Alveoli become enlarged and damaged with reduced surface area in heavy smokers. The condition is called
Emphysema
In emphysema, over-inflation of the alveoli and rupture of alveolar walls occur. This decreases the surface area and pulmonary ventilation. Cigarette smoking is the major cause of emphysema. People with emphysema experience shortness of breath even with normal activities. Asthma is a respiratory condition marked by attacks of spasm in the bronchi of the lungs, causing difficulty in breathing. It is usually connected to allergic reactions or other forms of hypersensitivity.
Bronchitis causes inflammation of the mucous membrane in the bronchial tubes. Silicosis is a type of occupational lung disease caused due to prolonged exposure to particles of silica dust, as seen in workers in occupations such mining, glass manufacturing etc.