A 42-year-old male welder with 15 years of occupational exposure presents to the occupational health clinic for routine screening. He reports occasional mild dyspnea on exertion and a dry cough for 6 months. He denies fever, weight loss, or hemoptysis. On examination, breath sounds are normal. Chest X-ray shows bilateral upper lobe nodular opacities with fibrosis and mild hilar lymphadenopathy without calcification. Spirometry shows FEV₁ 72% predicted, FVC 78% predicted, and FEV₁/FVC ratio 0.92. High-resolution CT chest confirms centrilobular nodules in the upper lobes. What is the most appropriate next step in management?