2007 Progress Report: Project 3 -- Inhalation Exposure Assessment of San Joaquin Valley Aerosol

EPA Grant Number: R832414C003
Subproject: this is subproject number 003 , established and managed by the Center Director under grant R832414
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: San Joaquin Valley Aerosol Health Effects Research Center (SAHERC)
Center Director: Wexler, Anthony S.
Title: Project 3 -- Inhalation Exposure Assessment of San Joaquin Valley Aerosol
Investigators: Pinkerton, Kent E. , Bonham, Ann , Chen, Chao-Yin , Kleeman, Michael J.
Current Investigators: Pinkerton, Kent E. , Kleeman, Michael J.
Institution: University of California - Davis
EPA Project Officer: Chung, Serena
Project Period: October 1, 2005 through September 30, 2010 (Extended to September 30, 2011)
Project Period Covered by this Report: October 1, 2006 through September 30, 2007
RFA: Particulate Matter Research Centers (2004) RFA Text |  Recipients Lists
Research Category: Health Effects , Air


Epidemiological evidence suggests that the association between cardiac mortality and PM 10 concentrations changes between the summer and winter months in the San Joaquin Valley (SJV). This shift is likely caused by seasonal variation in the size and composition distribution of airborne particles. This project will perform inhalation exposure and particle characterization studies at rural and urban locations in different seasons to quantify the features of the airborne particles that are associated with adverse health effects.

Progress Summary:

Progress by Specific Aim

1. Differences in particle concentration, size distribution, and composition that occur as a function of season and location in the San Joaquin Valley (SJV) result in different health outcomes; these outcomes can be detected during inhalation exposure experiments.

To date we have completed two field measurement and exposure studies in the San Joaquin Valley at an urban site located in Fresno, CA (500 East Shaw Avenue). The first field study was conducted during the late summer season (September 5-16, 2006), and the second study at the identical site during the winter season (February 13-24, 2007). In each study male C57/BL6 mice were exposed to concentrated ambient particles (CAPs) for 6 hours/day, 5 days/week for two weeks. Fine/ultrafine ambient particles were collected and concentrated onsite using a Versatile Aerosol Concentrator Enhancement System (VACES). CAPs samples collected during each exposure were analyzed for chemical composition. The results of these exposure studies are currently being analyzed.

2. The increased toxicity of airborne particles during the winter season in the SJV is associated with increased concentrations of ultrafine carbon particles.

A two-pronged approach is being applied to examine the cardiopulmonary consequences of particle exposure, i.e., using both whole body and in vivo studies. This approach includes studies to: (1) measure heart rate variability (HRV) in mice exposed to CAPs or to filtered ambient air, (2) determine the impact of restraint (a stress stimulus) on HRV, 3) evaluate cellular and inflammatory indicators in the lungs by bronchopulmonary lavage and cytokine measurements, and 4) measure neurological changes in gene expression for pro-inflammatory cytokines.

3. The increased toxicity of airborne particles in the SJV during the winter season is associated with increased concentrations of accumulation mode ammonium/nitrate/sulfate particles.

Analysis of the chemical speciation of ambient particles collected during the time of animal inhalation studies is ongoing. Please see #4 under the section below entitled Summary of Mouse CAPs Studies to Date.

4. The health effects of San Joaquin Valley aerosol can be directly related to the emissions source of the fine and ultrafine particles.

Analysis of the chemical speciation of ambient particles collected during the time of animal inhalation studies is ongoing. Please see #4 under the section below entitled Summary of Mouse CAPs Studies to Date.

Summary of Mouse CAPs Studies to Date

  1. The housing prototype insert for maintaining individual mice in the exposure chamber for CAPs studies has worked extremely well for studies completed in Davis and Fresno. The system houses 8 mice per chamber in individual compartments. Eight housing units have been constructed, 4 for sham exposure and 4 for CAPs exposure. For the initial Davis experiment, as well as for the summer and winter urban Fresno studies, the same number of mice (32) were randomly assigned both to sham exposure and to CAPs exposure in each of these three studies. The mice were acclimated to the exposure chamber one week prior to the exposure and randomly rotated through the sub-compartment of the chamber to avoid any potential positional effects and to reduce the stress associated with changes in environment. Up to 18 mice from each group were implanted with an ECG telemetry system at least 2 weeks prior to the exposure protocol. Mice were subjected to CAPs exposure (6 hours/day, 5 days/week, for 2 weeks) for a total of 10 days. A similar set of animals served as sham controls.

