Which of the following is a common cause of bronchitis in COPD patients?

• A. Bacterial infection only
• B. Air pollution
• C. Cigarette smoke or inhaling secondhand smoke
• D. Viral infection

Answer: (C)

Irritation from cigarette smoke is the primary driver of chronic bronchitis in COPD. Long-term tobacco exposure damages the bronchial lining, causing ongoing inflammation, goblet cell hyperplasia, and increased mucus production with impaired ciliary clearance. This combination produces the productive cough and mucus buildup that define chronic bronchitis and contribute to airflow limitation in COPD. Inhaled secondhand smoke has the same irritant effect and is a major risk as well. Viral or bacterial infections can trigger acute exacerbations, and air pollution can worsen symptoms, but they are not the most common cause of chronic bronchitis in COPD when compared to direct smoke exposure. Stopping smoking can slow progression and improve symptom control.