Bronchitis is often caused by viral infections, such as the common cold or influenza, but can also result from bacterial infections or exposure to irritants like smoke, dust, and pollution. Acute bronchitis typically develops following a respiratory infection, while chronic bronchitis is often linked to long-term exposure to irritants, particularly tobacco smoke. Maintaining good hygiene, avoiding smoking, and minimizing exposure to pollutants can help reduce the risk of developing bronchitis.