Socioeconomic position and air pollution exposure in Western Europe: A multi-city analysis

Abstract

Background: Inconsistent associations between socioeconomic position (SEP) and air pollution have been reported in Europe. We aimed to assess association between SEP and air pollution exposure at residential address across 20 European cities with homogenised SEP and air pollution indicators. Methods: Three SEP indicators, defined at individual- (education and occupation) and small area-level (unemployment rate) were assessed in three European multicenter cohorts (ECRHS, EGEA and SAPALDIA). NO2 exposure was estimated at participants’ residential addresses with land use regression models developed within the European Study of Cohorts for Air Pollution Effects (ESCAPE). Pooled and city-specific linear regressions were used to analyse associations between each SEP indicator and NO2. Heterogeneity across cities was assessed using a random-effects meta-analysis. Results: 8666 participants from 20 European cities were included. In a pooled analysis, participants with lower individual-SEP indicators tended to be less exposed to NO2. Conversely, participants living in neighbourhood with higher unemployment rate were more exposed. However, in both cases, city-specific results exhibited considerable heterogeneity across areas (I2>75%). In models with both individual- and area-SEP indicators, estimates were similar compared to the simple regression model, suggesting independent associations between individual-SEP and small area-level unemployment rate with NO2. Conclusions: At European level, associations between SEP and NO2 were heterogeneous and no geographical or urban pattern could be identified. Our results showed that individual- and area-SEP indicators capture different aspects of the SEP distribution regarding exposure to air pollution, stressing the importance of considering both in air pollution epidemiological studies.