A 63-year-old white man with a history of coronary artery disease, hypertension, and diabetes mellitus was referred to the pulmonary clinic for persistent dry cough and shortness of breath. In May 2000, he began to have dry cough, malaise, and occasional chills. Previously, he had been able to walk for a mile without significant shortness of breath, but by the end of the summer months he was unable to walk 10 feet without significant dyspnea. He reported no fever or purulent sputum. He also denied hemoptysis, rhinorrhea or sinus congestion, chest pain, orthopnea, paroxysmal nocturnal dyspnea, or peripheral edema. He did report an unintended weight loss of eight pounds over the course of the summer. On further questioning, he admitted to having had similar symptoms during the previous three summers that resolved after the first frost in the autumn. His review of systems was significant for the absence of visual abnormalities, dermatitis, arthralgia, myalgia, or recurrent infection. He has a remote history of tobacco use, approximately 10 pack-years. He is a farmer who grows herbs and vegetables but not roses or flowers. He lives in an 80-year-old log home and does not have any pets. He denied significant exposure to asbestos or silica, but has had annual exposure to pesticides and fertilizers.