevated levels of UFP much further downwind in the neighboring community than would have been predicted by prior studies of UFP from roadway-traffic. Based on these results, we intend to conduct at a later time more detailed studies in that area, focusing this time on the collecting of ultrafine and accumulation mode particles for chemical and toxicological analysis in the same locations of the Westerdahl et al (2008) study.

Reconciling Emission Factors of PM Species Emitted by Vehicles in Freeways and Roadway Tunnel Environments

In addition to our tunnel-based emission factors for light and heavy duty vehicles, we estimated emission factors of various particle species from light and heavy duty vehicles (LDVs and HDVs, respectively), including organic and elemental carbon (OC and EC,), sulfate, polycyclic aromatic hydrocarbons (PAHs), hopanes, steranes, trace metals, elements, and particle number (PN), based on roadway measurements (Ning et al 2008). Sampling campaigns were conducted at two different roadways: the CA-110 highway (where only gasoline-powered vehicles are allowed), and the I-710 freeway (where about 20% of the total number of vehicles are diesel-powered trucks). The PM emission factors determined in these roadways were compared to those reconstructed from recent source emission data from the Caldecott tunnel (Phuleria et al 2006), and those from previous tunnel and chassis dynamometer studies. Very good agreement between estimated and reconstructed emission factors was found. This suggests that PM speciated chemical data collected at roadsides can be used to calculate reliable emission factors for several important particulate species at other locations, characterized by a similar mix of on-road motor vehicles. Thus, it may be plausible to estimate the concentration of organic tracers next to the freeway by averaging emission profiles of different vehicles and driving cycles measured on a dynamometer if the dilution factor (typically calculated based on CO2 concentrations) between dynamometer and the freeway is known or can be determined. (Ning et al 2007). Based on these roadway measurements and average driving time, it appears that 33–45% of total UFP exposure for Los Angeles residents occurs due to time spent traveling in vehicles. (Fruin et al 2008)

Physicochemical and toxicological properties of Particulate Matter from October 2007 Southern California wildfires (collaboration with Project 3 and Dr. Flemming Cassee)

Wood smoke is one of the important sources of PM whose chemistry and toxicity we proposed to investigate. On October 20, 2007, 23 large wildfires ranging from Santa Barbara County to the U.S.– Mexico border, burned more than 500,000 acres of land and destroyed over 1,500 homes with the largest mandatory evacuation (of over 900,000 people) in the state's history. During this period, we conducted measurements of various particle and gaseous pollutants such as CO, nitrogen oxides, O3, PM2.5 (particles with an aerodynamic diameter less that 2.5 µm) mass with its chemical constituents, and size fractionated particle number, measured at a site near the University of Southern California (USC). Detailed chemical and toxicological characteristics have been evaluated from the PM samples collected during the fire event, and compared to those after the October 2007 fire period (when outdoor PM2.5 is mostly impacted by the vehicular traffic emissions). We showed that concentration of water-soluble organic carbon (WSOC) and several organic tracers including levoglucosan were increased by 2-3 fold during the fire period. The per mass PM toxicity expressed in nmoles of DTT consumed per μg of PM and min was also higher for the samples collected during the wildfire episode compared to the PM samples impacted by traffic suggesting that wood smoke on a per PM mass basis is a significant source of PM that are redox active. (Verma et al 2008).

