[A long-term prospective observation of the course of dust-induced bronchitis in mechanical engineering workers].

A study of 206 machine builders in dynamics (up to 15 years) with dust-induced bronchitis showed that the disease has a tendency to advancing within the first three years, especially in those with a combination of noxious professional factors (dust, heat, hard physical work). Negative risk factors: working conditions, preceding unspecific respiratory infections, smoking.