Risk of asthma and chronic obstructive pulmonary disease in a large historical cohort of Danish firefighters.

Abstract

Firefighters are exposed to numerous respiratory hazards, but large studies on the risk of pulmonary disease are scarce. The objective of this study was to examine incidence of asthma and chronic obstructive pulmonary disease (COPD) in a nationwide cohort of Danish firefighters. We used individual historical employment records on 11 968 Danish male firefighters primarily supplied by trade unions and fire agencies. Furthermore, we used the Supplementary Pension Fund Register to form an occupational reference group consisting of military employees. Information on respiratory incidence was retrieved from the nationwide Danish National Patient Registry. Age and calendar time standardised incidence ratio (SIR) and Poisson regression analyses (incidence rate ratio) were used for estimation of risks, including 95% CIs. Compared with military employees, the overall age and calendar-time adjusted risk for asthma was significantly increased among full-time firefighters (SIR=1.58, 95% CI 1.32 to 1.88), but not among part-time/volunteer firefighters. Full-time firefighters' risk for asthma did not vary by duration of employment. No consistent evidence of an increased risk for chronic obstructive pulmonary disease was detected. Danish firefighters have an increased risk of asthma, but the causes, whether occupational or not, remain to be established.