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Bells Corners, Canada

Vanos J.K.,Environmental Health Research Bureau | Cakmak S.,Environmental Health Research Bureau | Kalkstein L.S.,University of Miami
WIT Transactions on Ecology and the Environment

The overall composition of the troposphere, including meteorological attributes and air pollution concentrations, affect human health outcomes. Our objectives were first to determine the likelihood of extreme air pollution events in select weather types within 12 Canadian cities, and second to examine the association between daily mortality and daily concentrations of air pollutants, assessing both single- and two-pollutant interactions. Each pollutant is examined to determine the likelihood of an extreme air pollution episode occurring in a given weather type and city. Next, we use a distributed lag nonlinear model (DLNM) to estimate city-specific relative risks of mortality (RR) due to the single and twoway- interactive effects of nitrogen dioxide (NO2), ozone (O3), sulphur dioxide (SO2), and particulate matter <2.5 μ (PM2.5) from 1981-2008.We control for exposure timeframe and time lag in days, as well as synoptic weather type, dayof- week, and mean air temperature. In dry tropical (DT) or moist tropical plus (MT+) weather, an extreme pollution event (top 5% of pollution levels) is found to be on average, four-fold and two-fold more likely to occur, respectively. We found significant RR effects of single-pollutant exposure on mortality for all four air pollutants examined. In the DM, MM, and MT weather types, moderate increases in average risk estimates for all pollutants are found, with increases of 4.5%, 4.1%, and 5.1%, respectively. However, for the DT or MT+ weather types, the overall average increases due to pollutant exposure are higher, at 14.9% and 11.9%, respectively. The two-way interactive effects have weaker effect estimates. Adjusting for O3 lowers the effect estimates and variability of theremaining pollutants, with 67% of the cases becoming significantly lower, and 40% of the cases becoming insignificant. Our findings suggest that the health effects of air pollution exposure differ under specific synoptic weather patterns. The forecasting of such weather can provide more accurate estimates of mortality risk due to air pollution for the overall population across Canada. © 2013 WIT Press. Source

Vanos J.K.,Environmental Health Research Bureau | Vanos J.K.,Texas Tech University | Cakmak S.,Environmental Health Research Bureau | Kalkstein L.S.,University of Miami | Yagouti A.,Climate Change and Health Office
Air Quality, Atmosphere and Health

It has been well established that both meteorological attributes and air pollution concentrations affect human health outcomes. We examined all cause nonaccident mortality relationships for 28 years (1981–2008) in relation to air pollution and synoptic weather type (encompassing air mass) data in 12 Canadian cities. This study first determines the likelihood of summertime extreme air pollution events within weather types using spatial synoptic classification. Second, it examines the modifying effect of weather types on the relative risk of mortality (RR) due to daily concentrations of air pollution (nitrogen dioxide, ozone, sulfur dioxide, and particulate matter <2.5 μm). We assess both single- and two-pollutant interactions to determine dependent and independent pollutant effects using the relatively new time series technique of distributed lag nonlinear modeling (DLNM). Results display dry tropical (DT) and moist tropical plus (MT+) weathers to result in a fourfold and twofold increased likelihood, respectively, of an extreme pollution event (top 5 % of pollution concentrations throughout the 28 years) occurring. We also demonstrate statistically significant effects of single-pollutant exposure on mortality (p < 0.05) to be dependent on summer weather type, where stronger results occur in dry moderate (fair weather) and DT or MT+ weather types. The overall average single-effect RR increases due to pollutant exposure within DT and MT+ weather types are 14.9 and 11.9 %, respectively. Adjusted exposures (two-way pollutant effect estimates) generally results in decreased RR estimates, indicating that the pollutants are not independent. Adjusting for ozone significantly lowers 67 % of the single-pollutant RR estimates and reduces model variability, which demonstrates that ozone significantly controls a portion of the mortality signal from the model. Our findings demonstrate the mortality risks of air pollution exposure to differ by weather type, with increased accuracy obtained when accounting for interactive effects through adjustment for dependent pollutants using a DLNM. © 2014, The Author(s). Source

Cakmak S.,Environmental Health Research Bureau | Hebbern C.,Environmental Health Research Bureau
WIT Transactions on Ecology and the Environment

Pollution levels and the effect of air pollution on human health can be modified by synoptic weather type and aeroallergens. We investigated the effect modification of aeroallergens on the association between CO, O3, NO2, SO2, PM10 and PM2.5 and asthma hospitalisation rates in seven synoptic weather types using single air pollutant models, adjusted for the effect of aeroallergens and stratified by synoptic weather type, with pooled relative risk estimates for asthma hospitalisation in ten Canadian cities. Aeroallergens significantly modified the relative risk in 19 pollutant-weather type combinations, reducing the size and variance for each single pollutant model. Aeroallergens did not significantly modify relative risk for any pollutant in the DT or MT weather types, or for PM10 in any weather type. There is an interactive effect between aeroallergens and CO, O3, NO2, SO2, and PM2.5, on asthma hospitalisations that differs under specific synoptic weather types. © 2014 WIT Press. Source

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