<prompt> A 50-year-old man working in a coal mining factory for 16 years develops symptoms of progressively worsening breathlessness and cough with expectoration. A spirometry was performed and his values were: FEV1 - 1.4 Lmin, FVC 2.8Lmin . What could be the cause?SilicosisHypersensitivity pneumonitisCOPDIdiopathic pulmonary fibrosis  <response>: The FEV1FVC ratio of the patient is low which indicates obstructive airway disease. Coal workers pneumoconiosis is associated with effects of coal dust on alveolar macrophages leading to the development of chronic bronchitis and COPD. Spirometry Obstructive lung disease Restrictive lung disease FEV1 VC FEV1FVC RV FRC Low Low Low High High Low Low Normal High Low Low 