Variation of lung function during the workshift among cotton and jute workers.

Cotton and jute dust exposure is known to induce reversible airway obstruction. We compared 50 exposed workers to 99 non exposed workers for the prevalence of respiratory symptoms and ventilatory impairment, and for variations in pulmonary function after five working days and after inhalation of salbutamol. The prevalence of respiratory symptoms was not significantly different between the two groups. Pulmonary function was not different on Monday morning, however, significant differences were observed on Friday afternoon. The exposed workers had a lower flow rate at 75% of exhaled forced vital capacity than controls (P less than 0.01). Salbutamol induced greater bronchodilatation in the exposed group. Comparison with a control group is necessary to take into account the change in pulmonary function. Repeated tests, combined with pharmacological tests, are able to differentiate the lung function pattern of exposed and non exposed workers.