Socioeconomic disparities in fine particulate matter exposure in Quebec, Canada

Abstract

BACKGROUND AND AIM: Racial-ethnic disparities in environmental exposures have been widely documented in the United States, but not in Canada. To investigate changes over 2001 to 2016 in disparities in exposure to ambient fine particulate matter (PM2.5) and its components, i.e. black carbon, mineral dust, ammonium, nitrate, organic matter, and sulfate by socioeconomic status in Quebec, Canada. METHODS: The gridded annual ambient PM2.5 and its components for 2001, 2006, 2011, 2016 estimated by satellite measurements of column aerosol optical depth and the GEOS-Chem chemical transport model were aggregated to census tracts in metropolitan areas and local centers for community services in the other regions. The population-weighted mean annual PM2.5 exposures were calculated for income, educational attainment, or immigration status subgroups for the four years. RESULTS:PM2.5 exposures increased slightly from 2001 to 2011 and then decreased to 2016 for all subgroups of income, education, and immigration status. Among the PM2.5 components, ammonium and sulfate concentrations decreased the most and organic matter increased slightly between 2001-2016. Immigrants were more exposed to PM2.5 than non-immigrants, and most educated populations were exposed to the highest PM2.5 levels. People from low-income families also lived in higher PM2.5 environments. Although from 2001 to 2016, the PM2.5 disparity between the most and the least educated, immigrant and non-immigrant, low-income and median-income subpopulations decreased from 0.85 to 0.63 µg/m3, 0.44 to 0.13 µg/m3, and 2.28 to 1.53 µg/m3 respectively, the PM2.5 remained higher for the most educated/low-income/immigrant groups in 2016 who tend to live in more polluted urban centers. Similar patterns of disparity were observed with PM2.5 components. CONCLUSIONS:Disparities in ambient particulate exposure have decreased in Quebec since 2001 but immigrants, low-income, and high-educated populations remain exposed to higher levels. Whether similar trends are seen for other pollutants like those from road traffic remains an open question. KEYWORDS: fine particulate matter, environmental disparity