1. Smoking:

Smokers have 10-13 times higher death rate compared to nonsmokers, and secondhand smoke is just as easy in inducing lung cancer.

2. Air pollution:

There is indoor and outdoor air pollution; in urban area, outdoor air pollution includes industrial air pollution, auto exhaust, road asphalt, and sulfur dioxide and nitrous oxide; indoor air pollution on the other hand contains harmful substances like coal tar fumes, coal smoke, and aromatic matters from inside of the buildings.

3. Occupational hazards:

Major carcinogens include asbestos, arsenic, chromium, nickel, coal tar, coal smoke, mustard gas, and chloromethyl ether. Artificial fibers, glass fibers, silicon dioxide, chloroethylene, petroleum, and ionizing radiation also have carcinogenic effect.

4. Hereditary factors:

Lung cancer is believed to appear within the same family line because it is highly heritable. Its patients often carry abnormal chromosome and therefore to some extent, it is potentially inheritable within fleshing blood.

5. Nutrition:

Long-term vitamin A, vitamin B, carotene, and micronutrients such as zinc and selenium deficiency often incur lung cancer.

6. Other factors:

Lung cancer also has something to do with the following disorders: tuberculosis, chronic bronchitis, interstitial pulmonary fibrosis, weakened immune function, and endocrine imbalances.

Smoking may cause cancer, lung disease, heart disease, or blindness, as well as male sexual dysfunction. Pregnant women may have miscarriage and give birth to premature baby.