Cigarette smoking causes damage to the lungs resulting in for example chronic bronchitis which is defined as an individual coughing with sputum production for at least 3 months per year, 2 years in a row. Bronchi are airway passages.
Another consequence of tobacco smoking is emphysema where there is irreversible abnormal dilatation of the air sacs with destruction of their walls. Sufferers develop shortness of breath for instance.
Chronic bronchitis and emphysema often occur simultaneously making up an entity known as chronic obstructive pulmonary disease (COPD).
Patients with COPD have a tendency of developing sudden worsening (exacerbations) of their disease triggered for example by infection with bacteria such as Moraxella catarrhalis. This bacterium is said to result in characteristic apple green sputum.
Sputum is material originating from the respiratory tract such as mucus, phlegm, pus, etc. that is either coughed up or swallowed.
Capewell S et al. Pneumonia due to Branhamella catarrhalis. Thorax, 1988 43(11):929-30. Go to reference
Cigarettes; emphysematous lung typical of smoking tobacco