Change in the respiratory response to coarse cotton dust over a ten-year period.

Changes in respiratory function during a 10-year period were studied in a group of 34 men and 19 women exposed to coarse cotton dust. The prevalence of byssinosis increased significantly in the 10-year period both in men and women; in addition, there was an increase in the prevalence of all other chronic respiratory symptoms in 1973 compared to 1963. There was a significant decrease in forced expiratory volume in 1 sec and forced vital capacity over the Monday shift both in 1963 and 1973. In subjects who were without byssinosis in 1963 but who had developed it by 1973, there was a considerable decrease in forced expiratory volume in 1 sec in 1973. The mean annual decline of forced expiratory volume in 1 sec (70 ml) during the 10-year period in the men was much greater than expected on the basis of the prediction equation for normal males, and it was most pronounced in those with byssinosis at the time of both surveys (111 ml).