2001 Progress Report: Exposure Characterization Error

EPA Grant Number: R827351C001
Subproject: this is subproject number 001 , established and managed by the Center Director under grant R827351
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: EPA NYU PM Center: Health Risks of PM Components
Center Director: N/A
Title: Exposure Characterization Error
Investigators: Ito, Kazuhiko
Institution: New York University School of Medicine
EPA Project Officer: Chung, Serena
Project Period: June 1, 1999 through May 31, 2005 (Extended to May 31, 2006)
Project Period Covered by this Report: June 1, 2001 through May 31, 2002
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) quantitatively characterize spatio-temporal error of particulate matter (PM) components and gaseous co-pollutants measured at routine regulatory-based air monitors as a function of site characteristics using the entire U.S. air monitoring network; (2) to establish the relationship between the estimated error at a given monitoring site and the effect size/significance in mortality and morbidity models; and (3) evaluate the relative contribution of the error due to site-to-site and person-to-site variability. This project tests the prevailing hypothesis that the PM and gaseous co-pollutants data from a single air monitoring station can adequately reflect the population exposure for the entire city, and that resulting risk estimates and their significance are not biased.

Progress Summary:

In the past year, we have completed the analysis of nationwide PM10 and gaseous criteria pollutants. A manuscript has been written on the results and is being submitted. Spatial uniformity of temporal correlation was examined by computing monitor-to-monitor correlation using available multiple monitors for PM10 and gaseous pollutants (NO2, SO2, CO, and O3) in the nationwide data between 1988-1997. For each monitor, the median of temporal correlation with other monitors within the Air Quality Control Region (AQCR) was computed. The resulting median correlation was modeled as a function of qualitative site characteristics (i.e., land-use, location-setting, and monitoring-objective) and quantitative information (median separation distance, longitude/latitude or regional indicators) for each pollutant. Generalized Additive Models (GAM) with stringent convergence criteria were used to fit the smooth function of the separation distance and regional variation.

The intercepts of the models across pollutants showed the overall rank in monitor-to-monitor correlation on the average: O3, NO2, PM10, (0.7~0.8) > CO (~0.6) > SO2 (~0.4) (see Figure 1). Both the separation distance and the regional variation were important predictors of the correlation. For PM10, for example, the correlation for the monitors along the East Coast was higher by ~0.1 than the nationwide average. The qualitative monitor characteristics were often significant predictors of the variation in correlation, but their impacts were not substantial in magnitude for most categories (see Figure 2).

Figure 1. Monitor-to-monitor temporal correlation vs. separation distance for all the pairs of monitors analyzed.

Figure 2. Influence of land use categories on monitor-to-monitor correlations for PM10.

These results suggest that the apparent regional heterogeneity in PM effect estimates, as well as the differences in the significance of health outcome associations across pollutants, may in part be explained by the differences in monitor-to-monitor correlations by region and across pollutants.

In addition, we have completed the integration of weather and mortality data for the same period as the air pollution data analyzed above, and have started analyzing the associations between air pollution and mortality in large cities.

Future Activities:

We will continue to analyze the associations between PM10/gaseous pollutants and mortality in the nationwide data. The relationship between each monitor's median correlation with others and the corresponding mortality risk estimates will be examined. Finally, we will compare the magnitude of the error associated with monitor-to-monitor variability and that associated with person-to-monitor differences.

Journal Articles:

No journal articles submitted with this report: View all 7 publications for this subproject

Supplemental Keywords:

particulate matter, PM, exposure, clinical, toxicology, spatio-temporal, error, air monitor, mortality., RFA, Health, Scientific Discipline, PHYSICAL ASPECTS, Air, ENVIRONMENTAL MANAGEMENT, particulate matter, Environmental Chemistry, Health Risk Assessment, Risk Assessments, Environmental Monitoring, Physical Processes, Atmospheric Sciences, Atmosphere, Risk Assessment, ambient air quality, atmospheric particulate matter, particulates, air toxics, atmospheric particles, chemical characteristics, toxicology, ambient air monitoring, airborne particulate matter, ozone, environmental risks, exposure, Sulfur dioxide, air pollution, aerosol composition, atmospheric aerosol particles, human exposure, ozone monitoring, PM, exposure assessment

Progress and Final Reports:

Original Abstract
  • 1999 Progress Report
  • 2000 Progress Report
  • 2002 Progress Report
  • 2003 Progress Report
  • 2004
  • Final Report

  • Main Center Abstract and Reports:

    R827351    EPA NYU PM Center: Health Risks of PM Components

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R827351C001 Exposure Characterization Error
    R827351C002 X-ray CT-based Assessment of Variations in Human Airway Geometry: Implications for Evaluation of Particle Deposition and Dose to Different Populations
    R827351C003 Asthma Susceptibility to PM2.5
    R827351C004 Health Effects of Ambient Air PM in Controlled Human Exposures
    R827351C005 Physicochemical Parameters of Combustion Generated Atmospheres as Determinants of PM Toxicity
    R827351C006 Effects of Particle-Associated Irritants on the Cardiovascular System
    R827351C007 Role of PM-Associated Transition Metals in Exacerbating Infectious Pneumoniae in Exposed Rats
    R827351C008 Immunomodulation by PM: Role of Metal Composition and Pulmonary Phagocyte Iron Status
    R827351C009 Health Risks of Particulate Matter Components: Center Service Core
    R827351C010 Lung Hypoxia as Potential Mechanisms for PM-Induced Health Effects
    R827351C011 Urban PM2.5 Surface Chemistry and Interactions with Bronchoalveolar Lavage Fluid (BALF)
    R827351C012 Subchronic PM2.5 Exposure Study at the NYU PM Center
    R827351C013 Long Term Health Effects of Concentrated Ambient PM2.5
    R827351C014 PM Components and NYC Respiratory and Cardiovascular Morbidity
    R827351C015 Development of a Real-Time Monitoring System for Acidity and Soluble Components in Airborne Particulate Matter
    R827351C016 Automated Real-Time Ambient Fine PM Monitoring System