A consideration of risk factors and development of chronic bronchitis in a five-year follow-up study of an industrial population.

A five-year follow-up study in an industrial population showed that the prevalence and development of chest symptoms in men was related mainly to their smoking habits and, to a lesser degree, to age. Mean FEV1 values were related to age, and decrease in FEV1 was related to age and smoking habits. The levels of airborne dust and fluorides at the working places were related to the prevalence of chronic bronchitis (CB) symptoms, to the persistence of those symptoms during the five-year period, and to decrease of FEV1 values during that time. The decrease in FEV1 was especially noticeable among current smokers. The five-year incidence study showed that particular occupational factors do indeed have a real effect, but their meaning in the development of the CB syndrome is less marked than was expected from the prevalence rates.