Bronchitis
Cause

Most cases of chronic bronchitis are caused by tobacco smoking. Chronic bronchitis in young adults who smoke is associated with a greater chance of developing COPD. There is an association between smoking cannabis and chronic bronchitis. In addition, chronic inhalation of air pollution, or irritating fumes or dust from hazardous exposures in occupations such as coal mining, grain handling, textile manufacturing, livestock farming, and metal moulding may also be a risk factor for the development of chronic bronchitis. Bronchitis caused in this way is often referred to as industrial bronchitis, or occupational bronchitis. Rarely genetic factors also play a role.

Air quality can also affect the respiratory system with higher levels of nitrogen dioxide and sulfur dioxide contributing to bronchial symptoms. Sulfur dioxide can cause inflammation which can aggravate chronic bronchitis and make infections more likely.

Air pollution in the workplace is the cause of several non-communicable diseases (NCDs) including chronic bronchitis.
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