Smoking and the Lungs

Smoked tobacco delivers more than 3,000 chemicals including cyanide and other toxins directly to the lungs. Regular cigarettes contain 15 milligrams of tar each, while low-tar cigarettes contain 7 milligrams.

As a result, smoking can cause many lung diseases, including cancer, chronic bronchitis, emphysema, pulmonary vascular disease and lung immune system dysfunction.  

Cancer

Smokers have a significantly increased risk of developing cancer of the respiratory system, lips, mouth, pharynx, larynx, trachea, bronchi and lungs.

• Smoking is directly responsible for 90 percent of lung cancer deaths.

• Exposure to tobacco smoke is responsible for 30 percent of nonsmoker lung cancer deaths.

• Smokers have a 10- to 15-fold increase in lung cancer incidence.

• Once smoking is stopped, cancer risk is decreased.

• Cancer risk returns to normal after a person has quit smoking for 10 to 15 years.

• Patients often are diagnosed with cancer after they quit smoking.

• People with small cell cancer are more likely to develop secondary tumors if they do not quit smoking.

Chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is the presence of airflow obstruction due to chronic bronchitis (having a chronic productive cough for three months in each of two successive years when other causes of chronic cough have been excluded) or emphysema (abnormal permanent enlargement of small air spaces making breathing and exhaling difficult).

COPD typically is diagnosed in smokers who smoke an average of 20 cigarettes a day for 20 years. It usually occurs when a person is in his 50s and has a productive cough or acute respiratory illness. Shortness in breath and difficulty breathing usually does not develop until a person is in her 60s or 70s.

By Drew Edwards, MS; Mark S. Gold, MD
© 1999 University of Florida McKnight Brain Institute