Review Question - QID 212386

A 59-year-old man presents to his primary care physician with a 5-month history of breathing difficulties. He says that he has been experiencing exertional dyspnea that is accompanied by a nonproductive cough. His past medical history is significant for a solitary lung nodule that was removed surgically 10 years ago and found to be benign. He works as a secretary for a coal mining company, does not smoke, and drinks socially with friends. His family history is significant for autoimmune diseases. Physical exam reveals fine bibasilar inspiratory crackles in both lungs, and laboratory testing is negative for antinuclear antibody and rheumatoid factor. Which of the following is associated with the most likely cause of this patient's symptoms?