Bronchial gland dimensions in coalminers: influence of smoking and dust exposure

Bronchi from 94 coalminers were examined for enlargement of the mucous glands. The measurements used were the mean and maximum ratios of gland thickness to wall thickness, the mean acinar diameter, and the ratio of the gland area to the area of the non-cartilaginous portion of the bronchial wall. The relationships between these measurements and the subjects' smoking habits and their past exposure to dust in the coal mines were analysed. Smoking was found to be significantly related to mean and maximum gland-to-wall ratios. In addition, coalmine dust exposure was found to be significantly related to maximum gland:wall ratio. No significant relationships were found between gland dimensions and pneumoconiosis or dust retained in the lung. These results lend support to the view that irritants encountered in an occupational environment may play an important part in the development of hypersecretion of mucus.