Bronchitis is an inflammation of the airways, called bronchi, that carry air to the lungs. This condition can lead to the narrowing of the airways and excessive mucus (phlegm) production, causing symptoms such as a persistent cough and difficulty breathing. Bronchitis is divided into two main types: acute (short-term) and chronic (long-term), and can arise from different causes.

Causes of Acute Bronchitis:
The most common cause of acute bronchitis is typically viruses; respiratory viruses like those causing the common cold or flu are primary culprits. Less frequently, bacteria can also lead to acute bronchitis, especially in crowded or enclosed environments. Additionally, exposure to irritants (e.g., air pollution, chemicals), prolonged inhalation of very cold air, or allergic reactions in sensitive individuals can trigger acute bronchitis attacks.

Causes and Risk Factors for Chronic Bronchitis:
The primary cause of chronic bronchitis is cigarette smoke; both active and passive smoking contribute significantly to this condition. Other important risk factors besides smoking include prolonged exposure to air pollution, chemical fumes, dust, industrial smoke, and occupational irritants. Asthma and certain allergies can also increase the risk of bronchitis.