Health Studies – collectively with Project 2 :The Role of Oxidative Stress in the Susceptibility to PM-Induced Adverse Health Effects

During this period covered by this report, we have assisted the investigators of project 2 to conduct exposures of genetically susceptible (apoE-deficient) mice to well characterized (physically and chemically) fine and ultrafine CAPs. Following up on the results of the Campbell et al (2008) study, we have further explored the evidence that the brain may also constitute a site adversely effected by the environmental presence of airborne particulate matter by examining the association between exposure to PM and adverse CNS effects in apolipoprotein E knockout (ApoE-/-) mice exposed to two levels of concentrated ultrafine particulate matter in central Los Angeles (USC) using our concentrators. The study provided clear evidence of aberrant immune activation in the brains of exposed animals as judged by a dose-related increase in nuclear translocation of two key transcription factors, NF-kB and AP-1. In order to determine the mechanism by which these events occurred, levels of several MAP kinases involved in activation of these transcription factors were assayed by Western blotting. The results suggest that the signaling pathway by which these transcription factors are activated involves the activation of JNK. (Kleinman et al 2008)

Development of high collection efficiency electrostatic precipitator for in vitro cell exposure to concentrated ambient particulate matter (PM)- projects 2-3

In several discussions with ESAC members (Drs. Flagan, McMurry, Russell and Cassee) over the past year and during our previous meetings, we entertained the idea of utilizing electrostatic precipitation for on-line collections of PM for toxicity studies. To that end, we developed a new sampling system to collect ambient particles for in-vitro studies (Sillanpaa et al 2008). The in-vitro electrostatic collector consists of two units: a Versatile Aerosol Concentration Enrichment System (VACES) and a new design of electrostatic precipitator (ESP). This system allows for shorter sampling durations, which benefits cells that might not be viable after prolonged exposure to the sampling environment. Shorter time interval sampling also enables discovery of possible relationships between health effects and time of day or short-term source emissions. The main advantage of in-vitro electrostatic collector is that it collects >95% of particles - regardless of particle type or diameter - directly to a target area, on which a cell culture can be placed. The unique design implements two metal needles to facilitate a corona discharge, resulting in high particle charging efficiency with little ozone production. These advantages make the in-vitro electrostatic collector a viable in-vitro cell exposure technique.

Novel Zero- Ozone Unipolar Charging of Ultra-fine Aerosol Particles using Carbon Fiber Ionizers

Expanding further our technology and use of ESPs for in vitro PM collections, we replaced the unipolar corona discharge charger of our ESP with a simple and novel unipolar charger using carbon fiber ionizers (Han et al 2008a). This charger was developed to effectively charge ultra-fine aerosol particles without the generation of ozone. The newly developed unipolar charger using carbon fiber ionizers can charge ultra-fine particles at least as effectively as currently available unipolar chargers, but with the major advantage of negligible ozone generation, a highly desirable feature if the charged particles are to be used for chemical or biological analysis. (Han et al 2008b)

Health Studies with Project 3: Chemical Reactivity of Particulate Matter Sources, and Modification of Chemical and Cellular Properties of PM-Associated Components by the Particle Matrix

In a collaborative study with investigators from projects 3 and 4, we have collected using our VACES fine and ultrafine PM in the area of Riverside and in one of the retirements homes of the subjects of the study in Project 4, to assist our colleagues in their efforts to develop an analytical procedure to detect electrophiles that can be applied to the study of air pollution samples, using the active site of the thiol enzyme, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (EC 1.2.1.12) as the target nucleophile.

Health Studies with Project 4: Oxidative Stress Reponses to PM Exposure in Elderly Individuals with Coronary Heart Disease

In collaboration with investigators in Project 4, we explored the association between circulating biomarkers of inflammation, antioxidant activity, and platelet activation with primary combustion and secondary aerosols among the study subjects of that project. Our results suggest traffic emission sources of primary OC and quasi-ultrafine particles lead to increases systemic inflammation and platelet activation, and decreases in antioxidant enzyme activity in elderly people with coronary artery disease. (Delfino et al 2008b)

Expected Results:

This project will provide valuable insight into the source-exposure-response continuum outlined by the National Research Council (NRC, 2004) by developing fundamental understanding on the links between specific sources and adverse toxicological outcomes associated with exposure to PM. The information generated by this project will serve as the basis for linking emissions to local air quality and ultimately to health effects. By providing a wide range of exposure parameters for the toxicological studies described in Projects 2, 3 and 4, the toxicity of different sources and exposure scenarios can be assessed. Knowing the relative toxicity of atmospherically processed PM emissions from real-world sources will allow for more targeted and effective regulatory strategies. These data on which PM sources are the most toxic, combined with detailed chemical and physical characterization of PM from these sources will allow for a narrower, more focused effort in identifying the biological mechanisms of PM health effects (as described in Projects 2, 3 and 4).

