Physiological evidence that emphysema is not a feature of byssinosis

A group of women with byssinosis of grades 2 and 3 were seen consecutively over three years in an occupational outpatient clinic. Detailed lung function tests were performed and the results for smokers and non-smokers compared. One hundred and fifty three patients were seen and 50 of these were life time non-smokers, 35 smoked one to nine cigarettes a day, and 68 smoked 10 or more cigarettes a day. After correction for age the mean FEV1 was found to be significantly lower (p less than 0.01) in heavy smokers than in non-smokers. In a subgroup of 89 subjects who were able to perform the carbon monoxide gas transfer test significantly lower values were obtained for the carbon monoxide transfer factor (TLCO), (p less than 0.001), TLCO % predicted (p less than 0.001), and the transfer coefficient (KCO) (p less than 0.001) in the heavy smokers than in the non-smokers, despite the fact that the non-smokers had worked longer in the cotton mills (p less than 0.02). The mean TLCO was significantly lower than predicted in the heavy smokers (p less than 0.001) but not in the non-smokers. A significant negative correlation was found between the number of cigarettes smoked per day and the TLCO (p less than 0.01), TLCO % predicted (p less than 0.001), and KCO (p = 0.005), but not with the number of years spent in the carding area. These results provide evidence supporting recent pathological observations that emphysema is probably due to concomitant cigarette smoking and is not itself a feature of byssinosis.