Environmental Exposures in a Cohort of Swedish Women – Are there Inequalities by Socioeconomic Status?

BACKGROUND/AIM: Recent reviews provide evidence for inequalities in environmental exposures between and within European populations. The aim of this study is to explore differences in exposure to air pollution, road-traffic noise, and greenness by multiple socio-economic determinants in a female cohort in Sweden. METHODS: 20,407 women born in 1914-48 residing in Uppsala County, Sweden, were followed from 1997 until migration, death, or end of follow-up in 2017. We combined survey data, time-varying register data, and spatial-temporal modelled air pollutants (PM₂.₅, PM₁₀, NO₂), road-traffic noise (Lden), and greenness (NDVI) at the residences. We descriptively assessed exposures over time and by categories of socio-economic variables, including age, civil status, employment status, education, individual, household, and area-based income, and municipality type. We applied linear regressions estimated with generalized estimating equations to assess differences in environmental exposures by socio-economic levels. RESULTS: At baseline (1997), the average age of 19,953 women with complete data was 61.9 years, 50% were still employed and 56% lived in urban areas. Compared with the baseline population, 67.8% (n=12,682) remained at the end of follow-up (2017). Over the 20-y follow-up, the average exposure to PM₂.₅, PM₁₀, and NO₂ declined significantly, however, levels of road-traffic noise and greenness were stable. Small but statistically significant differences in exposures were found across socio-economic levels. Suggested predictors of high exposure to air pollution, noise, and low greenness (only PM₁₀ changes compared to references and 95%-CI in μg/m³ shown) include high age (0.09 [0.05; 0.13]), being unmarried (0.09 [0.01; 0.17]), divorced/widowed (0.09 [0.05; 0.12]), or retired (0.03 [0.01; 0.05]), having high education (0.07 [0.004; 0.14]), high individual income (0.03 [0.003; 0.05]), but low area-based income (0.26 [0.20; 0.31]). CONCLUSION: This study provides evidence of a complex interplay between environmental exposure and levels of socio-economic determinants. KEYWORDS: Air pollution, road-traffic noise, greenness, socio-economy, inequality