2003 Progress Report: Exposure Core

EPA Grant Number: R827355C008
Subproject: this is subproject number 008 , established and managed by the Center Director under grant R827355
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Airborne PM - Northwest Research Center for Particulate Air Pollution and Health
Center Director: Koenig, Jane Q.
Title: Exposure Core
Investigators: Larson, Timothy V. , Claiborn, Candis , Covert, David S. , Kalman, Dave , Lewtas, Joellen , Liu, Sally
Current Investigators: Larson, Timothy V. , Liu, Sally
Institution: University of Washington
EPA Project Officer: Chung, Serena
Project Period: June 1, 1999 through May 31, 2004 (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


The objective of this research project is to provide state-of-the-art particulate matter (PM) sampling and analysis techniques for quantifying exposures and doses and to facilitate cooperation between health, toxicological, and exposure studies. Services of the Exposure Core have been provided across all projects in the Northwest Research Center for Particulate Air Pollution and in the community, including: (1) consulting on exposure aspects of study designs; (2) equipment support and technician training; (3) chemical and physical analyses of exposure samples; (4) study coordination with other PM exposure researchers; and (5) consulting on quality assurance procedures associated with sampling and analysis of exposure metrics. We also have worked with other PM Centers and the U.S. Environmental Protection Agency (EPA) on method comparisons, round-robin sample analysis, and source apportionment issues.

Progress Summary:

Farmer Exposure Study

The Farmer Exposure Study was sponsored by the Northwest Agricultural Center. The objective of this project is to characterize wheat growers’ exposure to agricultural-burning smoke emissions during their field-burning operations. The Exposure Core helped to develop and refine the field-sampling protocols for measuring exposure using portable battery-operated or passive samplers. We used these protocols during fieldwork conducted in Columbia County, where Tim Gould helped coordinate recruitment of study subjects with the assistance of the County Conservation District and Agricultural Extension Service.

The measured exposures were extremely high because of the proximity of subjects to the combustion of wheat stubble residue and the resuspension of soot caused by their field vehicles. For short exposures of only a few hours, the variability as measured by real-time fine PM monitors was quite large. Correlation of real-time monitor results with the integrated filter samples was problematic.

Diesel Exposure Pilot Study

The objective of the Diesel Exposure Pilot Study is to test the methods and procedures for studying the health effects of controlled exposures to selected levels of diesel exhaust. During the 2003-2004 operating year, we continued to troubleshoot and refine the operation of the diesel emission dilution system. Distinct changes in the properties of the diesel engine exhaust resulted in a systematic examination of all components of the exhaust sampling and dilution system. We redesigned the exhaust transfer system and added capacity to the sampling system to achieve the diluted fine PM mass concentrations specified in the pilot study design.

Documentation of operations and maintenance for the diesel emission dilution system has been an ongoing activity throughout the current year. Use of the facility for the human subject pilot study began in January 2004 on a steady basis and will continue through the end of June. We are finding a good correlation between mass measurements and surrogate measures of light scattering by nephelometry, although real-time mass measurements by the tapered element oscillating microbalance device (TEOM) are biased high relative to integrated filter measurements using Harvard impactors.

Seattle Air Toxic Project

We assisted the Western Washington Department of Ecology with the analysis of their Air Toxic Pilot Study. In this project, the analysis of variance results indicated significant spatial variation for all air toxics except for acetaldehyde, butadiene, carbon tetrachloride, and manganese. The Generalized Linear Model results showed that the seasonal variation was, on average, 26 percent larger than the spatial variation. The principal component analysis identified two components that accounted for 57 percent of the total variance. The first principal component represented the average air toxics levels and the second principal component represented the mixing features of the potential sources. The scatter plot of the principal component scores and the eigenvectors revealed that one of the monitoring sites ( Lake Forest Park) showed significantly high levels of arsenic in the fall, probably impacted by woodsmoke. The risk assessment results showed that the sum of cancer risks from the 18 monitored air toxics was above 1 x 10-6, whereas the sum of the hazard index was below 1. Formaldehyde, benzene, and carbon tetrachloride are the top contributors to the sum of cancer risks.

IP Analysis

Another goal is to analyze all Teflon filters collected in the Seattle Panel Study for light-absorbing carbon using the integrated plate. We have analyzed filters through session “M5” (YeaR2 of the project) for indoor and outdoor samples. All personal samples have been analyzed. Fatally flagged filters were not analyzed. Only indoor, outdoor, and central site filters have yet to be analyzed. Since the start of the yeaR2003 (and through April 2004), about 1,000 samples have been analyzed. We also have analyzed Year 4 samples in support of the exhaled nitric oxide study done on that panel of adult asthmatics and chronic obstructive pulmonary disease patients. Those results were recently presented as a poster at the American Thoracic Society 100th International Conference in Orlando, Florida (Jansen, et al., 2004).


