AIR-FLOW OBSTRUCTION IN NONSMOKING, ASBESTOS-EXPOSED AND MIXED DUST-EXPOSED WORKERS

Obstructive changes in small airways have been described in patients e xposed to asbestos and other mineral dusts. The physiologic significan ce of these small airways abnormalities and their relationship to dust burden and alveolitis remain unclear. We performed bronchoalveolar la vage (BAL) in 30 nonsmoking and 30 age-matched smoking subjects, all w ith mild asbestos and mixed dust exposure, to determine if parameters of lung dust burden correlated with spirometric evidence of airflow ob struction. Seventeen of 30 nonsmoking subjects and 24 of 30 smoking su bjects met spirometric criteria for airflow obstruction. There were si gnificantly more obstructed subjects in both dust exposed groups (P < 0.05) than in an age-matched nondust exposed group. There was, however , no significant difference in the number of obstructed subjects betwe en the smoking and nonsmoking groups. There was no correlation in eith er group between airflow obstruction and total or differential cell co unts, ferruginous bodies, total asbestos fibers, or the percent of fre e silica in the particulate fraction recovered by BAL. We conclude tha t evidence of small airways obstruction occurs commonly in occupationa lly dust exposed subjects and appears to be related to dust exposure p er se and not to alveolar inflammation or fiber retention, important f actors in the development of alveolitis and interstitial lung disease.