MRCP2-4154
A 70-year-old male presents to his GP complaining of shortness of breath for the past three weeks. He had a cold a few weeks ago and has been experiencing difficulty breathing ever since. Initially, he was coughing up green sputum, but now his cough is dry. He denies any chest pain or fever. He is retired but enjoys gardening and has an allotment where he grows vegetables and tubers. He used to work as an aerospace engineer, repairing and manufacturing electronic components. He is uncertain if he has ever been exposed to asbestos.
During the examination, the patient displays clubbing and appears emaciated. Bilateral apical crepitations are present, and he becomes breathless with activity. His oxygen saturation on air is 94%, and his respiratory rate is 28 breaths per minute.
What is the most probable diagnosis?