2002 Progress Report: Personal PM Exposure Assessment

EPA Grant Number: R827355C003
Subproject: this is subproject number 003 , 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: Personal PM Exposure Assessment
Investigators: Liu, Sally , Claiborn, Candis , Kalman, Dave , Larson, Timothy V.
Current Investigators: Liu, Sally , Allen, Ryan , Claiborn, Candis , Kalman, Dave , Koenig, Jane Q. , Larson, Timothy V. , Simpson, Chris
Institution: University of Washington , Washington State University
Current 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
Project Amount: Refer to main center abstract for funding details.
RFA: Airborne Particulate Matter (PM) Centers (1999) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Particulate Matter , Air


The objectives of this research project are to: (1) characterize and compare personal, indoor, and outdoor exposures to the various components of particulate matter (PM) PM10 and PM2.5 among three major susceptible subpopulations and one control healthy cohort; (2) determine the strength of the relationship of the particle exposures of the high-risk subpopulations to the concentrations measured by a central monitoring station; (3) characterize the key factors influencing this relationship and develop models for predicting personal PM exposures; (4) provide exposure models for the concurrent epidemiologic study to reach unbiased estimation of health effects; and (5) update the study design and analysis goals based on the new findings and new hypotheses.

Progress Summary:

We have published the overarching exposure assessment paper that describes Years 1 and 2 of the project's panel study. The paper characterizes PM exposures and constructs exposure models for the four studied susceptible populations (Liu, et al., 2003). We found that personal exposures varied by subpopulation, with the longitudinal relationship between personal-and central-site PM2.5 measurements depending on the personal attenuation factor and the contribution from ambient PM sources. PM2.5 exposures among the chronic obstructive pulmonary disease (COPD) and cardiac subjects can be predicted with relatively good power with a microenvironmental model composed of three microenvironments.

We have been working on source apportionment analysis for outdoor, indoor, and personal PM measurements. Major sources contributing to PM exposures in these microenvironments have been identified using a combination of positive matrix factorization method and chemical mass balance models.

We worked on separating indoor PM2.5 concentrations into indoor- and outdoor-generated components (Allen, et al., 2002). The separation of indoor air into these components is a necessary step to obtain the estimation of personal exposure to indoor- and outdoor-generated particles. These classes of particles have different temporal variability, sources, chemical characteristics, and may have different toxicities. Characterizing personal exposure to outdoor-generated particles is necessary to understand the epidemiological associations between ambient concentrations and health effects. Our accomplishments are listed below.

Estimating Contribution of Indoor- and Outdoor-Generated Particles to Indoor PM

· A newly adapted recursive mass-balance model was used in combination with light-scattering data collected at 55 residences in Seattle to estimate particle penetration (P, 0.94 ± 0.10), air exchange rate (a, 0.54 ± 0.60 hr-1), particle decay rate (k, 0.20 ± 0.16 hr-1), and particle infiltration (Finf, 0.65 ± 0.21).

· We compared the Finf estimates with the sulfur tracer method. The two methods were consistent with each other (N = 14; regression slope = 1.03; R2 = 0.78).

· Outdoor-generated particles accounted for an estimated average of 79 ± 17 percent of the indoor PM concentration, with a range of 40 to 100 percent at individual residences.

· Seasonal differences were noted for P, a, and k. The average P, a, and k for residences monitored during the heating season (October to February) were 0.89 ± 0.11, 0.37 ± 0.17, and 0.27 ± 0.18, respectively. During the nonheating season (March to September), the average values of P, a, and k were 0.99 ± 0.03, 0.72 ± 0.82, and 0.12 ± 0.08, respectively. The seasonal differences for all three parameters were significant (p < 0.05).

· Seasonal differences for Finf also were noted. Residences monitored during the nonheating season had a mean Finf of 0.79 ± 0.18, and residences monitored during the heating season had a mean Finf of 0.53 ± 0.16 (p < 0.001). Within building types, private homes showed a significant seasonal difference in Finf with a mean of 0.76 ± 0.19 during the nonheating season, and 0.49 ± 0.11 during heating season (p < 0.001). The seasonal difference also was found for private apartments, with a mean of 0.82 ± 0.18 during nonheating season, and 0.56 ± 0.22 during heating season (p < 0.05). Group homes did not show a statistically significant seasonal difference, due in part to the small sample size (N = 6).

· We created a regression model to determine factors influencing Finf. In addition to season, the use of an air cleaner was significantly associated with a lower average Finf, while the fraction of days with at least one open window was associated with an increased Finf.

· The seasonal difference in Finf is explained by a higher frequency of window opening during the nonheating season (70.4 ± 37.5 percent versus 42.1 ± 38.5 percent), and a higher average Finf on open window days.

Estimating Contribution of Indoor- and Outdoor-Generated Particles to Personal Air

· Thirty-minute personal PM2.5 data were collected from 27 subjects using personal DataRAM (pDR). These data (N = 9,173) were right skewed, with a geometric mean (GM) ± geometric standard deviation (GSD) of 7.7 µg/m3 ± 2.2 (arithmetic mean = 11.0 ± 13.9 µg/m3).

· Personal pDR concentrations differed by microenvironment. Across all pDR subjects, the GM 30-minute pDR concentration indoors at home (7.2 µg/m3 ± 2.1) was lower, after controlling for season, than outdoors near home (14.8 µg/m3 ± 2.1), in transit (11.9 µg/m3 ± 2.2), at work (19.0 µg/m3 ± 1.9), outdoors away from home (13.9 µg/m3 ± 1.9), and indoors away from home (11.7 µg/m3 ± 2.3).

