This makes breathing very difficult and is caused by heavy smoking. It is a disease of the alveoli. If the alveoli have been broken, blown up, or blocked by tar, the surface area is reduced. This makes oxygen exchange more difficult. Emphysema makes people breathe faster and wheeze.
Carcinogens are in tobacco smoke and cause cancer of the lungs, mouth, gullet and bladder.
Nine out of ten people who die of lung cancer are heavy smokers. Bronchitis is mostly a smoker's disease. The passages to the lungs are swollen and sore because the smoke irritates them. Tiny hairs called cilia usually keep these passages clear but these cilia are stopped working by cigarette smoke and the lungs fill with mucus and tar. People try to remove the mucus by coughing.