[Investigations of chronic bronchitis and bronchial obstruction in miners]

655 ore miners were investigated for detection of a chronic bronchitis, of difficulty in breathing and bronchial obstruction. Dependent on age and period of occupational life there was observed an increase in frequency of abnormal findings. Smoking cigarettes must be considered as a important cause of development of these diseases. On the other hand the importance of occupational influences recedes on conditions that the labour hygiene norms are observed.