Working in swine-confinement buildings causes an accelerated decline in FEV1: a 7-yr follow-up of Danish farmers

Work in swine confinement units causes exposure to high levels of organic dust and is associated with a high prevalence of work-related respiratory symptoms and probably with accelerated decline in forced expiratory volume in one second (FEV1). A 7-yr follow-up on FEV1, forced vital capacity (FVC), bronchial reactivity, and respiratory symptoms was performed on 181 Danish farmers. The participation rate was 76.3% and nonparticipants had more symptoms, were more likely to be current-smokers and had lower lung function in the first survey than participants in both surveys. Farmers who worked exclusively with pigs in the follow-up had an accelerated decline in FEV1 but not in FVC compared with dairy farmers, where the observed decline in FEV1 was close to the expected. For a nonsmoking pig farmer compared to a nonsmoking dairy farmer the mean additional decline in FEV1 was 17 mL.yr(-1) (53.0 mL.yr(-1) versus 36.1 mL.yr(-1)). The authors conclude that working in swine confinement units causes an accelerated decline in forced expiratory volume in one second but not in forced vital capacity. The mean decline is similar to 0.5 L during a working life and some farmers will develop clinically significant airway obstruction due to work in swine confinement units.