2010 Progress Report: Sources, Composition, Variability and Toxicological Characteristics of Coarse (PM10-2.5) Particles in Southern California

EPA Grant Number: R833743
Title: Sources, Composition, Variability and Toxicological Characteristics of Coarse (PM10-2.5) Particles in Southern California
Investigators: Sioutas, Constantinos , Cho, Arthur K. , Froines, John R. , Geller, Michael , Nel, Andre E. , Schauer, James J.
Current Investigators: Sioutas, Constantinos , Cho, Arthur K. , Froines, John R. , Moore, Katharine F. , Nel, Andre E. , Schauer, James J.
Institution: University of Southern California , University of California - Los Angeles , University of Wisconsin - Madison
EPA Project Officer: Chung, Serena
Project Period: November 1, 2007 through October 31, 2009 (Extended to October 31, 2012)
Project Period Covered by this Report: November 1, 2009 through October 31,2010
Project Amount: $1,120,641
RFA: Sources, Composition, and Health Effects of Coarse Particulate Matter (2006) RFA Text |  Recipients Lists
Research Category: Air , Air Quality and Air Toxics , Particulate Matter

Objective:

The objective of this study is to provide the much-needed information on the relationships between coarse particulate matter (PM) sources, spatial and seasonal characteristics, and toxicity in Southern California. The multidisciplinary research currently underway combines ambient measurements, exposure assessment, and toxicology. The results of this study – the Los Angeles Basin (LAB) Coarse PM Study – will be integrated with other major research efforts currently under way in Southern California, including the EPA-funded Southern California PM Center.

Progress Summary:

During Year 1, we performed the following tasks:

  • Designed, assembled, tested, and deployed 10 outdoor coarse PM samplers to the field to collect the time-integrated filter samples across the Los Angeles Basin. Field sampling campaign commenced in April 2008 (Q2) and the weekly collection of coarse PM samples, each integrated of 24 hours sampling time, continued uninterruptedly until May 2009 (the end of Q2).
  • Designed, assembled, tested, and deployed two indoor coarse PM samplers to the field to collect the indoor filter samples in two indoor sites associated with their corresponding outdoor sites. Phase I of the indoor sampling started in mid-July 2008 (Q3) and continued successfully for 9 consecutive weeks through early September 2008 (Q4). Collection of a single 24-hour integrated weekly sample was carried out concurrently with the operation of the associated outdoor coarse PM sampler.
  • Following factory recalibration and testing at USC, three tapered element oscillating microbalance (TEOM) units modified to measure coarse PM only were deployed to sampling sites in Riverside, Lancaster, and downtown Los Angeles to provide continuous hourly data of ambient coarse PM concentration. Deployment commenced during April and May 2008 (Q2) and measurements continued through the end of the campaign.
  • Detailed field sampling maintenance protocols were developed for the collection of both the time-integrated filter samples and continuous data for the regular weekly visit to each site.
  • Supporting hourly air quality data (e.g., meteorological parameters) were acquired for each coarse PM sampling site covering the period of concurrent time-integrated filter sampling from Q2 of 2008 through Q2 of 2009.
  • The mass concentration of each filter was determined by the gravimetric measurement of the filters in sampling each site on an ongoing basis.

During Year 2, we performed the following tasks:

  • Completed the collection of weekly 24-hr integrated filter samples starting from early-April 2008 (Q2) to end of May 2009 (14 months). The coarse PM samplers at all the sites except sites in Los Angeles, Lancaster, and Riverside were disassembled. The three samplers in the aforementioned sites were modified and designated for the intensive coarse PM sampling campaign.
  • Designed, assembled, tested, and deployed the coarse PM samplers to the field using an additional set of USC virtual impactor (VI) samplers for winter and summer intensive campaigns in 3 of the 10 sites representing distinct regions of the Los Angeles Basin. The purpose of the intensive campaign is to collect samples in four distinct daily time periods to assess the diurnal variations in coarse PM concentrations and chemical composition. Phase 1 of the intensive campaign started in mid-July 2009 (Q3) and continued successfully for 5 consecutive weeks through late August 2009 at three locations.

