The disease can be caused by breathing in irritant fumes, such as chlorine, ammonia, oxides of nitrogen or sulfur dioxide. Diacetyl, a chemical used to provide butter flavor in many foods, has also been suspected of causing bronchiolitis obliterans in workers who manufacture it or mix it into foods, such as butter-flavored popcorn. Bronchiolitis obliterans also can result from respiratory infections, a connective tissue disorder such as rheumatoid arthritis, and after a bone marrow, lung or heart-lung transplant.
Another similarly named disease, bronchiolitis obliterans organizing pneumonia, is a completely different disease.
