Childrenʼs Exposure to Ambient Air Pollution: The Application of Different Exposure Assessment Methodologies

Abstract

SS6-03 Abstract: The Border Air Quality Strategy (BAQS), an international agreement between Canada and the United States, has led to a prioritization of research in Windsor, Ontario. Much of the health and exposure assessment research has focused on the potential impact of exposure to ambient air pollution on the health of preadolescent children. In September 2004, Health Canada issued a cross-sectional survey to all children, aged 7 to 14, enrolled in Windsor schools (n = 20,159) to determine their respiratory health status. Other respiratory risk factor data collected in the survey included parental health, housing conditions, and self-reported measures of exposure to traffic. A response rate of 63.8% (n = 12,694) was obtained. Chronic exposure to a variety of air pollutants is being estimated for these participants using different methods. Ongoing air pollution measurements include intraurban monitoring at approximately 50 locations measuring particulate matter (fine and coarse mode), nitrogen dioxide, sulfur dioxide, polycyclic aromatic hydrocarbons, volatile organic compounds, and acid vapor. These pollutants are being monitored for a 2-week period in 4 different seasons between 2004 and 2007. Air pollution exposures are also being assessed using personal, indoor, and outdoor microenvironmental monitoring at 48 residences during cold and warm seasons throughout 2005 to 2007. This exposure study has a total of 1440 sample days (480 annually), which will be used to assess infiltration factors and activity patterns that influence personal exposure. Both of these air pollution monitoring studies are also colocated at both of the Environment Canada National Air Pollution Surveillance (NAPS) sites in Windsor, which are the typical central monitoring sites used when assigning exposure in health effects research. Chronic exposure will be estimated using historical data obtained from NAPS and compared with results obtained from the BAQS exposure assessment methods. Although the use of personal monitoring is the preferred method for characterizing an individual's exposure to air pollution, this method is not always viable in epidemiologic studies. The different methods of assessing exposure for the same population will allow a comprehensive investigation of the sources of exposure measurement error. This will be assessed by conducting an intermethod reliability analysis. Correlational analyses using the Pearson and Spearman rank correlation coefficients will identify any association between exposure metrics generated using these data sources and, moreover, explore whether agreement is differential by health status, age, and socioeconomic status. Findings from this intermethod reliability study will assist in the application of methods to adjust associations between air pollution and health outcome data for the effects of exposure measurement error.