QA/QC was performed on the continuous and time-integrated measurements (including measurements from intensive campaign) based primarily on the mass concentration data reported for each filter. Comparisons between the continuous and time-integrated data also helped to identify problematic data. > 88% of all collected filter samples passed QA/QC and were submitted for chemical and biological analysis.

During Year 3, we performed the following tasks:

  • The second phase of intensive campaign started in mid-January 2010 (Q1) and continued for 6 consecutive weeks.
  • All sample substrates were distributed between University of California-Los Angeles and University of Wisconsin-Madison for chemical and biological analysis.
  • The data processing started promptly after a complete data set for one year of the study was received.

Preliminary Results

The time-integrated mass concentration results indicate that ambient coarse PM varies from 0.5 µg/m3 to more than 35 µg/m3 at the 10 sites in the Los Angeles Basin. Mean 24-hour coarse PM concentrations at all sites are typically 10 µg/m3 with the exception of Lancaster site, where the average concentration is about one-half (5 µg/m3). Summer concentrations were typically 2 to 4 times higher than the winter concentrations at most sites. However summer concentrations in Long Beach were lower than in the winter. Concentrations derived from both of the samplers (PCIS and USC VI) were compared to each other at 9 of the 10 outdoor monitoring sites. Agreement in the coarse PM concentrations produced by these two samplers is very reasonable (within 15% on average) with PCIS concentrations typically lower.

CPM concentration correlations between different sites reveal similar trends of CPM concentrations in nearby sites. The Long Beach site, which is located in the “source” regions of the Los Angeles Basin, had weak correlations with other sites, while strong correlations were observed among the urban Los Angeles sites. Correlations between measured CPM and PM2.5 were investigated. PM2.5 particles are produced predominantly from vehicular emissions and high correlations indicate that the dominant source of coarse particles is traffic-induced resuspended PM in urban areas, where correlations were relatively higher. The relatively lower correlations in rural sites indicate that wind-blown dust is the significant contributor to CPM concentrations. Correlation of CPM and PM2.5 concentrations are much higher during winter than summer highlighting the increasing role of windblown dust in windier and dryer months in summer.

To characterize the chemical composition of coarse particles, chemical constituents are divided into 5 major categories: 1) crustal materials and trace elements; 2) organic matter; 3) elemental carbon; 4) sea salts; and 5) secondary ions. Overall, crustal materials and trace elements were the most dominant sources of coarse PM in this Basin, followed by secondary ions and organic matter. In particular, nitrate was the most abundant inorganic species, accounting for more than 17% of total reconstructed mass. Concentrations of elemental carbon were low in the coarse mode, with an average mass fraction of less than 2% across sites. Higher concentrations of sea salt were observed at the coastal sites, while crustal materials became dominant inland. The two Riverside sites experienced higher levels of organic matter, probably generated from the nearby agricultural area. Interestingly, OC was found to be highly correlated with soil dust tracers, suggesting that organic materials and mineral dust might share common origins or that organic materials might be present on the surface of mineral dust particles in the coarse mode.

