Bronchitis is an inflammation of the airways leading into your lungs.

When your airways (trachea and bronchi) get irritated, they swell up and fill with mucus, causing you to cough. Your cough can last days to a couple of weeks. Bronchitis is an inflammation of the lining of your bronchial tubes, which carry air to and from your lungs. People who have bronchitis often cough up thickened mucus, which can be discolored. Bronchitis may be either acute or chronic.

Risk Factors: Chronic obstructive pulmonary disease

Symptoms: 

Cough. Production of mucus (sputum), which can be clear, white, yellowish-gray or green in color — rarely, it may be streaked with blood, Fatigue, Shortness of breath, Slight fever and chills.
Chest discomfort.