A comparison of results from 1976 and 1986 respiratory health surveys of Lancashire textile workers involved in the spining or weaving of cotton fibers revealed significant declines in the prevalence of byssinosis and in the presence of airborne bacteria in the mill atmosphere. The 1986 respiratory health survey quiried 4,656 Lancashire textile workers who were employed in 31 mills; at the same time, tests measured the levels of airborne cotton dust and bacteria in work zones on the mill floor. Only 182 workers described symptoms characteristic fo byssinosis. The prevalence of byssinosis correlated with the number of years worked in the textile industry, ethnic origin, type of duty and dust exposure, quality of cotton, and smoking habits. The correlation between the presence of byssinosis and the concentration of total dust (less fiber fly) in work zones on the mill floor was highly significant (r = 0.92). Of the 182 workers with byssinosis, 22 exhibited Grade 1 symptoms, 90 exhibited Grade 1/2 symptoms, and 70 exhibited Grade 2 symptoms. 3 refs.