2009 Progress Report: Ultrafine Particles on and Near Freeways

EPA Grant Number: R832413C005
Subproject: this is subproject number 005 , 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: Ultrafine Particles on and Near Freeways
Investigators: Hinds, William C. , Cho, Arthur K. , Froines, John R. , Kleinman, Michael T.
Current Investigators: Hinds, William C. , Cho, Arthur K. , Froines, John R. , Kleinman, Michael T. , Zhu, Yifang
Institution: University of California - Los Angeles , University of California - Irvine
Current Institution: University of California - Los Angeles
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: August 1, 2008 through July 31,2009
RFA: Particulate Matter Research Centers (2004) RFA Text |  Recipients Lists
Research Category: Health Effects , Air


The primary objective is to determine the relative contributions of gaseous and particle components of ambient air samples to oxidative stress related health effects.  A secondary objective is to obtain samples to assess the effect of age and freeze-thaw cycles on redox activity of the samples as measured by the DTT assay.

Progress Summary:

Project 5 consists of three subprojects that either directly or indirectly seek to improve our ability to assess health risk of air pollution by chemical and biological assays used by SCPC.  In the main project, subproject 1, we will obtain a large simultaneous sample of both particulate and gas phase contaminants from the same volume of air. Both phases will be used for the full slate of bioassays and detailed chemical analysis. Samples will be taken at three different locations having a different mix of fresh, aged, and photochemically produced contaminants: a freeway adjacent site, an urban site, and a receptor site.  Subproject 2 will provide concentrator capability for UCLA Particle Center investigators and their projects.  Subproject 3 will obtain large samples at or near UCLA that will be analyzed by our DTT redox activity assay immediately after collection and after a series of aging and freeze-thaw cycles. The objective is to determine the effect of age and freeze-thaw cycles on redox activity of the samples as measured by the DTT assay.
Discussion of Progress
Simultaneous sampling of particles and vapors for assays
At each location we collect particles on Teflon coated glass fiber filters and gas phase contaminants onto XAD resin at 226 Lpm through a PM-2.5 inlet to collect a total sample volume of approximately 400 – 600 m3.  This is repeated up to two more times.  Filters and XAD resin were stored on-site in a refrigerator and periodically transferred to UC-Irvine for freezer storage and then transferred to UCLA for analysis.  Results for gas phase and particle phase samples that have been analyzed or assayed are reported in Project 3.  Composite sample volumes were 399, 423, and 415 m3 for the three replicate samples for the first campaign and 232, 245, and 339 m3 for the second campaign.  The first set of samples was taken at the animal exposure trailer at the UC-Riverside agricultural facility in Riverside, CA.  Riverside is a receptor site with a significant photochemical component.  At each site we conduct two major multi-day sampling campaigns, one in April-May and one in October-November.  Samples were taken for 5.5 hours/day for 6 days and this was repeated three times.  A portion of the XAD resin was sent to Professor Kumagai in Japan for analysis by his assay. The second set of samples also were done in triplicate, but the samples were taken at an urban site with freeway influence, next to USC and near the 110 freeway.  Samples were taken continuously for 48 hours.  The third site is adjacent to and downwind of the I-405 freeway.  Sampling was conducted during 12 daylight hours for 3 consecutive days.  Winter samples at USC and summer samples at the I-405 freeway remain to be collected.  
An outgrowth of the activity on this subproject led to a collaborative effort between Mike Kleinman, Bill Hinds, and Art Cho for a more comprehensive sampling scheme. We prepared and submitted a proposal to the AQMD Asthma Consortium for funding to conduct simultaneous sampling for:  (1) animal exposure (direct with a concentrator); (2) the full battery of chemical and biological assays (samples taken with the concentrator plus impinger); (3) detailed physical characterization including number concentration, size distribution, PM-2.5 mass concentration, elemental carbon, and particle bound PAHs; and (4) filter and XAD resin samples for detailed chemical analysis of the gas phase and particle phase. This will provide a direct comparison of in-vivo response, chemical and bioassay response for gas and particle phases, and detailed physical and chemical analysis from simultaneous, collocated samplers. The project recently has been approved and funded and we are planning the sampling and exposure campaign. 
Concentrator testing, modification, and deployment
As described in previous progress reports, we made many modifications to our concentrator to make it more portable, easier to use, more reliable, and capable of producing a more stable output.  In all cases we found some particle size dependence for the enrichment factor with the greatest enrichment factors in the 20-25 nm particle size range.  Best results were obtained using only one channel at a time. 
Redox Decay Study
This subproject seeks to systematically determine the extent to which redox activity of a sample of CAPs diminishes as a result of storage and/or freeze/thaw cycling.  Our observations suggest this may be happening and other investigators have observed such changes.  Large filter or impinger samples will be collected at or near UCLA.  At the conclusion of each sampling period a portion will be immediately assayed by the DTT assay and the remainder split with a portion stored in a refrigerator and the rest stored in a freezer (-4 °C).  Over the next 6 weeks, DTT assays will be performed on samples with various storage and freeze/thaw histories.  All tests will be conducted in triplicate.  Once a consistent decay can be demonstrated, we will define and test conditions or treatments that minimize loss of DTT activity.
CARB study: Cardiovascular Health Effects of Fine and Ultrafine Particles during Freeway Travel
In a related project, funded by the California Air Resources Board (CARB), we have developed an instrumented van for human exposure to freeway air while traveling on a freeway. EPA and SCPC contributed to this project through partial salary support for Dr. Yifang Zhu. The study seeks to evaluate short-term measures of exposure and response by measuring heart rate variability, and 26 cytokines and other blood factors before, after, and 20 hours after a 2-hour exposure to freeway or filtered air. The van includes a HEPA air filtration system, a two-person exposure chamber, a vibration isolation table, nine near real-time instruments, and a battery power supply.  Instruments include a CPC, SMPS, aethelometer, particle-bound PAH, PM-10, PM-2.5, NOx, CO<em>2</em>, CO, temperature, relative humidity, and GPS. The van has and will benefit the SCPC for the projects described in this report.  We have completed all exposure runs for all 19 subjects. 
Average total particle number concentration measured by a condensation particle counter (CPC) of unfiltered air observed inside the enclosure was 77,800 and 107,500 particles/cm3 on the I-405 and the I-710 freeway, respectively.  The highest 1-minute averaged particle number concentration was 730,000 particles/cm3 on the I-710 freeway.  Bimodal size distributions were typical for both freeways with the first mode around 12–20 nm and the second mode around 50–100 nm.  BC and particle-bound PAH concentrations were more than two times greater on the I-710 than on the I-405 freeway.  Ultrafine particles represented about 36% to 76% of total particle number concentrations on I-405, and 56% to 84% on I-710.  A peak in average particle number concentration of 125,000 particles/cm3 was associated with a traffic speed of 40 to 50 mph.  Most health endpoints did not vary significantly by freeway or filter condition.  However, atrial ectopic beat incidence during and after exposure decreased 20% on average with filtered versus unfiltered air (P<0.05). Between-freeway differences were non-significant, but individual responses related more strongly to count (P=0.01) than to mass (P=0.07). N-terminal pro B-type natriuretic peptide (NT pro-BNP) and vascular endothelial growth factor (VEGF) decreased 30% on average in filtered compared to unfiltered air (P<0.05).  Effects appeared to relate to the ultrafine particulate fraction, in that particle count was strongly correlated with arrhythmia incidence, while PM-2.5 and PM-10 mass concentrations were not significantly correlated with arrhythmia incidence. Rigorous double-blind conditions and filtered-air controls in this study rule out other traffic-related stresses or pollutant gases as causes of the particulate matter-associated cardiovascular effects.

