Pulmonary air space size in coal miners.

Abstract

Persistence of a monodisperse aerosol (mean diameter, 0.55 μm) in the human respiratory tract decreases exponentially with time of breath holding. The disappearance of aerosol from inspired gas with and without breath holding was expressed as half-life (t½) of aerosol persistence. The t½ of aerosol persistence can be used to estimate the average or effective diameter of the parenchymal air spaces. Aerosol half-life, lung volumes, maximal expiratory flow at 50 per cent of vital capacity, airway resistance, and single-breath CO diffusing capacity were measured in 35 underground coal miners with radiographic category 0 (no) pneumoconiosis, 34 with radiographic type q (micronodular) pneumoconiosis, and 58 with type p (pinhead) pneumoconiosis. There were no significant differences between the miners with type p and those with type q simple pneumoconiosis with regard to mean height, age, total lung capacity, forced vital capacity, ratio of forced expiratory volume in one sec to forced vital capacity, maximal ex...