Windsor, Ontario Exposure Assessment Study: Design and Methods Validation of Personal, Indoor, and Outdoor Air Pollution Monitoring

Air Health Science Division, Health Canada, Ottawa, Ontario, Canada.
Journal of the Air & Waste Management Association (1995) (Impact Factor: 1.34). 03/2011; 61(3):324-38. DOI: 10.3155/1047-3289.61.2.142
Source: PubMed


The Windsor, Ontario Exposure Assessment Study evaluated the contribution of ambient air pollutants to personal and indoor exposures of adults and asthmatic children living in Windsor, Ontario, Canada. In addition, the role of personal, indoor, and outdoor air pollution exposures upon asthmatic children's respiratory health was assessed. Several active and passive sampling methods were applied, or adapted, for personal, indoor, and outdoor residential monitoring of nitrogen dioxide, volatile organic compounds, particulate matter (PM; PM-2.5 pm [PM2.5] and < or =10 microm [PM10] in aerodynamic diameter), elemental carbon, ultrafine particles, ozone, air exchange rates, allergens in settled dust, and particulate-associated metals. Participants completed five consecutive days of monitoring during the winter and summer of 2005 and 2006. During 2006, in addition to undertaking the air pollution measurements, asthmatic children completed respiratory health measurements (including peak flow meter tests and exhaled breath condensate) and tracked respiratory symptoms in a diary. Extensive quality assurance and quality control steps were implemented, including the collocation of instruments at the National Air Pollution Surveillance site operated by Environment Canada and at the Michigan Department of Environmental Quality site in Allen Park, Detroit, MI. During field sampling, duplicate and blank samples were also completed and these data are reported. In total, 50 adults and 51 asthmatic children were recruited to participate, resulting in 922 participant days of data. When comparing the methods used in the study with standard reference methods, field blanks were low and bias was acceptable, with most methods being within 20% of reference methods. Duplicates were typically within less than 10% of each other, indicating that study results can be used with confidence. This paper covers study design, recruitment, methodology, time activity diary, surveys, and quality assurance and control results for the different methods used.