· The adult cohorts all received an average of at least 77 percent of their PM exposure indoors at home, while the asthmatic subjects received 34 percent of their exposure in other indoor environments (primarily school).

· The overall mean alpha across all subjects with available Finf estimates (N = 55) was 0.68 ± 0.21 (range = 0.15-1.00).

· Our modeled a estimates agree well with the sulfur tracer technique (N = 12, regression slope = 1.48, R2 = 0.76).

· GM of estimated hourly exposures to outdoor- and indoor-generated particles of 4.5 µg/m3 ± 1.9 and 1.2 µg/m3 ± 2.3, respectively.

· The mean hourly Epact concentration across all subjects (N = 14) was 3.4 ± 10.9 µg/m3 (median = 0.9 µg/m3), with a range for individual subjects of 0.3 to 8.1 µg/m3 (median = 0.3 to 2.8 µg/m3).

Future Activities:

We will complete manuscripts on source apportionment and the indoor/outdoor contribution to personal exposures in a few months. In addition, we will conduct an extensive validation and sensitivity analysis of the recursive model results. This analysis will include the use of simulated data sets to assess the model's ability to estimate the true values of P, a, k, and Finf. We will test the influence on modeled estimates of the frequency and magnitude of indoor sources, as well as the light scattering-to-mass relationship during indoor particle-generating events. We also are interested in examining the ability of the recursive model to estimate particle infiltration on a time scale below 10 days.

For organics, Dr. Lara Gundel will complete gas/particle partitioning measurements for samples collected in Seattle, 2000-200l; analysis of integrated organic gas and particle sampler (IOGAPS) samples from agricultural burning; advance sampling and measurement techniques for semi-volatile organic compounds (SVOC) via application of porous foam; and retrospective analysis of optical signals for differential thermal analysis of Seattle PM collected 2000-2001.

Regarding the integrated plate (IP) results, we will analyze the rest of the personal panel study filters to obtain source apportionment results for all subjects (to be used in health effect assessments). The analysis period for the first batch spanned about 3 months, but it could have been much shorter if the baseline was stabilized. The stability of the instrument "baseline" varied by day, often exceeding quality control limits. This resulted in the protraction of the analysis period. Norm Ahlquist of Atmospheric Sciences assembled the IP unit. We will work with him to resolve the baseline problem. Analyses will continue, regardless of any maintenance, because quality control measures prevent the collection of inaccurate readings.

Journal Articles on this Report : 2 Displayed | Download in RIS Format

Other subproject views: All 65 publications 25 publications in selected types All 25 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 Liu L-JS, Slaughter JC, Larson TV. Comparison of light scattering devices and impactors for particulate measurements in indoor, outdoor, and personal environments. Environmental Science & Technology 2002;36(13):2977-2986. R827355 (2004)
R827355 (Final)
R827355C001 (Final)
R827355C003 (2001)
R827355C003 (2002)
R827355C003 (Final)
R827355C008 (Final)
  • Abstract from PubMed
  • Full-text: ResearchGate-Abstract and Full Text PDF
  • Abstract: ACS-Abstract
  • Other: ACS-Full Text HTML
  • Journal Article Pang Y, Gundel LA, Larson T, Finn D, Liu L-JS, Claiborn CS. Development and evaluation of a personal particulate organic and mass sampler. Environmental Science & Technology 2002;36(23):5205-5210. R827355 (2004)
    R827355 (Final)
    R827355C003 (2002)
    R827355C003 (Final)
  • Abstract from PubMed
  • Full-text: ResearchGate - Abstract & Full Text PDF
  • Abstract: ACS-Abstract
  • Other: ACS-Full Text PDF
  • Supplemental Keywords:

    air pollution, particulate matter, PM, air pollutants, health effects, exposure, personal exposure, indoor exposure, outdoor exposure, fine particulates, PM2.5, exposure assessment, susceptible populations, high-risk subpopulations, PM exposure, monitoring, ambient PM sources, microenvironments, microenvironmental model, chronic obstructive pulmonary disease, COPD, respiratory disease, pulmonary disease, cardiac disease, heart disease, source apportionment, particles, Seattle, Washington, WA, seasonal differences, model., RFA, Health, Scientific Discipline, Air, Geographic Area, particulate matter, air toxics, Environmental Chemistry, Health Risk Assessment, Epidemiology, State, Northwest, Risk Assessments, Susceptibility/Sensitive Population/Genetic Susceptibility, Biochemistry, genetic susceptability, indoor air, Atmospheric Sciences, ambient aerosol, ambient air quality, asthma, biostatistics, health effects, particulates, PM10, sensitive populations, air pollutants, cardiopulmonary responses, fine particles, health risks, human health effects, morbidity, PM 2.5, toxicology, stratospheric ozone, exposure and effects, ambient air, exposure, hazardous air pollutants, animal model, combustion emissions, air pollution, children, Human Health Risk Assessment, particle exposure, cardiopulmonary response, human exposure, inhalation, PAHs, atmospheric aerosols, ambient particle health effects, mortality studies, hydrocarbons, human susceptibility, Seattle, Washington, incineration, indoor air quality, mortality, California (CA), allergens, aerosols, air quality, atmospheric chemistry, cardiovascular disease, exposure assessment, human health risk

    Relevant Websites:

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

    Progress and Final Reports:

    Original Abstract
  • 1999 Progress Report
  • 2000 Progress Report
  • 2001 Progress Report
  • 2003 Progress Report
  • 2004 Progress Report
  • 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