    For HRV studies we adapted a stress test (restraint test) to replace exercise stress tests. The restraint test has been shown to alter autonomic regulation of the HRV. Each mouse was placed in an individual restrainer in their home case for two hours. The ECG signals were continuously recorded 4 hours before, during, and 6 hours after the test. In addition, for selected studies we collected blood plasma samples for measurement of circulating cytokines and harvested brain and heart tissues for protein analysis.

  2. To examine CAPs exposure for both the fall and winter seasons, the VACES system was operated 6 hours per day to expose mice to concentrated ambient particles by whole body exposure. During the exposure, a portion of the air was sampled to allow for determination of particle mass, particle number and chemical speciation. After sample analysis was complete, the self-consistency of each sample set will be established through internal checks. The acceptance criteria for HRV data are closely followed through the software, which recognizes spurious, artifactual R-waves of the ECG. All raw signals are checked by eye and all data points checked with Lorenz’s plot to ensure that no artifacts are included in the data analysis. Acceptance criteria for the electrophysiological data will be the reproducibility and quality of the responses according to standard criteria, including an overshoot of all action potentials, a resting membrane potential of at least – 50 mV, a reproducible EPSC peak and decay time and input resistance at the beginning and end of the protocol.

  3. The epidemiological associations between ambient PM2.5 and reduced HRV, in particular, are persuasive and the few animal studies undertaken have underscored the importance of establishing animal models for mechanistic studies. Yet, there remain important gaps: (a) Is there an animal model that when exposed to real world pollutants mimics the cardiovascular and/or pulmonary consequences observed in humans? (b) Are there seasonal (compositional) differences in PM2.5 that contribute to the cardiovascular consequences? (c) Can the mouse be used as a model to study increased susceptibility of cardiopulmonary-compromised individuals and be related to reduced HRV and increased incidence of arrhythmias and/or increased oxidant-related stress associated with exposure to air pollutants?

    We have collected both the environmental and biological data in a mouse model in our state-of-the-art inhalation facilities that deliver environmentally relevant particulate pollutants in the form of CAPs. These data are currently being analyzed. The results of the study will help to answer the above gaps in our understanding of the associations between ambient PM2.5 and reduced HRV. In addition, we hope to provide data on seasonal (compositional) differences in fine/ultrafine particulates that would supply credible science to help inform air quality planning and regulation.

Summary of Particle Size and Composition Fall Exposure Experiment in Fresno
Samples of airborne particulate matter were collected during September 4-9 and September 12-16, 2006 (late summer season) and again on February 13-17 and February 20-24, 2007 (winter season) using six Micro Orifice Uniform Deposit Cascade Impactors (MOUDIs) and three Reference Ambient Air Sampler (RAAS). Samples were collected for 6hrs each day during the animal exposure periods. Three of the MOUDIs were loaded with Teflon collection substrates (used for gravimetric, water soluble ions, and trace metals analysis) while the other three MOUDIs were loaded with Aluminum Foil substrates (used for gravimetric and carbon analysis). Upstream of each MOUDI a PM1.8 cyclone was used to remove coarse particles that might otherwise bounce off collection substrates. Six size fractions below 1.8 μm aerodynamic particle diameter were resolved with the MOUDI operated in this configuration. The RAAS sampler was equipped with multiple channels that employed Teflon filters and Quartz filters to characterize PM1.8 mass.

The PM1.8 mass collected during the Fresno summer event was 15.8 μg m-3 during September 4-9, 2006 and 18.8 μg m-3 during September 12-16, 2007. The PM1.8 mass collected during the Fresno winter event was 23.7 μg m-3 during February 13-17, 2007 and 11.0 μg m-3 during February 20-24, 2007. These concentrations are significantly lower than concentrations experienced during typical air pollution events in the SJV, when PM1.8 concentrations can increase to values greater than 100 μg m-3. Ultrafine (PM0.1) mass concentrations were measured to be 0.3-0.4 μg m-3 during all Fresno summer sampling events (summer and winter). PM0.1 concentrations greater than 2.0 μg m-3 have been measured during previous winter pollution events in the San Joaquin Valley. The low concentrations during the current study period are attributed to the weather conditions (atmosphere was well mixed during all days; rain was recorded at times).

