Regional lung function in asbestos workers: observations and speculations

The clinical findings, occupational exposure, smoking history, pulmonary function, chest radiograph and ventilation-perfusion studies have been examined in 12 men exposed to asbestos fibers in the course of their work. Minor abnormalities of regional ventilation, consistent with early small airway dysfunction, were found in the fibrotic zones of most of the nonsmokers or mild cigarette smokers. The whole-lung washout times, estimated by visual inspection of serial washout images, were strongly correlated with measurements of airflow obstruction, but not with pack-years of smoking. There was a close correspondence between radiographic extent of pulmonary fibrosis and the abnormalities in pulmonary blood flow in these regions. The severity of the abnormalities in regional pulmonary blood flow was significantly correlated with the years of asbestos exposure (r = + 0.73, p less than 0.01). It is suggested that the magnitude of the disturbance in pulmonary blood flow in the fibrotic zones could be used to estimate the proportion of pulmonary dysfunction due to asbestos exposure.