2003 Progress Report: Physical and Chemical Characteristics of PM in the LAB (Source Receptor Study)

EPA Grant Number: R827352C014
Subproject: this is subproject number 014 , established and managed by the Center Director under grant R827352
(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: Physical and Chemical Characteristics of PM in the LAB (Source Receptor Study)
Investigators: Sioutas, Constantinos , Cho, Arthur K. , Froines, John R. , Harkema, Jack , Hinds, William C. , Kleinman, Michael T. , Miguel, Antonio
Current Investigators: Sioutas, Constantinos
Institution: University of Southern California , Michigan State University , University of California - Irvine , University of California - Los Angeles
Current Institution: University of Southern California , University of Southern California
EPA Project Officer: Chung, Serena
Project Period: June 1, 1999 through May 31, 2005 (Extended to May 31, 2006)
Project Period Covered by this Report: June 1, 2002 through May 31, 2003
RFA: Airborne Particulate Matter (PM) Centers (1999) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Particulate Matter , Air


Mobile sources constitute one of the most important particulate matter (PM) sources in large metropolitan areas such as the Los Angeles Basin (LAB). Within this basin (and without a doubt in several metropolitan areas of similar morphology), there are three distinct air pollution (hence exposure) regimes that can be identified with respect to mobile sources: (1) areas that fall within the “zone of influence” of a freeway or a busy thoroughfare; (2) areas that represent a typical “urban background,” but not immediately affected by a freeway; and (3) areas downwind from urban sources, in which the main aerosol source is advection of air parcels originally emitted from the polluted upwind urban areas. It is common to refer to the former air pollution regime as “source” and to the latter as “receptor” sites.

The objective of this research project is to address this theme by conducting toxicological studies, which make use of our coarse, fine, and ultrafine concentrators for animal, in vitro, and human clinical research. These studies emphasize the mechanistic-based hypothesis testing with particular reference to allergic airway and cardiovascular disease from exposure to concentrated air particles and copollutants using our mobile particle concentrators. Central to these studies is the ability to characterize the exposure atmosphere of these toxicological studies. Detailed, state-of-the-art characterizations of the airborne concentrations, size distribution, and other chemical/physical elements of ambient air particulate within the LAB in relation to health studies were conducted.

This is one of the projects conducted by the Southern California Particle Center and Supersite (SCPCS). The progress for the other projects is reported separately (see reports for R827352 and R827352C001 through R827352C020).

Progress Summary:

Seasonal and Spatial Variability of the Size-Resolved Chemical Composition of PM10 in the LAB

For a period of almost 3 years, sampling of size-fractionated ambient PM10 was performed at urban source sites (Downey and the University of Southern California [USC]) and inland receptor sites (Claremont and Riverside) in the LAB as part of the SCPCS. Results for size-resolved PM10 mass, inorganic ions (sulfate and nitrate), metals, elemental carbon, and organic carbon were obtained. Three collocated microorifice uniform deposit impactors (MOUDIs) were deployed to collect 24-hour samples roughly once a week. Ultrafine particle concentrations (dp < 0.1 mm) were found to be the highest at the source sites, resulting from fresh vehicular emissions. Mass concentrations in the accumulation mode (0.1 < dp < 2.5 mm) were lower in winter than in summer, especially at the receptor sites. PM concentrations in the coarse mode (2.5 < dp < 10 mm) were lower in winter and were composed mostly of nitrate and crustal elements (iron, calcium, potassium, silicon, and aluminum). Consistent relative levels of these elements indicate a common source of soil and/or road dust. In the accumulation mode, nitrate and organic carbon were predominant, with higher nitrate levels found at the receptor sites. The ultrafine mode PM consisted of mostly organic carbon, with higher wintertime levels at the source sites because of increased organic vapor condensation from vehicles at lower temperatures. Conversely, higher ultrafine organic carbon levels at the receptor areas are a result of secondary organic aerosol formation by photochemical reactions as well as increased advection of polluted air masses from upwind. This study is described in greater detail by Sardar, et al. (2004).

Diurnal Variations of Individual Organic Compound Constituents of Ultrafine and Accumulation Mode PM in the LAB

Individual organic compounds can be used as tracers for primary sources of ambient PM in chemical mass balance receptor models. Previous work has examined PM2.5 only and usually over long sampling periods encompassing entire days or longer. In this study, a high-flow rate, low pressure-drop ultrafine particle separator was deployed to collect sufficient mass for organic speciation of ultrafine and accumulation mode aerosol on a diurnal basis. Particles between 0.18 and 2.5 mm in diameter were collected on a quartz-fiber impaction substrate, and ultrafine particles below 0.18 mm were collected downstream on a high-volume filter. Four daily time period samples (morning, midday, evening, and overnight) were sampled during 5 weekdays to form a weekly average composite for each diurnal period. Sampling was conducted at two sites over two seasons; summer (August) and winter (January) samples were collected at both an urban site near downtown Los Angeles (USC) and a downwind, inland site in Riverside, California. Hopanes, used as organic markers for vehicular emissions, were found to exist primarily in the ultrafine mode. Levoglucosan, an indicator of wood combustion, was quantified in both size ranges, but more was present in the accumulation mode particles. An indicator of photochemical secondary organic aerosol formation, 1,2 benzenedicarboxylic acid, was found primarily in the accumulation mode and varied with site, season, and time of day as one would expect for a photochemical product. The atmospheric variations of particulate cholesterol and other organic acids were also considered. By examining the diurnal variation, size fractionation, and intercorrelations of individual organic compounds, the sources and atmospheric fate of these tracers can be better understood and their utility as molecular markers can be assessed. This study is described in greater detail by Fine, et al. (2004a).