The particle concentrator system can compensate for low ambient concentrations by increasing the exposure concentration by a factor of approximately 13. This will yield representative results during exposure experiments if the composition of the ambient particles is similar to the composition of particles during a true stagnation event. This assumes that the size and composition distribution of particles during the clean and polluted events are similar, but the absolute concentrations are lower during the clean event. The source apportionment of ultrafine particles during these periods of low concentrations will be very challenging and may not be possible if insufficient mass is available for analysis.

Figure 1 illustrates the size and composition distribution of particles collected during at Fresno during Week 1 (Sept 4-9, 2006) and Week 2 (Sept 12-16, 2006). Organic carbon, elemental carbon, and water soluble ions (sulfate, nitrate, etc) make up the majority of the particle size distribution. The Fresno sampling site was located in relatively close proximity to busy surface streets and highways in Fresno. It is expected that the majority of these particles are derived from tailpipe exhaust emissions and / or road dust sources. Elemental analysis of these samples using ICPMS has been completed and the data is being reviewed for QA/QC.

Figure 1: Size and composition distribution of airborne particulate matter measured during Sept 4-9, 2006 (week 1) and Sept 12-16, 2006 (week 2).

Figure 1: Size and composition distribution of airborne particulate matter measured during Sept 4-9, 2006 (week 1) and Sept 12-16, 2006 (week 2).

Figure 1: Size and composition distribution of airborne particulate matter measured during Sept 4-9, 2006 (week 1) and Sept 12-16, 2006 (week 2).

Future Activities:

For the next reporting period, our plan is to (1) continue exposures in the summer season (i.e., August 2007), (2) conduct CAPs experiments in our designated rural site of the San Joaquin Valley (Westside, CA), (3) develop pulmonary and cardiovascular measures of PM effects for week 1 and week 2 of rural summer exposure as well as for the combined 2 weeks of exposure and 4) complete the analysis of respiratory, HRV and stress test impacts for murine studies completed in Fresno during the late summer (September 2006) and winter (February 2007) seasons as well as particle concentration and composition.

Journal Articles on this Report : 1 Displayed | Download in RIS Format

Other subproject views: All 28 publications 21 publications in selected types All 17 journal articles
Other center views: All 128 publications 71 publications in selected types All 64 journal articles
Type Citation Sub Project Document Sources
Journal Article Smith KR, Veranth JM, Kodavanti UP, Aust AE, Pinkerton KE. Acute pulmonary and systemic effects of inhaled coal fly ash in rats: comparison to ambient environmental particles. Toxicological Sciences 2006;93(2):390-399. R832414 (Final)
R832414C003 (2006)
R832414C003 (2007)
R832414C003 (2008)
R832414C003 (Final)
R829215 (Final)
  • Abstract from PubMed
  • Full-text: OUP-Full Text HTML
  • Abstract: Oxford-Abstract
  • Other: OUP-Full Text PDF
  • Supplemental Keywords:

    RFA, Health, Scientific Discipline, PHYSICAL ASPECTS, Air, particulate matter, Environmental Chemistry, Health Risk Assessment, Risk Assessments, Physical Processes, ambient aerosol, lung injury, long term exposure, lung disease, acute cardiovascular effects, airway disease, exposure, airborne particulate matter, San Joaquin Valley, cardiac arrest, human exposure, inhalation, ambient particle health effects, PM, concentrated air particles, cardiovascular disease, human health risk

    Progress and Final Reports:

    Original Abstract
  • 2006 Progress Report
  • 2008 Progress Report
  • 2009 Progress Report
  • 2010 Progress Report
  • Final Report

  • Main Center Abstract and Reports:

    R832414    San Joaquin Valley Aerosol Health Effects Research Center (SAHERC)

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R832414C001 Project 1 -- Pulmonary Metabolic Response
    R832414C002 Endothelial Cell Responses to PM—In Vitro and In Vivo
    R832414C003 Project 3 -- Inhalation Exposure Assessment of San Joaquin Valley Aerosol
    R832414C004 Project 4 -- Transport and Fate Particles
    R832414C005 Project 5 -- Architecture Development and Particle Deposition