Future Activities:

In the next year of our activities, we will continue our efforts towards the completion of the following activities:

  1. Use the Chemical Mass Balance (CMB) model and our organic tracers’ data to do source apportionment in the LA-Long Beach harbor sites for PM2.5 as well as for ultrafine particles. We will also examine the seasonal variability of these chemical species and the differences in the contribution of sources between winter and summer seasons.
  2. Our Ning Z. et al, Environmental Science and Technology, 41 (17),6000-6006, 2007 paper identified clearly two distinctly different time periods in the summertime at USC; once impacted by vehicular emissions and the other by secondary formation processes. We will conduct high volume collections (order of 10 mg) of ultrafine and accumulation mode PM during these two periods at USC for in vitro toxicological analysis, thus coupling the chemical work performed by our group previously with toxicological outcomes. These samples will be used by investigators in projects 2 and 3 and will serve as pilot data to a more ambitious study (the trajectory study) that we intend to carry out during the 4th year of our program.
  3. We will thus attempt to address the limitations of current state-of-the-art in ultrafine particle charging discussed above by coupling the Versatile Aerosol Concentration Enrichment System (VACES) with the unipolar charger using carbon fiber ionizers that we developed (Han et al 2008a). Our goal is to prove that this is a promising alternative for particle charging, especially in applications involving sampling and collection of atmospheric aerosols, often rich in organic compounds, which could be degraded by reactions with ozone and other radicals produced by corona chargers.
  4. Exposure assessment analysis in support of the health investigations of Project 4, which is described in more detail in the summary for Project 4.