Size-Fractionated Measurements of Ambient Ultrafine Particle Chemical Composition in Los Angeles Using the NanoMOUDI

Ambient ultrafine particles have gained attention with recent evidence showing them to be more toxic than larger ambient particles. Few studies have investigated the distribution of chemical constituents within the ultrafine range. The current study explores the size-fractionated ultrafine (10-180 nm) chemical composition at urban source sites (USC and Long Beach) and inland receptor sites (Riverside and Upland) in the LAB during three different seasons. Size-fractionated ultrafine particles were collected by a NanoMOUDI during a period of 2 weeks at each site. Measurements of ultrafine mass concentrations varied from 0.86 to 3.5 μg/m3, with the highest concentrations observed in the fall. The chemical composition of ultrafine particles ranged from 32-69 percent for organic carbon, 1-34 percent for elemental carbon, 0-24 percent for sulfate, and 0-4 percent for nitrate. A distinct organic carbon mode was observed between 18 and 56 nm in the summer, possibly indicating photochemical secondary organic aerosol formation. The elemental carbon levels are higher in winter at the source sites because of lower inversion heights and are higher in summer at the receptor sites because of increased long-range transport from upwind source areas. Nitrate and sulfate were measurable only in the larger particle size ranges of ultrafine PM. Collocated continuous measurements of particle size distributions and gaseous pollutants helped to differentiate ultrafine particle sources at each site. This study is described in greater detail by Sardar, et al. (submitted, 2004).

Journal Articles:

No journal articles submitted with this report: View all 66 publications for this subproject

Supplemental Keywords:

particulate matter, PM, quinones, polycyclic aromatic hydrocarbons, PAHs, aldehydes, ketones, metals, allergic airway disease, human exposure studies, asthma, cardiovascular effects, aerosol sampling, atmospheric aerosol, environmental monitoring, environmental statistics, California, CA, Los Angeles, acute exposure, aerosols, air pollution, air quality, air toxics, airway disease, allergen, allergic response, ambient aerosol, assessment of exposure, asthma triggers, atmospheric chemistry, bioaerosols, biological response, childhood respiratory disease, children, dosimetry, environmental hazard exposures, environmental health hazard, environmental triggers, environmentally caused disease, epidemiology, exposure assessment, health effects, home, household, human exposure, human health effects, indoor air quality, inhaled particles, lead, outdoor air, particle concentrator, particle transport, particulate exposure, particulates, sensitive populations, toxicology, toxics,, RFA, Health, Scientific Discipline, PHYSICAL ASPECTS, Air, Geographic Area, HUMAN HEALTH, particulate matter, Environmental Chemistry, Air Pollutants, State, Risk Assessments, Biochemistry, Health Effects, Physical Processes, ambient aerosol, asthma, children's health, aldehydes, epidemiology, quinones, exposure, allergic airway disease, air pollution, children, PAH, air sampling, aerosol composition, California (CA), allergens, aerosols, atmospheric chemistry, dosimetry

Relevant Websites:

http://www.scpcs.ucla.edu/exit EPA

Progress and Final Reports:

Original Abstract
  • 1999
  • 2000
  • 2001 Progress Report
  • 2002 Progress Report
  • 2004
  • Final Report

  • Main Center Abstract and Reports:

    R827352    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).
    R827352C001 The Chemical Toxicology of Particulate Matter
    R827352C002 Pro-inflammatory and the Pro-oxidative Effects of Diesel Exhaust Particulate in Vivo and in Vitro
    R827352C003 Measurement of the “Effective” Surface Area of Ultrafine and Accumulation Mode PM (Pilot Project)
    R827352C004 Effect of Exposure to Freeways with Heavy Diesel Traffic and Gasoline Traffic on Asthma Mouse Model
    R827352C005 Effects of Exposure to Fine and Ultrafine Concentrated Ambient Particles near a Heavily Trafficked Freeway in Geriatric Rats (Pilot Project)
    R827352C006 Relationship Between Ultrafine Particle Size Distribution and Distance From Highways
    R827352C007 Exposure to Vehicular Pollutants and Respiratory Health
    R827352C008 Traffic Density and Human Reproductive Health
    R827352C009 The Role of Quinones, Aldehydes, Polycyclic Aromatic Hydrocarbons, and other Atmospheric Transformation Products on Chronic Health Effects in Children
    R827352C010 Novel Method for Measurement of Acrolein in Aerosols
    R827352C011 Off-Line Sampling of Exhaled Nitric Oxide in Respiratory Health Surveys
    R827352C012 Controlled Human Exposure Studies with Concentrated PM
    R827352C013 Particle Size Distributions of Polycyclic Aromatic Hydrocarbons in the LAB
    R827352C014 Physical and Chemical Characteristics of PM in the LAB (Source Receptor Study)
    R827352C015 Exposure Assessment and Airshed Modeling Applications in Support of SCPC and CHS Projects
    R827352C016 Particle Dosimetry
    R827352C017 Conduct Research and Monitoring That Contributes to a Better Understanding of the Measurement, Sources, Size Distribution, Chemical Composition, Physical State, Spatial and Temporal Variability, and Health Effects of Suspended PM in the Los Angeles Basin (LAB)