Preliminary approach to the diagnosis of byssinosis.

The prevalence of byssinosis was studied in two cotton mills by a standardized questionnaire and pulmonary function measurements (forced expiratory volume in 1 second; FEV1). In mill A, the dust level was high (57-159 mg/m3). Among 90 participants, 80 were interviewed twice at an interval of 4 months, and disagreement on actual presence or absence of byssinosis was 7.5 percent. Twenty out of ninety workers had complaints of Monday symptoms and the prevalence was 22.2 percent. In mill B, the dust control (6.8 mg/m3) was relatively good. Among 173 participants from the carding room, two had complaints of Monday symptoms and the prevalence was 1.2 percent. A significant correlation was found between duration of employment and prevalence of byssinosis in mill A. FEV1 was measured in 9 byssinotics, 29 nonbyssinotics, and 30 controls before and after work on Mondays and Wednesdays. A significant decrease of 177 ml on average (7.8%) was found in byssinotics after work on Monday, whereas in nonbyssinotics, the decrease of FEV1 was nonsignificant. In controls, a slight increase in FEV1 after work was observed.