is the condition induced by the lungs becoming allergic (see ALLERGY) to various factors or substances. It includes BAGASSOSIS, FARMER'S LUNG and BUDGERIGAR-FANCIER'S LUNG, and is characterised by the onset of shortness of breath, tightness of the chest, cough and fever. The onset may be sudden or gradual. Treatment consists of removal of the affected individual from the offending material to which he or she has become allergic. CORTICOSTEROIDS give temporary relief.

In this disease there is diffuse FIBROSIS of the walls of the alveoli of the lungs. This causes loss of lung volume with resulting severe effects on breathing. The patient complains of cough and progressive DYSPNOEA. and may be cyanosed (blue – see CYANOSIS), clubbed (see CLUBBING), and have crackles in the mid- and lower-lung fields. BLOOD GASES will reveal HYPOXIA and, in early disease, hypocapnia (deficiency of carbon dioxide in the blood due to hyperventilation). There is an association with RHEUMATOID ARTHRITIS (about one-eighth of cases), systemic lupus erythematosus (see under LUPUS), and systemic SCLEROSIS. Certain drugs – for example, bleomycin, busulphan and hexamethonium – may also cause this condition, as may high concentrations of oxygen, and inhalation of CADMIUM fumes.