Air pollution and mortality across socioeconomic groups in the Netherlands

BACKGROUND: We investigated whether associations betweenlong-termair pollution and(cause-specific)mortality outcomes differ across socioeconomic position (SEP) groups in the Netherlands.

METHODS: This nationwide cohort study included 9.9 million adults aged ≥30 years, from 2014 to 2019 in the Netherlands. We linkedannual averageresidential exposure toparticulate matter (PM 2.5, PM 10), andnitrogen dioxide(NO 2)withhousehold- and neighbourhood-level socioeconomic indicators (financial welfare, education, employment history), as well as the national death register. Using Cox proportional hazards models, we estimated hazard ratios (HRs) and absolute rate differences to assess relative and absolute inequalities in air pollution-related mortality.

RESULTS: Higher air pollution exposure was associated with increased mortality across pollutants and mortality outcomes. For example, a 5 µg/m 3 increase in PM 2.5was associated with a HR of 1.07 (95% CI: 1.06-1.08) for all natural-cause mortality.Relative risk estimates showed no consistentsocioeconomic gradient and varieddepending onthe indicator used.Absolute rate differences, however, showeda more consistentpattern wheregroups with lowerhousehold-levelsocioeconomic positionexperiencedgreater absolute mortality burdensfrom air pollution, driven bytheirhigher baseline mortality rates.

CONCLUSION: While air pollution increases mortality across all socioeconomic groups, disadvantaged populations bear disproportionate absolute burdens. Absolute risk measures reveal steeper health disparities than relative risks, underscoring the importance of reporting both metrics to fully capture environmental health inequities.