During 2003, David Hardie helped the PM Center “cores” prepare Quality Assurance Project Plans (QAPPs) and we performed mock audits on them. The audits were intended to simulate an EPA technical systems audit.

Alpine Exposure Assessment Study

We collaborated with Dr. Ralph Delfino at the University of California at Irvine in his Alpine Asthma Air Pollution Study. In the Alpine study, we first developed a series of quality control (QC) procedures to improve the data quality of the personal nephelometers (pDR). We identified as outliers 0.01 percent and 0.03 percent of 1-minute and 15-minute pDR measurements, respectively. Baseline drifts were evidenced in 14.8 percent of daily time series. Both were removed from analysis. The relative humidity (RH) effect on the light-scattering response of the pDRs was removed by an RH correction equation. After the QC procedures, the average R2 between filter samples and the pDRs at fixed sites was 0.60.

We then conducted exposure assessment and found that the subjects received 29.2 percent of their exposures at school, although they only spent 16.4 percent of their time there. In addition, the personal cloud increased with increasing activity levels and was higher outdoors than indoors. We also built models to predict personal PM exposures based on either microenvironmental data or central site PM2.5 measurements and evaluated the modeled exposures against the actual personal measurements. The multiple regression model with central site PM concentration as the main predictor had a better prediction power ( R2 = 0.41) than a three-microenvironmental model ( R2 = 0.11). From the time-location-activity information and the particle infiltration efficiencies (mean = 0.70) calculated from a recursive mass-balance model, it was estimated that the percent of daily personal exposures resulting from ambient, indoor-generated, and personal activity PM2.5 were 41.2 percent, 22.9 percent, and 35.9 percent, respectively, when the modeling error was minimized.

PM Center Round-Robin In Vitro Study

We participated in a multi-Center collaboration with researchers from New York University (NYU), the University of Rochester, Brigham Young University, and EPA. Specifically, we coordinated the field sampling in the Seattle area using the ChemVol ® high-volume sampler. Weekly samples of coarse, fine, and ultrafine particles were collected at the Lynnwood monitoring site. This site is operated by the Puget Sound Clean Air Agency (PSCAA), who generously gave us permission to operate this large sampling device and provided electrical power. Four weekly samples were collected, and the sample media have been sent to NYU for extraction and eventual distribution to PM Center collaborators. The PSCAA also collected continuous TEOM and nephelometer data as well as PM2.5 filter samples every third day during the sample period. We also provided a 1 week’s ChemVol ® sample to Dan Luchtel for his toxicological assays.


Diesel Exposure Facility Development

The Exposure Core also provided technical assistance and guidance regarding characterization and operation of the diesel exposure facility. Specifically, we helped to oversee the development of measurement systems for both gases and particles, as well as control systems required to maintain constant concentration levels in the exposure room. We also will continue to provide technical advice on detailed chemical characterization of the aerosol, including setup and operation of the versatile air pollution sampler and particle acidity measurements.

Source Apportionment

We will continue to collaborate on source apportionment issues with particular emphasis on the Beacon Hill site. This is the central site for our major panel studies, and we are examining not only issues of spatial variation in source contribution estimates (i.e., “How representative is Beacon Hill?”), but also issues of source-related exposure pathways. Several publications on these issues are listed below.


We provided technical support and necessary training for the diesel school bus study. Although we have not taken a direct role in data analysis for the Agricultural Burning Smoke Exposure Study, we have continued to support other researchers and help them with interpretation of results based on our familiarity with the study design and field implementation. We also have coordinated the sharing of fine particle Teflon filter samples between the local air agency and our toxicology investigators and provided guidance on which samples to choose for these studies.

Future Activities:

We will continue to provide analytical and monitoring technologies to continuing studies in Year 6 of the project. Manuscripts on the following topics are being prepared: (1) the results of wildfire health effects study conducted in summer 2001; and (2) a characterization of the Diesel Exhaust Dilution and Exposure Facility to use as a reference for subsequent papers reporting health effects from diesel exposures at the facility.

