Chronic bronchitis is a long-term inflammation of the bronchi, the large airways in the lungs, often resulting from prolonged irritation. It is one of the conditions under chronic obstructive pulmonary disease (COPD), a progressive lung disease that makes it harder to breathe. Chronic bronchitis is characterized by a persistent, productive cough (meaning it produces mucus) that lasts for at least three months in two consecutive years. Causes: Smoking is the most common cause of chronic bronchitis. Exposure to environmental irritants such as air pollution, dust, and chemical fumes. Long-term exposure to secondhand smoke. Symptoms: Persistent cough with mucus (sputum) production. Shortness of breath, especially during physical activity. Wheezing or whistling sound when breathing. Fatigue or feeling tired due to breathing difficulties. Diagnosis: Pulmonary function tests (like spirometry) to assess lung function. Chest X-ray or CT scan to look for lung damage. Blood tests to rul...