Airway disease in non-smoking asbestos workers.

Ninety-seven non-cigarette-smoking white male insulators from the midwestern United States had significantly reduced forced expiratory volume in 1 second (FEV1.0) (P less than .0017) and forced expiratory flow from 75 to 85% of expired volume (FEF75-85) (P less than .042) when compared to a reference population of Michigan male nonsmokers. There were parenchymal opacities with a profusion of 1/0 or greater in 7 and pleural changes in 13 of these 97 nonsmokers. Asbestos, in the absence of cigarette smoke effects and other diseases, appears to decrease airflow, probably by the distortion of small airways (less than 2mm) by peribronchiolar fibrosis. This stiffening of the lung parenchyma protects midflow (FEF25-75) as the fibrosis increases the lung's radial traction on airways larger than 2 mm. This observation contributes to the natural history of physiological impairment due to asbestos disease.