is an inflammatory obstruction of the lung's tiniest airways, the bronchioles. The bronchioles may become damaged and inflamed after inhalation of toxic fumes, as a result of respiratory infections, in association with connective tissue disorders, or after bone marrow or heart-lung transplants. This leads to extensive scarring that blocks the airways, leading to a dry cough, shortness of breath, fatigue and wheezing in the absence of a cold or asthma. While there is no way to reverse the disease, treatments are available to stabilize or slow the progression.
Another similarly named disease, bronchiolitis obliterans organizing pneumonia, is a completely different disease. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.