[Possible mechanisms of nonspecific respiratory effects in certain types of occupational exposure]

A summary is made of the author's research related to non-specific respiratory effects of certain types of occupational exposure. Possible mechanisms of such effects are a) repeated mechanical lesions of the mucous membrane in the bronchial part of the respiratory tract, e.g. in prolonged exposure to dusts, b) disturbance in the process of clearance of the alveoli and respiratory pathways, resulting in increased tendency to infection, and chronic damage (manganese), and c) induced hyperreactivity of the bronchi with symptoms of bronchial asthma and faster reduction in ventilatory lung function in relation to the expected fall with regard to age. The possible significance of combined exposure to aerosols of solid particles of small aerodynamic diameter and gaseous irritants is emphasized. By adsorption on dust particles the gaseous irritants of the upper part of the respiratory tract are carried deep into areas not usually penetrated, where, because adsorption is a reversible bond, they are released and can cause a local irritative effect. When evaluating the registered damage the role of other environmental factors should be kept in mind, particularly the habit of smoking, because of the possible supplementary and occasionally synergistic effect.