Examining the social distributions in neighbourhood black carbon and ultrafine particles in Montreal and Toronto, Canada

Background: Socioeconomic inequities in outdoor ultrafine particles (UFP) and black carbon (BC) are understudied in Canada, where metropoles like Montreal and Toronto feature distinct sociodemographic diversity and urban characteristics compared to U.S. cities. Methods: We collected vulnerability in...

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Main Authors: Emmanuelle Batisse, Marshall Lloyd, Alicia Cavanaugh, Arman Ganji, Junshi Xu, Marianne Hatzopoulou, Jill Baumgartner, Scott Weichenthal
Format: Article
Language:English
Published: Elsevier 2025-04-01
Series:Environment International
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Online Access:http://www.sciencedirect.com/science/article/pii/S0160412025001461
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author Emmanuelle Batisse
Marshall Lloyd
Alicia Cavanaugh
Arman Ganji
Junshi Xu
Marianne Hatzopoulou
Jill Baumgartner
Scott Weichenthal
author_facet Emmanuelle Batisse
Marshall Lloyd
Alicia Cavanaugh
Arman Ganji
Junshi Xu
Marianne Hatzopoulou
Jill Baumgartner
Scott Weichenthal
author_sort Emmanuelle Batisse
collection DOAJ
description Background: Socioeconomic inequities in outdoor ultrafine particles (UFP) and black carbon (BC) are understudied in Canada, where metropoles like Montreal and Toronto feature distinct sociodemographic diversity and urban characteristics compared to U.S. cities. Methods: We collected vulnerability indicators, including social, economic, household composition, and immigration status, at the dissemination area level for Montreal and Toronto using data from the 2006 and 2021 Canadian Census of Population. Areas were classified as disadvantaged, intermediate, or advantaged following K-means clustering analysis. We aggregated and calculated population-weighted average concentrations of BC and UFP, and UFP size at the dissemination area and cluster levels using high-resolution exposure surfaces, derived from year-long mobile monitoring campaigns conducted in each city during 2020–2021. Final exposure surfaces were generated by integrating predictions from land-use regression models and deep convolutional neural network models. Findings: We observed high within-city variations in aggregated air pollutant levels, with higher outdoor BC and UFP concentrations and smaller UFP sizes in areas near local sources such as major roads, railways, airports, and densely populated regions. Advantaged areas experienced the lowest median UFP concentrations in both Montreal (10,707 pt/cm3) and Toronto (10,988 pt/cm3), as well as the lowest BC concentrations (650 ng/m3) in Montreal. The highest median UFP concentrations were observed in intermediate areas in Montreal (15,709 pt/cm3) and disadvantaged areas in Toronto (12,228 pt/cm3). Conversely, the highest BC concentrations were observed in disadvantaged and intermediate areas in Montreal (805–811 ng/m3), and disadvantaged and advantaged areas in Toronto (1,228–1,252 ng/m3). Notably, high priority areas for the double burden of vulnerability and high BC and UFP concentrations were located near air pollutants local emission sources. Interpretation: Our findings highlight the importance of prioritizing exposure mitigation for populations residing near local sources and to understand contextual factors influencing inequities across cities and pollutants.
