Comparison of measured and predicted ventilatory volumes in selected groups of industrial workers

A follow-up study of ventilatory volumes [forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1.0) and maximum expiratory flow at 50% of the FVC (MEF50)] was conducted for selected groups of workers from two plants involving the electrolytic extraction of aluminum (two groups with 95 and 38 workers, respectively), a cement industry (50 workers with chronic bronchitis and 96 healthy workers)and a shipyard (38 workers) during a period of 3 or 4 a. In the workers from the aluminum plant, particularly in those who were older and exposed longer to respiratory irritants, the fall in FVC was much higher than expected. Cement workers also showed a tendency towards more decreased FVC values than expected, and the fall in MEF50 was particularly pronounced. The cement workers with chronic bronchitis had a slightly higher annual fall in the ventilatory volumes than the healthy cement workers. The observed fall in the MEF50 of the shipyard workers without a specific occupational exposure to dusts or respiratory irritants was unexpectedly high. An analysis of the relative values of the ventilatory volumes within the groups indicated individual differences among the exposed workers in regard to a possible chronic effect of occupational exposure to respiratory irritants. A drop in the ventilatory volumes during the follow-up period was not found to be directly dependent on the initial volume values. In the evaluation of the results, selection factors and ambient exposure to irritants were taken into account.