Journal Articles on this Report : 29 Displayed | Download in RIS Format

Other subproject views: All 87 publications 85 publications in selected types All 85 journal articles
Other center views: All 241 publications 157 publications in selected types All 157 journal articles
Type Citation Sub Project Document Sources
Journal Article Araujo JA, Barajas B, Kleinman M, Wang X, Bennett BJ, Gong KW, Navab M, Harkema J, Sioutas C, Lusis AJ, Nel AE. Ambient particulate pollutants in the ultrafine range promote early atherosclerosis and systemic oxidative stress. Circulation Research 2008;102(5):589-596. R832413 (2008)
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  • Journal Article Ayres JG, Borm P, Cassee FR, Castranova V, Donaldson K, Ghio A, Harrison RM, Hider R, Kelly F, Kooter IM, Marano F, Maynard RL, Mudway I, Nel A, Sioutas C, Smith S, Baeza-Squiban A, Cho A, Duggan S, Froines J. Evaluating the toxicity of airborne particulate matter and nanoparticles by measuring oxidative stress potential—a workshop report and consensus statement. Inhalation Toxicology 2008;20(1):75-99. R832413 (2008)
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  • Journal Article 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)
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  • Journal Article Delfino RJ, Staimer N, Tjoa T, Gillen D, Kleinman MT, Sioutas C, Cooper D. Personal and ambient air pollution exposures and lung function decrements in children with asthma. Environmental Health Perspectives 2008;116(4):550-558. R832413 (2007)
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  • Journal Article Delfino RJ, Staimer N, Tjoa T, Polidori A, Arhami M, Gillen DL, Kleinman MT, Vaziri ND, Longhurst J, Zaldivar F, Sioutas C. Circulating biomarkers of inflammation, antioxidant activity, and platelet activation are associated with primary combustion aerosols in subjects with coronary artery disease. Environmental Health Perspectives 2008;116(7):898-906. R832413 (2007)
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  • Journal Article Fruin S, Westerdahl D, Sax T, Sioutas C, Fine PM. Measurements and predictors of on-road ultrafine particle concentrations and associated pollutants in Los Angeles. Atmospheric Environment 2008;42(2):207-219. R832413 (2008)
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  • Journal Article Gong Jr. H, Linn WS, Clark KW, Anderson KR, Sioutas C, Alexis NE, Cascio WE, Devlin RB. Exposures of healthy and asthmatic volunteers to concentrated ambient ultrafine particles in Los Angeles. Inhalation Toxicology 2008;20(6):533-545. R832413 (2007)
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  • Journal Article Gong KW, Zhao W, Li N, Barajas B, Kleinman M, Sioutas C, Horvath S, Lusis AJ, Nel A, Araujo JA. Air-pollutant chemicals and oxidized lipids exhibit genome-wide synergistic effects on endothelial cells. Genome Biology 2007;8(7):R149 (13 pp.). R832413 (2008)
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  • Journal Article Han B, Hudda N, Ning Z, Sioutas C. Enhanced unipolar charging of concentration-enriched particles using water-based condensational growth. Journal of Aerosol Science 2008;39(9):770-784. R832413 (2009)
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  • Journal Article Kleinman MT, Sioutas C, Froines JR, Fanning E, Hamade A, Mendez L, Meacher D, Oldham M. Inhalation of concentrated ambient particulate matter near a heavily trafficked road stimulates antigen-induced airway responses in mice. Inhalation Toxicology 2007;19(Suppl 1):117-126. R832413 (2008)
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  • Journal Article Kleinman MT, Araujo JA, Nel A, Sioutas C, Campbell A, Cong PQ, Li H, Bondy SC. Inhaled ultrafine particulate matter affects CNS inflammatory processes and may act via MAP kinase signaling pathways. Toxicology Letters 2008;178(2):127-130. R832413 (2007)
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  • Journal Article Majestic BJ, Schauer JJ, Shafer MM, Fine PM, Singh M, Sioutas C. Trace metal analysis of atmospheric particulate matter: a comparison of personal and ambient samplers. Journal of Environmental Engineering and Science 2008;7(4):289-298. R832413 (2007)
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  • Journal Article Moore KF, Ning Z, Ntziachristos L, Schauer JJ, Sioutas C. Daily variation in the properties of urban ultrafine aerosol—Part I:physical characterization and volatility. Atmospheric Environment 2007;41(38):8633-8646. R832413 (2008)
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  • Journal Article Ning Z, Moore KF, Polidori A, Sioutas C. Field validation of the new miniature Versatile Aerosol Concentration Enrichment System (mVACES). Aerosol Science and Technology 2006;40(12):1098-1110. R832413 (2007)
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  • Journal Article Ning Z, Geller MD, Moore KF, Sheesley R, Schauer JJ, Sioutas C. Daily variation in chemical characteristics of urban ultrafine aerosols and inference of their sources. Environmental Science & Technology 2007;41(17):6000-6006. R832413 (2008)
