Lung function and respiratory symptoms related to changes in smoking habits in asbestos-exposed subjects

The purpose of this study was to examine respiratory symptoms and lung function (forced vital capacity [FVC] and forced expiratory volume in 1 second [FEV1]) as related to changes in smoking habits in subjects previously exposed to asbestos. The study was linked to a smoke-ending program among asbestos-exposed males. Subjects were recruited from a population-based survey, and 231 smokers met for the baseline consultation. The baseline prevalences of cough, chronic cough, and dyspnea among smokers were 68.0%, 44.6%, and 42.4%, respectively. Both smoke-ending (n = 10) and tobacco reduction (n = 52) during the 2-year follow-up resulted in remission of cough and chronic cough, whereas dyspnea was unaffected. When the 2-year measurements of FVC and FEV1 were adjusted for the respective baseline measurements, FEV1 tended to improve in subjects who had quit during the study, relative to the continuing smokers. It was concluded that both smoke-ending and reduction of tobacco consumption resulted in reduction of cough and chronic cough, but not of dyspnea. The study further suggests a possible positive effect of smoking cessation on FEV1, but not merely by reduction of tobacco consumption.