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    • "These samplers can be used to determine time-weighted average concentrations that are useful for comparing to regulatory criteria and informing the public. In Canada, several types of passive samplers have been used to measure SO 2 , NO 2 and O 3 concentrations for studying indoor and ambient air quality (Alberta Health and Wellness, 2000; Kindzierski and Sembaluk, 2001; Kindzierski and Ranganathan, 2006; Wheeler et al., 2011; Gibson et al., 2013; Hsu, 2013) and forest and vegetation exposures (Krupa and Legge, 2000; Cox, 2003). There is potential non-specificity and non-linearity in the performance of a passive sampler (Krupa and Legge, 2000). "
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    ABSTRACT: A field performance evaluation of Maxxam passive samplers was carried out for ambient concentrations of sulfur dioxide (SO2), nitrogen dioxide (NO2) and ground-level ozone (O3). Monthly passive and hourly continuous air monitoring data from four regional air monitoring networks in Alberta, Canada were evaluated over a 5-year period (2006–2010). Monthly concentrations were relatively low, ranging from 0.1 to 3.9 ppb, 0.2 to 18.1 ppb and 10.1 to 56.1 ppb for SO2, NO2 and O3, respectively. From duplicate passive sampling, geometric mean precision values were 17.9%, 14.8% and 4.7% for SO2, NO2 and O3, respectively. Geometric mean of the relative error (as a measure of accuracy) was 30% (median = 33%, interquartile range, IQR 15–63%) for SO2 and 32% (median = 33%, IQR = 25–64%) for NO2. O3 measurements had a better measure of accuracy with a geometic mean relative error of 12% (median = 17%, IQR = 9–30%) and met the acceptable level recommended by United States National Institute of Safety and Health (NIOSH) and the European Union (EU) Directive (±25%). From reduced major axis (RMA) analysis, bias (systematic error) is apparent in the Maxxam passive samplers in the field resulting in overestimation of ambient SO2 and O3 concentrations and underestimation of NO2 concentrations relative to continuous analyzers. Seasonal influences were observed for accuracy of passive SO2 and O3 measurements. A poor association was found between passive versus continuous concentrations for SO2 and O3 during the winter and the summer, respectively.
    Full-text · Article · May 2015 · Atmospheric Environment
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    • "Recent studies have documented the potential for measurement error to bias risk estimates toward the null for pollutants with high spatial variability (Suh and Zanobetti, 2010; Van Roosbroeck et al., 2008) and previous analyzes of exposure measurement error in timeseries studies of mortality suggest that risk estimates based on fixed-site ambient air pollution data are smaller than those estimated from personal measures (Schwartz et al., 2007; Zeger et al., 2000). In this study we examined the potential impact of exposure measurement error for short-term (24-h) exposure to NO 2 on risk estimates derived from a case-crossover analysis using existing data from Windsor, Ontario (Lavigne et al., 2012; Wheeler et al., 2011). In general, extremely weak correlations and slopes were observed between personal and fixed-site NO 2 concentrations among children and adults in Windsor and previous studies also report weak correlations (Linaker et al., 2000; Sarnat et al., 2000; 2006; Van Roosbroeck et al., 2008). "
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    ABSTRACT: Background: We examined the impact of data source and exposure measurement error for ambient NO2 on risk estimates derived from a case-crossover study of emergency room visits for asthma in Windsor, Canada between 2002 and 2009. Methods: Paired personal and fixed-site NO2 data were available from an independent population (47 children and 48 adults) in Windsor between 2005 and 2006. We used linear regression to estimate the relationship and measurement error variance induced between fixed site and personal measurements of NO2, and through a series of simulations, evaluated the potential for a Bayesian model to adjust for this change in scale and measurement error. Finally, we re-analyzed data from the previous case-crossover study adjusting for the estimated change in slope and measurement error. Results: Correlations between paired NO2 measurements were weak (R(2)≤0.08) and slopes were far from unity (0.0029≤β≤0.30). Adjusting the previous case-crossover analysis suggested a much stronger association between personal NO2 (per 1ppb) (Odds Ratio (OR)=1.276, 95% Credible Interval (CrI): 1.034, 1.569) and emergency room visits for asthma among children relative to the fixed-site estimate (OR=1.024, 95% CrI 1.004-1.045). Conclusions: Our findings suggest that risk estimates based on fixed-site NO2 concentrations may differ substantially from estimates based on personal exposures if the change in scale and/or measurement error is large. In practice, one must always keep the scale being used in mind when interpreting risk estimates and not assume that coefficients for ambient concentrations reflect risks at the personal level.
    Full-text · Article · Feb 2015 · Environmental Research
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    • "The WOEAS and TCHEQ sampling protocols were similar as technicians vacuumed a 4 m2 section of floor for a period of 4 minutes or until at least one gram of dust was collected and used high volume devices. In WOEAS, settled dust was collected using the High Volume Surface Sampling System (HVS3) vacuum [26], while TCHEQ used the Shop-Vac vacuum (Model: QAM70, 7.0 Amps), another high volume device, equipped with Dust Sampling Socks (X-Cell 100, Midwest Filtration, Cincinnati, OH, USA). In CHILD, house dust samples were collected using a standardized consumer model vacuum cleaner (Sanitaire, model S3686) fitted with a dust collection device designed especially for the CHILD study with the goal of increasing the collection efficiency without having to vacuum the entire area. "
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    ABSTRACT: Background Exposure to traffic-related air pollution (TRAP) can adversely impact health but epidemiologic studies are limited in their abilities to assess long-term exposures and incorporate variability in indoor pollutant infiltration. Methods In order to examine settled house dust levels of hopanes, engine lubricating oil byproducts found in vehicle exhaust, as a novel TRAP exposure measure, dust samples were collected from 171 homes in five Canadian cities and analyzed by gas chromatography–mass spectrometry. To evaluate source contributions, the relative abundance of the highest concentration hopane monomer in house dust was compared to that in outdoor air. Geographic variables related to TRAP emissions and outdoor NO2 concentrations from city-specific TRAP land use regression (LUR) models were calculated at each georeferenced residence location and assessed as predictors of variability in dust hopanes. Results Hopanes relative abundance in house dust and ambient air were significantly correlated (Pearson’s r=0.48, p<0.05), suggesting that dust hopanes likely result from traffic emissions. The proportion of variance in dust hopanes concentrations explained by LUR NO2 was less than 10% in Vancouver, Winnipeg and Toronto while the correlations in Edmonton and Windsor explained 20 to 40% of the variance. Modeling with household factors such as air conditioning and shoe removal along with geographic predictors related to TRAP generally increased the proportion of explained variability (10-80%) in measured indoor hopanes dust levels. Conclusions Hopanes can consistently be detected in house dust and may be a useful tracer of TRAP exposure if determinants of their spatiotemporal variability are well-characterized, and when home-specific factors are considered.
    Full-text · Article · Jun 2013 · Environmental Health
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