Between February 1982 and October 1984, a total of 2,317 workers from all levels of cotton processing--carding, blowing, spinning and weaving--were studied in a citywide cross-sectional survey. The workers were administered the British MRC Questionnaire in local dialect and their pre- and postshift lung functions were assessed by portable spirometers. The prevalence of byssinosis for the whole industry was 2.3%, being much greater in the more dusty processes (blowing and carding, 5.6%; weaving 1.6%). Even more important was the prevalence of chronic obstructive airways disease (COAD) (13.8%) and a combination of nonspecific respiratory symptoms (10.0%), characterized by chest tightness and dyspnea, but not related to any specific day of the week such as those seen in typical byssinosis. The importance of these two large groups of respiratory problems in relation to byssinosis and the pathogenesis of respiratory diseases in people exposed to cotton dust is discussed.