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

Other subproject views: All 21 publications 21 publications in selected types All 21 journal articles
Other center views: All 209 publications 113 publications in selected types All 109 journal articles
Type Citation Sub Project Document Sources
Journal Article Kim E, Hopke PK, Larson TV, Maykut NN, Lewtas J. Factor analysis of Seattle fine particles. Aerosol Science and Technology 2004;38(7):724-738. R827355 (2004)
R827355 (Final)
R827355C004 (2003)
R827355C008 (2003)
R827355C008 (Final)
R827354 (Final)
R827354C001 (Final)
R832415 (2010)
R832415 (2011)
R832415 (Final)
  • Full-text: Taylor&Francis-Full Text HTML
  • Abstract: Taylor&Francis-Abstract
  • Other: Tayor&Francis-Full Text PDF
  • Journal Article Kim E, Hopke PK, Larson TV, Covert DS. Analysis of ambient particle size distributions using Unmix and positive matrix factorization. Environmental Science & Technology 2004;38(1):202-209. R827355 (2004)
    R827355 (Final)
    R827355C004 (2003)
    R827355C008 (2002)
    R827355C008 (2003)
    R827355C008 (Final)
    R827354 (Final)
    R827354C001 (Final)
    R827354C002 (2004)
    R832415 (2010)
    R832415 (2011)
    R832415 (Final)
  • Abstract from PubMed
  • Full-text: ACS-Full Text HTML
  • Abstract: ACS-Abstract
  • Other: ACS-Full Text PDF
  • Journal Article Larson T, Gould T, Simpson C, Liu L-JS, Claiborn C, Lewtas J. Source apportionment of indoor, outdoor, and personal PM2.5 in Seattle, Washington, using positive matrix factorization. Journal of the Air & Waste Management Association 2004;54(9):1175-1187. R827355 (2004)
    R827355 (Final)
    R827355C003 (Final)
    R827355C008 (2003)
    R827355C008 (Final)
    R827355C010 (Final)
  • Abstract from PubMed
  • Full-text: Taylor&Francis-Full Text PDF
  • Abstract: Taylor&Francis-Abstract
  • Supplemental Keywords:

    ambient particles, fine particles, combustion, health, exposure, biostatistics, susceptibility, human susceptibility, sensitive populations, air toxics, genetic susceptibility, indoor air, indoor air quality, indoor environment, tropospheric ozone, California, CA, polyaromatic hydrocarbons, PAHs, hydrocarbons, acute cardiovascular effects, aerosols, air pollutants, air pollution, air quality, airborne pollutants, airway disease, airway inflammation, allergen, ambient aerosol, ambient aerosol particles, ambient air, ambient air quality, ambient particle health effects, animal model, assessment of exposure, asthma, atmospheric aerosols, atmospheric chemistry, biological markers, biological response, cardiopulmonary response, cardiovascular disease, children, children’s vulnerability, combustion, combustion contaminants, combustion emissions, epidemiology, exposure, exposure and effects, exposure assessment, harmful environmental agents, hazardous air pollutants, health effects, health risks, human exposure, human health effects, human health risk, incineration, inhalation, lead, morbidity, mortality, mortality studies, particle exposure, particle transport, particulates, particulate matter, risk assessment,, RFA, Health, Scientific Discipline, PHYSICAL ASPECTS, Air, ENVIRONMENTAL MANAGEMENT, Geographic Area, particulate matter, Toxicology, air toxics, Environmental Chemistry, Health Risk Assessment, Air Pollutants, Epidemiology, State, Air Pollution Effects, Northwest, Risk Assessments, Susceptibility/Sensitive Population/Genetic Susceptibility, Biochemistry, Physical Processes, genetic susceptability, Atmospheric Sciences, Risk Assessment, ambient aerosol, ambient air quality, biostatistics, health effects, particulates, sensitive populations, cardiopulmonary responses, health risks, human health effects, morbidity, exposure and effects, acute cardiovascular effects, dose-response, exposure, hazardous air pollutants, epidemelogy, air pollution, Human Health Risk Assessment, particle exposure, cardiopulmonary response, human exposure, inhalation, atmospheric aerosols, ambient particle health effects, mortality studies, PM, human susceptibility, mortality, California (CA), aerosols, air quality, atmospheric chemistry, cardiovascular disease, exposure assessment, human health risk, particle transport, toxics

    Relevant Websites:

    http://depts.washington.edu/pmcenter/ Exit

    Progress and Final Reports:

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

  • Main Center Abstract and Reports:

    R827355    Airborne PM - Northwest Research Center for Particulate Air Pollution and Health

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R827355C001 Epidemiologic Study of Particulate Matter and Cardiopulmonary Mortality
    R827355C002 Health Effects
    R827355C003 Personal PM Exposure Assessment
    R827355C004 Characterization of Fine Particulate Matter
    R827355C005 Mechanisms of Toxicity of Particulate Matter Using Transgenic Mouse Strains
    R827355C006 Toxicology Project -- Controlled Exposure Facility
    R827355C007 Health Effects Research Core
    R827355C008 Exposure Core
    R827355C009 Statistics and Data Core
    R827355C010 Biomarker Core
    R827355C011 Oxidation Stress Makers