A 58 year old male chronic smoker 2 pack on monthly basis, smoking more than 12 years ago with hypertension and gastroesophageal reflux. His presenting symptoms are dyspnea for the past 6 months, dry cough for 2 and half years, and fatigue. He denies sputum, hemoptysis, or wheezing. In addition, he says that he has no fever, chills, chest pain, ankle swelling, or weight loss. Previous treatments taken antibiotics, bronchodilators, antacid Current medications: omeprazole 20 mg daily, lisinopril 20 mg daily Work history: He works as a assistant manager in a local bank. No chemical or welding exposures. Family history: He does not have any history of lung disease in his family. Physical examination: Breath sounds bilateral crackles at the bases. No rhonchi, no wheezing was heard. Cardiac and abdominal exams are normal. Very light clubbing of fingertips, normal coloration, no rashes and no joints swelling was seen. In office spirometry FEV1/FVC ratio 86%, FVC 53% and FEV1 58%. On 5 minutes walking patient experiences some dyspnoea. Chest X ray PA and lateral views show bilateral decreased lung volume with increased linear markings in peripheral lower lung areas. No vascular crowding. Cardiac stress test was found normal. Please make diagnosis and management.