Respiratory function during the day in cotton workers: a study in byssinosis.

Some of the workers in the dustier parts of a cotton mill (cardand blow-rooms) develop byssinosis. They experience tightness of the chest and breathlessness on Mondays or on the first day at work after an absence; these symptoms come on gradually, reaching a peak during the afternoon or early evening. In the early stages (Grade I) the workers feel quite fit by the next day; in the more severely affected the symptoms persist on Tuesdays, and even throughout the week (Grade II). Finally, disability may become permanent and severe (Schilling, Hughes, Dingwall-Fordyce and Gilson, 1955). In this study it was also shown that the ventilatory capacity of the lungs was related to the degree of byssinosis and was lower than in normal controls; in those with byssinosis it was also lower on Monday than Thursday. The present work was done to study in more detail the short-term effect of mill dust on respiratory function, and to find which simple respiratory test was the most sensitive measure of this effect. We thought that measurement of the change in ventilatory capacity over one day might prove preferable to a comparison between Monday and Thursday by being less affected by variations in weather and other extraneous influences. In Part I detailed studies on 12 mill workers with clinical byssinosis revealed a consistent pattern of change of ventilatory function within a single day, and in Parts II and III evidence has been obtained that these effects are specific to mill dust.