Ten-year Trends in Ambient PM2.5 and PM2.5-bound Element Concentrations in an Industrialized Border City

In this study, linear regression was adopted to characterize trends in ambient fine particulate matter (PM2.5) and PM2.5bounded element concentrations using data collected at Windsor West monitoring station in Windsor, Ontario, Canada, during 2003-2012.Twenty-two PM2.5-buonded elements were reported, and 10 of them had concentrations below method detection limits over 70% of the time.Therefore, they were excluded from further analysis.The 12 retained elements are Al, Br, Ca, Fe, K, Mn, Ni, Pb, S, Si, Ti and Zn.These 12 elements combined contributed 13% of total PM2.5 concentration, with S being the largest contributor (8.4%), followed by Fe (1.4%).The annual mean PM2.5 concentrations ranged from 7.3 µg/m 3 in 2009 to 10.4 µg/m 3 in 2005, are lower than the Canadian Ambient Air Quality Standards of 10 µg/m 3 for PM2.5 except for in 2005.The ten-year mean was 8.8 µg/m 3 .Significant decreasing trends were found for PM2.5 (25%), Fe (19%), Mn (47%), S (44%), Si (72%), Ti (92%), and Zn (71%), while no statistically significant change was observed for Al, Br, Ca, K, Ni, and Pb.Our findings suggest that the emission control strategies implemented during the study period were effective in reducing concentrations of PM2.5 and six out of 12 PM2.5-boundedelements in Windsor.