Occupational exposure to diesel engine exhaust and first-time acute myocardial infarction - a nationwide register-based cohort study 1976- 2018.

Aims: Exposure to air pollution including diesel engine exhaust (DEE) is associated with increased risk of acute myocardial infarction (AMI). Few studies have investigated the risk of AMI according to occupational exposure to DEE. The aim of this study was to evaluate the association between occupational exposure to DEE and the risk of first-time AMI.

Methods: The study was a register-based cohort study of the Danish working population and included 903,415 individuals aged 35-50 years in 1995. Exposure estimates of DEE were assigned by linking a quantitative DEE job exposure matrix with the individual job history (1976-2017). National registers provided data on AMI throughout the follow-up period (1996-2018). The incidence rate ratios (IRR) for AMI were computed using Poisson regression while adjusting for demographics, comorbidities, socio-economic factors, ambient air pollution and occupational exposure to noise, physically demanding work, and job strain.

Results: 35,511 cases of AMI occurred during the follow-up period of 19,357,326 person-years. IRRs for cumulative exposure to DEE in the fully adjusted model were 1.04 (95%CI: 1.00-1.08) for exposure levels between the 50th and 75thpercentiles and 1.08 (95%CI: 1.04-1.12) for exposure levels ≥75thpercentile. Recent exposure to DEE was associated with an increased IRR in the highest exposed quartile (IRR=1.15 (95%CI: 1.05-1.27)), but only when compared within exposed workers.

Conclusion: Increasing exposure to DEE was associated with increasing IRR for first-time AMI across different exposure measures. The results indicate that AMI should be included in risk assessment of DEE when establishing occupational exposure limits.