Background: Long-term exposure to air pollution has been associated with mortality in urban cohort studies. Few studies have investigated this association in large-scale population registries, including non-urban populations.

Objectives: The aim of the study was to evaluate the associations between long-term exposure to air pollution and nonaccidental and cause-specific mortality in the Netherlands based on existing national databases.

Methods: We used existing Dutch national databases on mortality, individual characteristics, residence history, neighborhood characteristics, and national air pollution maps based on land use regression (LUR) techniques for particulates with an aerodynamic diameter ≤ 10 μm (PM₁₀) and nitrogen dioxide (NO₂). Using these databases, we established a cohort of 7.1 million individuals ≥ 30 years of age. We followed the cohort for 7 years (2004–2011). We applied Cox proportional hazard models adjusting for potential individual and area-specific confounders.

Results: After adjustment for individual and area-specific confounders, for each 10-μg/m³ increase, PM₁₀ and NO₂ were associated with nonaccidental mortality [hazard ratio (HR) = 1.08; 95% CI: 1.07, 1.09 and HR = 1.03; 95% CI: 1.02, 1.03, respectively], respiratory mortality (HR = 1.13; 95% CI: 1.10, 1.17 and HR = 1.02; 95% CI: 1.01, 1.03, respectively), and lung cancer mortality (HR = 1.26; 95% CI: 1.21, 1.30 and HR = 1.10 95% CI: 1.09, 1.11, respectively). Furthermore, PM₁₀ was associated with circulatory disease mortality (HR = 1.06; 95% CI: 1.04, 1.08), but NO₂ was not (HR = 1.00; 95% CI: 0.99, 1.01). PM₁₀ associations were robust to adjustment for NO₂; NO₂ associations remained for nonaccidental mortality and lung cancer mortality after adjustment for PM₁₀.

Conclusions: Long-term exposure to PM₁₀ and NO₂ was associated with nonaccidental and cause-specific mortality in the Dutch population of ≥ 30 years of age.

Citation: Fischer PH, Marra M, Ameling CB, Hoek G, Beelen R, de Hoogh K, Breugelmans O, Kruize H, Janssen NA, Houthuijs D. 2015. Air pollution and mortality in seven million adults: the Dutch Environmental Longitudinal Study (DUELS). Environ Health Perspect 123:697–704; http://dx.doi.org/10.1289/ehp.1408254

Address correspondence to P.H. Fischer, Department for Environmental Health, Centre for Sustainability, Environment and Health, National Institute of Public Health and the Environment, Bilthoven, the Netherlands. Telephone: 31 30 2743315. E-mail: paul.fischer@rivm.nl

The research leading to these results was performed in close cooperation with Statistics Netherlands, which provided the national registry data and facilitated the statistical analyses. F. Janssen (Population Research Centre, Faculty of Spatial Sciences, University of Groningen) kindly provided the data on regional age-standardized smoking attributable mortality fractions; D. de Zwart (RIVM) kindly supported with editing the figures, and W. Swart (RIVM) with the analyses on geo-information systems.

The study was funded by the RIVM Strategic Research Program and The Ministry of Infrastructure and the Environment. The exposure assessment work to create exposure maps for 2001 was supported by grant RGI-137 from the Dutch program Ruimte voor Geoinformatie supported by the Ministry of Housing, Spatial Planning and the Environment. For the sensitivity analyses, we used data collected by Community Health Services (GGD) of GGD Fryslan, GGD Gooi & Vechtstreek, GGD Hollands Midden, GGD Rotterdam-Rijnmond, GGD Zuid-Holland West, GGD Hart voor Brabant, GGD West Brabant, GGD Brabant Zuidoost, GGD Limburg Noord, and GGD Zuid Limburg.

The authors declare they have no actual or potential competing financial interests.

Received: 10 February 2014 Accepted: 6 March 2015 Advance Publication: 11 March 2015 Final Publication: 1 July 2015

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