The acute effect of cotton dust on respiratory function was assessed. Respiratory questionnaires, preshift and postshift pulmonary function testing and air sampling were completed for 176 cotton textile workers and 33 controls. The results showed a dose-response relationship between vertical elutriator dust measurements and change in forced expiratory volume at 1 s (FEV1) over the work shift. Dust levels of 0.2 mg/m3or less were not associated with significant acute falls in FEV1.