Background: Occupational exposures have been associated with an increased risk of COPD. However, few studies have related objectively assessed occupational exposures to prospectively assessed incidence of COPD, using postbronchodilator lung function tests. Our objective was to examine the effect of occupational exposures on COPD incidence in the European Community Respiratory Health Survey. Methods: General population samples aged 20–44 were randomly selected in 1991–1993 and followed up 20 years later (2010–2012). Spirometry was performed at baseline and at follow-up, with incident COPD defined using a lower limit of normal criterion for postbronchodilator FEV1/FVC. Only participants without COPD and without current asthma at baseline were included. Coded job histories during follow-up were linked to a Job-Exposure Matrix, generating occupational exposure estimates to 12 categories of agents. Their association with COPD incidence was examined in log-binomial models fitted in a Bayesian framework. Findings: 3343 participants fulfilled the inclusion criteria; 89 of them had COPD at follow-up (1.4 cases/1000 person-years). Participants exposed to biological dust had a higher incidence of COPD compared with those unexposed (relative risk (RR) 1.6, 95% CI 1.1 to 2.3), as did those exposed to gases and fumes (RR 1.5, 95% CI 1.0 to 2.2) and pesticides (RR 2.2, 95% CI 1.1 to 3.8). The combined population attributable fraction for these exposures was 21.0%. Interpretation: These results substantially strengthen the evidence base for occupational exposures as an important risk factor for COPD.

Support also provided by the National Institute for Health Researchthrough the Primary Care Research Network The coordination of the ECRHS III was fundedthrough the Medical Research Council (Grant Number 92091). ISGlobal is a member of the CERCA Programme /Generalitat de Catalunya. The present analyses are part of the Ageing Lungsin European Cohorts (ALEC) Study (www.alecstudy.org), which hasreceived funding from the European Union’s Horizon 2020 research andinnovation programme under grant agreement No. 633212.