Socioeconomic position and outdoor nitrogen dioxide (NO2) exposure in Western Europe: A multi-city analysis.
Inconsistent associations between socioeconomic position (SEP) and outdoor air pollution have been reported in Europe, but methodological differences prevent any direct between-study comparison.



Assess and compare the association between SEP and outdoor nitrogen dioxide (NO2) exposure as a marker of traffic exhaust, in 16 cities from eight Western European countries.



Three SEP indicators, two defined at individual-level (education and occupation) and one at neighborhood-level (unemployment rate) were assessed in three European multicenter cohorts. NO2annual concentration exposure was estimated at participants' addresses with land use regression models developed within the European Study of Cohorts for Air Pollution Effects (ESCAPE; http://www.escapeproject.eu/). Pooled and city-specific linear regressions were used to analyze associations between each SEP indicator and NO2. Heterogeneity across cities was assessed using the Higgins' I-squared test (I2).



The study population included 5692 participants. Pooled analysis showed that participants with lower individual-SEP were less exposed to NO2. Conversely, participants living in neighborhoods with higher unemployment rate were more exposed. City-specific results exhibited strong heterogeneity (I2>76% for the three SEP indicators) resulting in variation of the individual- and neighborhood-SEP patterns of NO2exposure across cities. The coefficients from a model that included both individual- and neighborhood-SEP indicators were similar to the unadjusted coefficients, suggesting independent associations.



