Two hundred of those chemicals are poisonous and forty-three are known to cause cancer. It is a major factor in coronary heart disease and stroke. Smoking is also associated with mild airway obstruction, slower development of lung function, lower maximum lung function. This means a smoker's lungs provide less oxygen to the body, than a non-smokers. These negative effects occur more frequently in teens who smoke as few as five cigarettes a day.
Smokers tend to be sick more than non-smokers.
The tar in cigarettes paralyzes the fine hairs, or cilia, found in the nasal passages and bronchial tubes which carry air to the lungs. When the cilia become paralyzed it is easier for disease causing organisms to enter the body and cause upper respiratory infections. Even one cigarette can reduce the function of the cilia and heavy, long-term smoking destroys them. Switching to a menthol cigarette, or one that is lower tar and nicotine, does not reduce the health risks of smoking. People who smoke such cigarettes often inhale more deeply, hold the smoke in their lungs longer, smoke more cigarettes, and cover the air holes in the filters in order to get more nicotine.