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  • Journal Article Ning Z, Polidori A, Schauer JJ, Sioutas C. Emission factors of PM species based on freeway measurements and comparison with tunnel and dynamometer studies. Atmospheric Environment 2008;42(13):3099-3114. R832413 (2007)
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    R832413C001 (2007)
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  • Journal Article 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)
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  • Journal Article Ntziachristos L, Froines JR, Cho AK, Sioutas C. Relationship between redox activity and chemical speciation of size-fractionated particulate matter. Particle and Fibre Toxicology 2007;4:5 (12 pp.). R832413 (2008)
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  • Journal Article Ntziachristos L, Ning Z, Geller MD, Sheesley RJ, Schauer JJ, Sioutas C. Fine, ultrafine and nanoparticle trace element compositions near a major freeway with a high heavy-duty diesel fraction. Atmospheric Environment 2007;41(27):5684-5696. R832413 (2007)
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  • Journal Article 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)
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  • Journal Article Phuleria HC, Sheesley RJ, Schauer JJ, Fine PM, Sioutas C. Roadside measurements of size-segregated particulate organic compounds near gasoline and diesel-dominated freeways in Los Angeles, CA. Atmospheric Environment 2007;41(22):4653-4671. R832413 (2008)
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  • Journal Article Polidori A, Arhami M, Sioutas C, Delfino RJ, Allen R. Indoor/outdoor relationships, trends, and carbonaceous content of fine particulate matter in retirement homes of the Los Angeles Basin. Journal of the Air & Waste Management Association 2007;57(3):366-379. R832413 (2008)
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  • Journal Article Polidori A, Hu S, Biswas S, Delfino RJ, Sioutas C. Real-time characterization of particle-bound polycyclic aromatic hydrocarbons in ambient aerosols and from motor-vehicle exhaust. Atmospheric Chemistry and Physics 2008;8(5):1277-1291. R832413 (2007)
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  • Journal Article Shinyashiki M, Rodriguez CE, Di Stefano EW, Sioutas C, Delfino RJ, Kumagai Y, Froines JR, Cho AK. On the interaction between glyceraldehyde-3-phosphate dehydrogenase and airborne particles:evidence for electrophilic species. Atmospheric Environment 2008;42(3):517-529. R832413 (2008)
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  • Journal Article Sillanpaa M, Geller MD, Phuleria HC, Sioutas C. High collection efficiency electrostatic precipitator for in vitro cell exposure to concentrated ambient particulate matter (PM). Journal of Aerosol Science 2008;39(4):335-347. R832413 (2007)
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  • Journal Article Snyder DC, Dallmann TR, Schauer JJ, Holloway T, Kleeman MJ, Geller MD, Sioutas C. Direct observation of the break-up of a nocturnal inversion layer using elemental mercury as a tracer. Geophysical Research Letters 2008;35(17):L17812. R832413 (2008)
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  • Journal Article Westerdahl D, Fruin SA, Fine PL, Sioutas C. The Los Angeles International Airport as a source of ultrafine particles and other pollutants to nearby communities. Atmospheric Environment 2008;42(13):3143-3155. R832413 (2007)
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    R831861 (2005)
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  • Journal Article Xia T, Kovochich M, Brant J, Hotze M, Sempf J, Oberley T, Sioutas C, Yeh JI, Wiesner MR, Nel AE. Comparison of the abilities of ambient and manufactured nanoparticles to induce cellular toxicity according to an oxidative stress paradigm. Nano Letters 2006;6(8):1794-1807. R832413 (2008)
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    R827352C002 (Final)
    R827352C014 (Final)
  • Abstract from PubMed
  • Full-text: UCLA-Full Text PDF
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  • Journal Article Yacobi NR, Phuleria HC, Demaio L, Liang CH, Peng C-A, Sioutas C, Borok Z, Kim K-J, Crandall ED. Nanoparticle effects on rat alveolar epithelial cell monolayer barrier properties. Toxicology in Vitro 2007;21(8):1373-1381. R832413 (2008)
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  • Supplemental Keywords:

    PM, sources, toxicity, apportionment, ultrafine, semi-volatile, RFA, Health, Scientific Discipline, Air, particulate matter, Health Risk Assessment, Risk Assessments, Biochemistry, Ecology and Ecosystems, atmospheric particulate matter, particulates, human health effects, PM 2.5, chemical characteristics, toxicology, airway disease, airborne particulate matter, cardiovascular vulnerability, air pollution, human exposure, vascular dysfunction, cardiovascular disease, human health risk

    Progress and Final Reports:

    Original Abstract
  • 2006 Progress Report
  • 2007 Progress Report
  • 2009 Progress Report
  • 2010 Progress Report
  • 2011
  • Final 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