Effects of long-term exposure to air pollution on natural-cause mortality: an analysis of 22 European cohorts within the multicentre ESCAPE project

Abstract

Few studies on long-term exposure to air pollution and mortality have been reported from Europe. Within the multicentre European Study of Cohorts for Air Pollution Effects (ESCAPE), we aimed to investigate the association between natural-cause mortality and long-term exposure to several air pollutants. We used data from 22 European cohort studies, which created a total study population of 367,251 participants. All cohorts were general population samples, although some were restricted to one sex only. With a strictly standardised protocol, we assessed residential exposure to air pollutants as annual average concentrations of particulate matter (PM) with diameters of less than 2.5 μm (PM2.5), less than 10 μm (PM10), and between 10 μm and 2.5 μm (PMcoarse), PM2.5 absorbance, and annual average concentrations of nitrogen oxides (NO2 and NOx), with land use regression models. We also investigated two traffic intensity variables-traffic intensity on the nearest road (vehicles per day) and total traffic load on all major roads within a 100 m buffer. We did cohort-specific statistical analyses using confounder models with increasing adjustment for confounder variables, and Cox proportional hazards models with a common protocol. We obtained pooled effect estimates through a random-effects meta-analysis. The total study population consisted of 367,251 participants who contributed 5,118,039 person-years at risk (average follow-up 13.9 years), of whom 29,076 died from a natural cause during follow-up. A significantly increased hazard ratio (HR) for PM2.5 of 1.07 (95% CI 1.02-1.13) per 5 μg/m(3) was recorded. No heterogeneity was noted between individual cohort effect estimates (I(2) p value=0.95). HRs for PM2.5 remained significantly raised even when we included only participants exposed to pollutant concentrations lower than the European annual mean limit value of 25 μg/m(3) (HR 1.06, 95% CI 1.00-1.12) or below 20 μg/m(3) (1.07, 1.01-1.13). Long-term exposure to fine particulate air pollution was associated with natural-cause mortality, even within concentration ranges well below the present European annual mean limit value. European Community's Seventh Framework Program (FP7/2007-2011).

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Affiliated Institutions

• Center for Research in Environmental Epidemiology ES
• Universität Ulm DE
• Leibniz Institute of Environmental Medicine DE
• Umeå University SE
• Agenzia Regionale Prevenzione e Ambiente della Regione Emilia-Romagna IT
• Université Paris-Sud FR
• Centre de recherche en Epidémiologie et Santé des Populations FR
• Fondazione IRCCS Istituto Nazionale dei Tumori IT
• Aarhus University DK
• Hellenic Health Foundation GR
• University College London GB
• Helmholtz Zentrum München DE
• Basque Government ES
• Danish Cancer Society DK
• Barcelona Biomedical Research Park ES
• University of Oxford GB
• National Centre for Disease Prevention and Control IT
• University of Turin IT
• University of Oslo
• University of Copenhagen DK
• Zimmer Biomet (Germany) DE
• Karolinska Institutet SE
• Heinrich Heine University Düsseldorf DE
• Utrecht University NL
• Inserm FR
• Centro de Investigación Biomédica en Red de Epidemiología y Salud Pública ES
• Institut Gustave Roussy FR
• Italian institute for Genomic Medicine IT
• Finnish Institute for Health and Welfare FI
• Imperial College London GB
• Institut de Veille Sanitaire FR
• University Medical Center Utrecht NL
• Norwegian Institute of Public Health
• Swiss Tropical and Public Health Institute CH
• University of Basel CH
• University of Washington US
• National Institute for Public Health and the Environment NL
• National and Kapodistrian University of Athens GR

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