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spelling doaj-art-e8d52c68903740cc92c1771c684a3bac2025-08-20T02:24:58ZengElsevierEnvironment International0160-41202025-04-0119810939510.1016/j.envint.2025.109395Examining the social distributions in neighbourhood black carbon and ultrafine particles in Montreal and Toronto, CanadaEmmanuelle Batisse0Marshall Lloyd1Alicia Cavanaugh2Arman Ganji3Junshi Xu4Marianne Hatzopoulou5Jill Baumgartner6Scott Weichenthal7Department of Epidemiology, Biostatistics and Occupational Health, McGill University, 2001 McGill College Ave, Montreal, Quebec H3A 1G1, CanadaDepartment of Epidemiology, Biostatistics and Occupational Health, McGill University, 2001 McGill College Ave, Montreal, Quebec H3A 1G1, CanadaScientific Consulting Group, 656 Quince Orchard Road, Suite 210, Gaithersburg, MD 20878, United StatesDepartment of Civil & Mineral Engineering, University of Toronto, 35 St. George St., Toronto, Ontario M5S 1A4, CanadaDepartment of Civil & Mineral Engineering, University of Toronto, 35 St. George St., Toronto, Ontario M5S 1A4, CanadaDepartment of Civil & Mineral Engineering, University of Toronto, 35 St. George St., Toronto, Ontario M5S 1A4, CanadaDepartment of Epidemiology, Biostatistics and Occupational Health, McGill University, 2001 McGill College Ave, Montreal, Quebec H3A 1G1, Canada; Corresponding author at: Departments of Equity, Ethics and Policy & Epidemiology, Biostatistics and Occupational Health, McGill University, 2001 McGill College Avenue, Room 1200, Montreal, Quebec H3A1G1, Canada.Department of Epidemiology, Biostatistics and Occupational Health, McGill University, 2001 McGill College Ave, Montreal, Quebec H3A 1G1, Canada; Corresponding author at: Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, 2001 McGill College Avenue, Room 1277, Montreal, Quebec H3A 1G1, Canada.Background: Socioeconomic inequities in outdoor ultrafine particles (UFP) and black carbon (BC) are understudied in Canada, where metropoles like Montreal and Toronto feature distinct sociodemographic diversity and urban characteristics compared to U.S. cities. Methods: We collected vulnerability indicators, including social, economic, household composition, and immigration status, at the dissemination area level for Montreal and Toronto using data from the 2006 and 2021 Canadian Census of Population. Areas were classified as disadvantaged, intermediate, or advantaged following K-means clustering analysis. We aggregated and calculated population-weighted average concentrations of BC and UFP, and UFP size at the dissemination area and cluster levels using high-resolution exposure surfaces, derived from year-long mobile monitoring campaigns conducted in each city during 2020–2021. Final exposure surfaces were generated by integrating predictions from land-use regression models and deep convolutional neural network models. Findings: We observed high within-city variations in aggregated air pollutant levels, with higher outdoor BC and UFP concentrations and smaller UFP sizes in areas near local sources such as major roads, railways, airports, and densely populated regions. Advantaged areas experienced the lowest median UFP concentrations in both Montreal (10,707 pt/cm3) and Toronto (10,988 pt/cm3), as well as the lowest BC concentrations (650 ng/m3) in Montreal. The highest median UFP concentrations were observed in intermediate areas in Montreal (15,709 pt/cm3) and disadvantaged areas in Toronto (12,228 pt/cm3). Conversely, the highest BC concentrations were observed in disadvantaged and intermediate areas in Montreal (805–811 ng/m3), and disadvantaged and advantaged areas in Toronto (1,228–1,252 ng/m3). Notably, high priority areas for the double burden of vulnerability and high BC and UFP concentrations were located near air pollutants local emission sources. Interpretation: Our findings highlight the importance of prioritizing exposure mitigation for populations residing near local sources and to understand contextual factors influencing inequities across cities and pollutants.http://www.sciencedirect.com/science/article/pii/S0160412025001461Environmental justiceAir pollutionVulnerabilityUltrafine particlesBlack carbon
spellingShingle Emmanuelle Batisse
Marshall Lloyd
Alicia Cavanaugh
Arman Ganji
Junshi Xu
Marianne Hatzopoulou
Jill Baumgartner
Scott Weichenthal
Examining the social distributions in neighbourhood black carbon and ultrafine particles in Montreal and Toronto, Canada
Environment International
Environmental justice
Air pollution
Vulnerability
Ultrafine particles
Black carbon
title Examining the social distributions in neighbourhood black carbon and ultrafine particles in Montreal and Toronto, Canada
title_full Examining the social distributions in neighbourhood black carbon and ultrafine particles in Montreal and Toronto, Canada
title_fullStr Examining the social distributions in neighbourhood black carbon and ultrafine particles in Montreal and Toronto, Canada
title_full_unstemmed Examining the social distributions in neighbourhood black carbon and ultrafine particles in Montreal and Toronto, Canada
title_short Examining the social distributions in neighbourhood black carbon and ultrafine particles in Montreal and Toronto, Canada
title_sort examining the social distributions in neighbourhood black carbon and ultrafine particles in montreal and toronto canada
topic Environmental justice
Air pollution
Vulnerability
Ultrafine particles
Black carbon
url http://www.sciencedirect.com/science/article/pii/S0160412025001461
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