Mean Initial Values and Mean Changes of Ventilatory Volumes during the Follow - up Period in Total

Saric, M., Kalacic, I., and Holetic, A. (1976). British Journal ofIndustrial Medicine, 33, 18-24. Follow-up of ventilatory lung function in a group of cement workers. In a group of 160 active cement workers and 80 control workers selected on the basis of having or nothaving symptoms of chronic bronchitis, forcedvital capacity(FVC) and one second expiratory volume (FEVy.o), both corrected for age and height, and ratio of one second forced expiratory volume to forced vital capacity (FEV1.o/FVC(%)) were measured on two occasions with an interval of four and eight years respectively. The mean initial values of the forced expiratory indices and mean changes of these indices were computed in the total sample and in the following pairs of contrasted subgroups: chronic bronchitics-healthy workers: nonsmokers-smokers; youngerolder; exposed up to 10 years-exposed 10 or more years in cement plants; re-examined after four years-re-examined after eight years. In the group of cement workers as well as in the group of controls the values of ventilatory indices declined significantly during the follow-up period. Comparing the groups as a whole, using paired t test, only FEV1.o/FVC(%) values differed between cement and control workers with a statistically significant reduction in cement workers but not in controls. The analysis took into account the effects of smoking, symptoms of chronic bronchitis, age, duration of previous exposure to cement dust, and the interval between the two examinations. The rate of deterioration in ventilatory indices was fastest in the older workers with longest exposure. The decline in FVC does not seem to be affected by these factors. The results suggest that occupational exposure may contribute to the development of expiratory airflow obstruction.