Future Activities:

As outlined above, we will continue to take large volume samples for particle and gas phase contaminants at urban and freeway sites.  All current assays will be conducted on the samples and the chemical and physical analyses will be used in interpreting the results.  We will continue working with the concentrator until we are confident we can get reliable and reproducible results with it.  We expect this phase to be completed by summer 2009.  Once we establish an acceptable sampling protocol we will take samples for the redox decay study.

Journal Articles:

No journal articles submitted with this report: View all 34 publications for this subproject

Supplemental Keywords:

Health effects, Human health, sensitive populations, dose-response, enzymes, particulates, epidemiology, environmental chemistry, modeling, RFA, Health, Scientific Discipline, Air, particulate matter, Environmental Chemistry, Health Risk Assessment, Risk Assessments, Ecological Risk Assessment, Ecology and Ecosystems, cardiopulmonary responses, chemical characteristics, human health effects, toxicology, cardiovascular vulnerability, airborne particulate matter, chemical composition, biological mechanisms, biological mechanism , traffic related particulate matter, human exposure, mobile sources, ambient particle health effects, ultrafine particulate matter, respiratory impact, PM, cardiotoxicity, cardiovascular disease, human health risk

Progress and Final Reports:

Original Abstract
  • 2006 Progress Report
  • 2007 Progress Report
  • 2008 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