The abundance and the spatial and temporal behavior of metals in coarse fraction of atmospheric particulate matter (CPM, particles smaller than 10 and larger than 2.5 µm in diameter, PM10-2.5) were studied in the Los Angeles area. Major trace element and metal sources contributing to CPM may consist of (but not limited to) re-suspended road dust, industrial materials, brake linings, tire residues, catalytic converter tracers, sea salt spray, etc. Trace metals in CPM showed distinct seasonal and temporal variations depending on the particle source from which they originate. In order to identify the sources of trace metal content of CPM a principal components analysis (PCA) was performed. Five principal components of inter-correlated trace metal species were identified (crustal metals, abrasive vehicular emissions, abrasive mechanical planarization, catalyst converter material, and sea salt), explaining 78.3% of total variance of CPM metal content. Mineral material, closely correlated with some of the rare earth elements, were identified as the main contributor to overall CPM mass, which accounts for 33.2% total CPM metal content, followed by abrasive vehicular tracers and noble metals from catalytic converters. The concentration of the abrasive vehicular tracers was correlated closely across over 2 orders of magnitude, which is seen as evidence that major portions of transition metals (Cu, Ba, Fe, Sb) are released through abrasive vehicular emissions, particularly the wear of brake linings. To better understand the sources of these metal species, their temporal and spatial variations (in each identified class), were investigated with regards to the proximity of each site to major CPM sources. This yields a comprehensive data set for Los Angeles metropolitan airborne trace metals and their sources.

Future Activities:

The major objectives for the next reporting period of the LAB Coarse PM project are:

  • Continue chemical analysis of the collected samples,
  • Continue biological analysis of the collected samples,
  • Continue data analysis,
  • Prepare and present preliminary results at technical conferences, and
  • Begin and complete the upcoming technical manuscripts to be submitted for peer-reviewed publication.

Results from chemical and biological analysis of CPM samples are expected to be completed during the 4th year of the study. Data analysis and the preparation of conference presentations and technical manuscripts will continue through all 4 quarters of Year 4.


Journal Articles on this Report : 3 Displayed | Download in RIS Format

Other project views: All 21 publications 12 publications in selected types All 12 journal articles
Type Citation Project Document Sources
Journal Article Cheung K, Daher N, Kam W, Shafer MM, Ning Z, Schauer JJ, Sioutas C. Spatial and temporal variation of chemical composition and mass closure of ambient coarse particulate matter (PM10-2.5) in the Los Angeles area. Atmospheric Environment 2011;45(16):2651-2662. R833743 (2010)
R833743 (2011)
R833743 (Final)
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  • Abstract: ScienceDirect-Abstract
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  • Other: ScienceDirect-Full Text PDF
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  • Journal Article Moore KF, Verma V, Minguillon MC, Sioutas C. Inter-and Intra-community variability in continuous coarse particulate matter (PM10-2.5) concentrations in the Los Angeles area. Aerosol Science and Technology 2010;44(7):526-540. R833743 (2009)
    R833743 (2010)
    R833743 (2011)
    R833743 (Final)
    R831697 (Final)
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  • Abstract: Taylor&Francis-Abstract
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  • Journal Article Pakbin P, Hudda N, Cheung KL, Moore KF, Sioutas C. Spatial and temporal variability of coarse (PM10-2.5) particulate matter concentrations in the Los Angeles area. Aerosol Science and Technology 2010;44(7):514-525. R833743 (2009)
    R833743 (2010)
    R833743 (2011)
    R833743 (Final)
    R831697 (2013)
    R831697 (Final)
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  • Abstract: Taylor&Francis-Abstract
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  • Other: Taylor&Francis-Full Text PDF
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  • Supplemental Keywords:

    Air pollution, ambient air quality, monitoring, environmental exposure, toxicology, human health, sensitive populations, environmental monitoring, air sampling, airborne particulate matter, chemical characteristics, chemical speciation sampling, source apportionment, quarter (Q);, RFA, Scientific Discipline, Air, particulate matter, Health Risk Assessment, Biology, atmospheric particulate matter, PM10, atmospheric particles, cardiopulmonary responses, human health effects, bioavailability, cardiovascular vulnerability, cardiotoxicity, coarse pm, exposure assessment

    Relevant Websites:

    The USC Aerosol Laboratory web-site describing the on-going activities of Dr. Sioutas’ research group is available at http://www.usc.edu/aerosol/exit EPA

    Progress and Final Reports:

    Original Abstract
  • 2008 Progress Report
  • 2009 Progress Report
  • 2011 Progress Report
  • Final Report