Follow-up of airway reactivity in potroom workers in relation to exposure.

Two groups of workers were studied: a) 24 workers with respiratory complaints--7 of whom were light and 4 borderline hyper-reactors--who continued to work on the electrolytic reduction of aluminium for up to two years; b) 30 workers with increased bronchial reactivity who ceased to work in potrooms for 3.7 years on average (range 2-11 years) because of respiratory complaints. Subjective respiratory complaints were recorded and a non specific bronchial reactivity test was performed one or two times during the follow-up period. A sustained level of airway reactivity was recorded in both groups of workers regardless of exposure conditions. In workers with dyspnoea and airway obstruction, bronchial reactivity did not worsen in spite of continued exposure. On the other hand cessation of exposure was not followed by normalization of bronchial reactivity. The potential role of atopy, smoking habits and length of previous exposure was analyzed. It appears that increased bronchial reactivity, once induced, has a tendency to persist. An improvement in subjective complaints may be expected after cessation of exposure.