<unk>  bronchitis as a main category of COPD is caused by multiple environmental and genetic factors. Smoking is the leading cause of<unk>  bronchitis.
Chronic bronchitis causes
Acute bronchitis causes
Pneumoconiosis causes
Bronchiectasis causes
Bronchiolitis causes
Occupational lung disease causes
Alpha 1-antitrypsin deficiency causes
Alpha 1-antitrypsin deficiency risk factors