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2006 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. , Zhu, Yifang
Current Investigators: Hinds, William C. , Cho, Arthur K. , Froines, John R. , Kleinman, Michael T.
Institution: University of California - Los Angeles , University of Southern California
EPA Project Officer: Katz, Stacey
Project Period: October 1, 2005 through September 30, 2010
Project Period Covered by this Report: October 1, 2005 through September 30, 2006
RFA: Particulate Matter Research Centers (2004)
Research Category: Particulate Matter

Description:

Objective:

To determine the relative contributions of gaseous and particle components of ambient air samples to oxidative stress related health effects.

Progress Summary:

Concentrator Testing and Modification

Our three channel Sioutas aerosol concentrator was tested and a number of modifications were made to make it readily portable and easier to use for our purposes. The refrigeration unit was mounted on a platform truck and the other components on a second platform truck. A drain with a valve was installed at the bottom of the humidifier tank. The large rotary vane pump is now housed in a noise control box on wheels. The second platform truck has a detachable vertical frame section to support the condenser columns, virtual impactors (concentrators), a control panel, and associated tubing. This arrangement allows easy transportation in a van or small truck.

The inlet to the humidifier now floats so that it is easily adjustable and maintains a precisely controlled gap between the airflow exit and the water surface. The control panel houses two pressure gauges, two flow control rotameters, and a differential temperature controller. The latter maintains a constant (within ± 0.2ºC) differential temperature between the incoming air and the exiting humidified air. The control panel also has mounts for an impinger, filter holder, and personal sampling pumps.

On-Freeway Exposures

This project is jointly funded between the SCPC and California Air Resources Board (CARB). We have developed an instrumented van for human exposure of freeway air while traveling on a freeway. The study seeks to evaluate a variety of 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 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, CO2, CO, temperature, relative humidity, and GPS. The van has and will benefit the SCPC in the projects outlined below.

Pilot Study of Inside/Outside Ratios for Vehicles

We conducted pilot studies to develop the technique and obtained preliminary data for Inside/Outside (I/O) of particulates for vehicle while driving on a freeway. Particle number concentrations and size distributions were measured under different operating conditions of vehicle ventilation system (windows open, AC on/off, recirculation on/off). In-vehicle air change rates were 60–120/hr. Maximum in-cabin protection (~85%) was obtained with ventilation conditions of “recirculation on” and high fan speeds. In-cabin and outdoor particle size distributions in the 7–300 nm range were observed to be mostly bimodal, with the smaller-sized peak occurring at 10-30 nm and the larger-sized peak occurring at 60-100 nm. The factory-installed particulate filter in the vehicle ventilation system offered an in-cabin protection of about 50% for particles in the 7-40 nm size range, and 20-30% for particles in the 40-~200 nm size range. The modified van described above contributed to the development of methodology for this project.

Simultaneous Sampling of Particles and Vapors

We conducted preliminary measurements to support the design of a planned high volume sampling system for capturing both the particulate and vapor phase contaminants in a 500 m3 air sample. Three locations will be sampled with replications: on-freeway; urban away from freeways; and receptor site with significant photochemically produced aerosol. The modified van described above will be used for these measurements. Preliminary testing included pressure drop and nanoparticle collection efficiency of Teflon coated glass fiber filters. Different pumps were evaluated for energy efficiency because the system needs to operate for many hours on batteries while traveling on a freeway.

Ultrafine Particle Morphology

We have used the instrumented van to continue our study of changes in ultrafine particles near freeways by taking Transmission Electron Microscopy (TEM) samples for morphological analysis of 50 nm mobility diameter particles. Samples were taken on-freeway and at 30, 60, and 90 m downwind of the freeway. For samples collected on and near I-405, most (>90%) opaque particles were surrounded by a transparent material. This suggests that the aerosol was internally mixed. The number of particles with multiple inclusions increased with distance from the freeway, suggesting that dilution does not prevent particles from colliding and merging.

Future Activities:

We plan to use the concentrator to obtain concentrated samples of fine and ultrafine particles for chemical or biological assays. We plan to conduct a study of I/O ratios for vehicles under different ventilation conditions. We plan to collect large samples of particulate and vapors on freeways and other sites for chemical and biological assays.

Journal Articles:

No journal articles submitted with this report: View all 6 publications for this subproject

Supplemental Keywords:

health effects, human health, sensitive populations, dose-response, enzymes, particulates, epidemiology, environmental chemistry, modeling,
Relevant Websites:

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

Progress and Final Reports:
Original Abstract
2007 Progress Report
2008 Progress 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

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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