Clinically important FEV1 declines among coal miners: an exploration of previously unrecognised determinants

Objectives-The relation between occupational exposure to dust and loss of v entilatory lung function is now well established. However, many exposures d uring work and other activities might also have important roles in determin ing clinically important losses of lung function. In this study, we attempt ed to explore additional plausible determinants of exposures and other pote ntial risk factors for clinically important decline in forced expiratory vo lume in 1 second (FEV1) during work in dusty trades. Methods-The study was performed in 264 underground coal miners whose lung f unction had been followed up for an average of 11 years. With an extensive follow up questionnaire, miners were asked about their occupational and non occupational exposures, smoking, personal and family medical history, and L iving conditions during childhood. Results-Several variables of the mine environment (as well as previously re cognised effects of mining work and region) were found to be associated wit h excess decline in FEV1, including work in roof bolting, exposure to explo sive blasting, and to control dust spraying water that had been stored in h olding tanks. Use of respiratory protection seemed to reduce the risk of de cline in FEV1. Other factors that were found to be associated with declines in pulmonary function included smoking, body mass, weight gain, childhood pneumonia, and childhood exposure in the home to passive tobacco smoke and possibly smoke due to wood and coal fuels. Miners with excessive decline in FEV1 were less likely to be working in mining jobs at follow up. Conclusions-These findings suggest the existence of additional risk factors for decline in lung function in dusty trades, and may be useful in develop ing additional approaches to the prevention of chronic respiratory disease.