Our study showed for the first time using homogenized measures of outcome and exposure across 16 cities the important heterogeneity regarding the association between SEP and NO2in Western Europe. Importantly, our results showed that individual- and neighborhood-SEP indicators capture different aspects of the association between SEP and exposure to air pollution, stressing the importance of considering both in air pollution health effects studies.
INSERM, U1168, VIMA: Aging and Chronic Diseases, Epidemiological and Public Health Approaches, F-94807 Villejuif, France; Univ Versailles St-Quentin-en-Yvelines, UMR-S 1168, F-78180 Montigny le Bretonneux, France; Univ Paris-Sud, Kremlin-Bicêtre, France. Electronic address: sofia.temam@inserm.fr.
Sofia
S
Temam
INSERM, U1168, VIMA: Aging and Chronic Diseases, Epidemiological and Public Health Approaches, F-94807 Villejuif, France; Univ Versailles St-Quentin-en-Yvelines, UMR-S 1168, F-78180 Montigny le Bretonneux, France.
Emilie
E
Burte
Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland.
Martin
M
Adam
ISGlobal-Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Hospital del Mar Medical Research Institute, Barcelona, Spain; Universitat Pompeu Fabra, Barcelona, Spain; CIBER Epidemiología y Salud Pública, Barcelona, Spain.
Josep M
JM
Antó
ISGlobal-Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Universitat Pompeu Fabra, Barcelona, Spain; CIBER Epidemiología y Salud Pública, Barcelona, Spain.
Xavier
X
Basagaña
INSERM, U1168, VIMA: Aging and Chronic Diseases, Epidemiological and Public Health Approaches, F-94807 Villejuif, France; Univ Versailles St-Quentin-en-Yvelines, UMR-S 1168, F-78180 Montigny le Bretonneux, France; Centre Hospitalo-Universitaire, Montpellier, France.
Jean
J
Bousquet
ISGlobal-Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Universitat Pompeu Fabra, Barcelona, Spain; CIBER Epidemiología y Salud Pública, Barcelona, Spain.
Anne-Elie
AE
Carsin
School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
Bruna
B
Galobardes
Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland.
Dirk
D
Keidel
Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland.
Nino
N
Künzli
INSERM, U1168, VIMA: Aging and Chronic Diseases, Epidemiological and Public Health Approaches, F-94807 Villejuif, France; Univ Versailles St-Quentin-en-Yvelines, UMR-S 1168, F-78180 Montigny le Bretonneux, France.
Nicole
N
Le Moual
INSERM, U1168, VIMA: Aging and Chronic Diseases, Epidemiological and Public Health Approaches, F-94807 Villejuif, France; Univ Versailles St-Quentin-en-Yvelines, UMR-S 1168, F-78180 Montigny le Bretonneux, France.
Margaux
M
Sanchez
ISGlobal-Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Universitat Pompeu Fabra, Barcelona, Spain; CIBER Epidemiología y Salud Pública, Barcelona, Spain.
Jordi
J
Sunyer
Department of Public Health and Pediatrics, University of Turin, Turin, Italy.
Roberto
R
Bono
Institute for Risk Assessment Sciences, University Utrecht, Utrecht, The Netherlands; Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands.
Bert
B
Brunekreef
Institute of Epidemiology, German Research Center for Environmental Health (GmbH), Helmholtz Zentrum München, Neuherberg, Germany; Institute and Outpatient Clinic for Occupational, Social and Environmental Medicine Ludwig Maximilians University, Munich, Germany.
Joachim
J
Heinrich
Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland; Population Health and Occupational disease, National Heart and Lung Institute, Imperial College London, London, United Kingdom.
Kees
K
de Hoogh
Population Health and Occupational disease, National Heart and Lung Institute, Imperial College London, London, United Kingdom; MRC-PHE Centre for Environment and Health, Imperial College London, London, United Kingdom.
Debbie
D
Jarvis
Unit of Epidemiology and Medical Statistics, Department of Diagnostics and Public Health, University of Verona, Verona, Italy.
Alessandro
A
Marcon
Public Health and Clinical Medicine, Umea University, University Hospital, Umea, Sweden.
Lars
L
Modig
INSERM, U1168, VIMA: Aging and Chronic Diseases, Epidemiological and Public Health Approaches, F-94807 Villejuif, France; Univ Versailles St-Quentin-en-Yvelines, UMR-S 1168, F-78180 Montigny le Bretonneux, France.
Rachel
R
Nadif
ISGlobal-Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Universitat Pompeu Fabra, Barcelona, Spain; CIBER Epidemiología y Salud Pública, Barcelona, Spain.
Mark
M
Nieuwenhuijsen
IAB, Environmental Epidemiology Applied to Reproduction and Respiratory Health, INSERM, Grenoble, France; IAB, Environmental Epidemiology Applied to Reproduction and Respiratory Health, Univ Grenoble-Alpes, Grenoble, France; IAB, Environmental Epidemiology Applied to Reproduction and Respiratory Health, CHU Grenoble, Grenoble, France; Pédiatrie, CHU Grenoble, Grenoble, France.
Isabelle
I
Pin
IAB, Environmental Epidemiology Applied to Reproduction and Respiratory Health, INSERM, Grenoble, France; IAB, Environmental Epidemiology Applied to Reproduction and Respiratory Health, Univ Grenoble-Alpes, Grenoble, France; IAB, Environmental Epidemiology Applied to Reproduction and Respiratory Health, CHU Grenoble, Grenoble, France.
Valérie
V
Siroux
InVS, French Institute for Public Health Surveillance, Saint-Maurice, France.
Morgane
M
Stempfelet
Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland.
Ming-Yi
MY
Tsai
Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland.
Nicole
N
Probst-Hensch
INSERM, U1168, VIMA: Aging and Chronic Diseases, Epidemiological and Public Health Approaches, F-94807 Villejuif, France; Univ Versailles St-Quentin-en-Yvelines, UMR-S 1168, F-78180 Montigny le Bretonneux, France; ISGlobal-Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; Universitat Pompeu Fabra, Barcelona, Spain; CIBER Epidemiología y Salud Pública, Barcelona, Spain.
Bénédicte
B
Jacquemin
D000328:Adult; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000032:analysis; D001988:Bronchiolitis / Q000453:epidemiology* / Q000209:etiology; D002947:Cities; D003430:Cross-Sectional Studies; D004781:Environmental Exposure / Q000009:adverse effects; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009585:Nitrogen Dioxide / Q000032:analysis*; D009790:Occupations; D012959:Socioeconomic Factors; D001335:Vehicle Emissions / Q000032:analysis*
D000393:Air Pollutants; D001335:Vehicle Emissions; D009585:Nitrogen Dioxide
Air pollution; Environmental inequality; Europe; Socioeconomic position