Is mild byssinosis associated with small airways disease?

Attempts were made to determine if, in the mild stage of byssinosis, there are changes located to small airways and if bronchial reactivity is increased. Twenty-two cotton workers from two cotton mills outside Gothenburg were studied, 6 non-smokers without a history of byssinosis and 16 mild byssinotics, 10 of whom were smokers. They were examined before a Monday shift and then re-examined after another Monday shift, one or two weeks later. Spirometry, lung volumes, the single-breath nitrogen wash-out test and the maximum expiratory flows after air and helium-oxygen breathing were obtained. The bronchial reactivity to methacholine was also assessed before and after shift. We found no indication of deteriorated test values in the non-smoking group regardless of symptoms of byssinosis. However, the reactivity to methacholine was clearly increased compared to a control group. We conclude that changes of small airways are probably not characteristic for mild byssinosis and therefore probably not the predominant location of byssinotic lung changes.